[ovs-discuss] Adding a new OpenFlow action to ovs, ctx->xin->packet is null

Christian Stigen Larsen cslarsen at gmail.com
Sat May 10 16:11:29 UTC 2014


Ben Pfaff <blp at nicira.com>:
>> Is do_xlate_actions ("translate actions"?) the wrong place for this kind of
>> stuff?  How can I get a pointer to the raw packet data?
> 
> Usually, ofproto-dpif-xlate should not actually implement the OpenFlow
> actions.

Sorry for being trigger-happy, but even if I chose to implement datapath
actions, how can I inspect the packet data?  For some reason I get a
NULL-pointer in ctx->xin->packet, while, e.g., OFPACT_OUTPUT in
do_xlate_actions gets the full packet.

The idea being that I could read some parameters and then install
several datapath actions based on these.

I install the flow using

ovs-ofctl add-flow S2 idle_timeout=20,dl_type=0x7a01,actions=foo:123

It trigs on a packet with this ethernet type, but I get null pointers in both
translate calls per packet.

I've got a pretty good debug environment set up now, so I'll continue
digging and check out the stuff you suggested.

Regards,

-- 
Christian Stigen Larsen


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