Hi Justin,
The expectation until now has been that options are not parsed until hitting
the tcp related nodes. If tcp_options_parse is enough, then make it public and
use it. That function just expects a tcp_options_t struct for outputting the
results so no need for a tcp_connection_t. Now, if you need your special
function to both read, match and update in place the options, then I recommend
you write your own options parser.
Hope this helps,
Florin
> On Nov 14, 2017, at 5:13 AM, Justin Iurman <justin.iur...@uliege.be> wrote:
>
> Hi Dave,
>
> Thanks (again) for your reply.
>
>> Brief commercial: hopefully you added your node to the ip4 unicast feature
>> arc,
>> configured to grab pkts, pre-ip4/6-lookup.
>
> Indeed, I added my node to the ip4-unicast feature arc.
>
>> In feature-arc land, the following one-liner sets next0 so pkts will visit
>> the
>> next enabled feature. The last node in the ip4-unicast feature arc is
>> ip4-lookup...
>>
>> /* Next node in unicast feature arc */
>> vnet_get_config_data (em->config_main[table_index],
>> &b0->current_config_index, &next0,
>> /* # bytes of config data */ 0);
>>
>> Check the ip protocol and ignore any non-TCP pkts:
>>
>> ip40 = vlib_buffer_get_current (b0);
>> if (ip40->protocol != IP_PROTOCOL_TCP)
>> goto trace0;
>>
>> Then use ip4_next_header() to find the tcp layer, etc. etc.
>
> Actually, I'm already able to access L3 and L4 structures. But, when I have
> the following, for instance:
>
> ip40 = vlib_buffer_get_current (b0);
> if (ip40->protocol == IP_PROTOCOL_TCP)
> {
> tcp_header_t *tcp = ip4_next_header(ip40);
> // where are options (tcp_options_t) ?
> }
>
> How am I able to access TCP options for each packet ? I mean, I could
> directly parse them by moving the data pointer but I've also seen a function
> called tcp_options_parse (see my previous email) that already does this job.
> How would you proceed to do this ? The expected behavior is to match some
> options and strip them.
>
> Thanks,
>
> Justin
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