Re: [PATCH net-next 1/1] net_sched: Introduce skbmod action

On 16-07-18 05:44 AM, Daniel Borkmann wrote:

On 07/18/2016 08:51 AM, Jamal Hadi Salim wrote:

quoted

On 16-07-18 12:19 AM, Alexei Starovoitov wrote:

Looking at that just out of curiosity on how complex it could look
for src/dst mac, is it actually functional in iproute2 upstream tree?

No it is a bunch of bash script wrapping we did on top of pedit (which
should be no different than adding it to m_pedit as an extension).
We started there then decided that this feature is mostly used with
mirred all the time - so modified  mirred.

All I see is that pedit can look up 3rd party modules via get_pedit_kind(),
so it will pick p_%s.so, if built as such, and there's code for p_ip,
p_tcp, p_udp, p_icmp. But then, for example, all I see in p_udp.c is
since initial iproute2 import in 2005, apart from some cleanups by
Stephen:

Yes, IP and tcp should be fine. Others were place holders.
Note, there is even no need to change pedit - you could write a bash
script as we did.

static int
parse_udp(int *argc_p, char ***argv_p, struct tc_pedit_sel *sel, struct
tc_pedit_key *tkey)
{
     int res = -1;
     return res;
}

struct m_pedit_util p_pedit_udp = {
     NULL,
     "udp",
     parse_udp,
};

Same for tcp, icmp, ipv6 bits code ... :/ Is it still planned to eventually
complete these?

someone else could run with it; at the moment i think this was ok at
small scale but it hasnt worked well in a larger scale. When you write
other apps (other than tc) to use these APIs parsing all the 32 bit
chunks is more cumbersome then getting a struct which gives me precise
info.

I agree that from a usability PoV, it might be nice to

have some kind of 'pretty printer' for it besides the existing config
parser there (e.g. when we know that a loaded instance was done with a
high-level module, we could annotate that for retrieval on dump or such).

If i could tag the structure with something the kernel then returns to
me when i dump, I could add nice pretty printers (same arguement applies
to u32).
But that doesnt solve the programmability issue as being a good cause.

cheers,
jamal