Communication between kernel and userspace via local socket

[Maxim Ignatenko]

Julian Elischer wrote:

> On 11/16/11 12:55 AM, Ed Schouten wrote:
>> * Maxim Ignatenko<gelraen.ua at gmail.com>, 20111115 21:18:
>>> I'm currently inventing the wheel^W^W^Wwriting a firewall from scratch and
>>> looking for most convenient way to establish communication between
>>> userspace processes and kernel part. Communication pattern best fits to
>>> listening PF_LOCAL socket opened from kernel and userspace processes
>>> connecting to it.
>> What's wrong with a character device?
> 
> you can't easily have a different character device depending on which
> jail you are in..
> (well, you can but it gets tricky).. see the problem with /dev/pflog
> and vimages.
> 
> 
> Maxim, look at the usage of sockets with netgraph ng_socket node..  also
> divert sockets.
> 

Did you meant ng_ksocket? I've looked on it, but in case of ng_ksocket 
connections accepted upon receiving control message NGM_KSOCKET_ACCEPT, but I 
need to accept connections without such "punch". As far as I understand, I 
need to spawn kernel process or thread which will listen for incoming 
connections and respond to requests, just like normal network daemon does, but 
I don't know how to do this.
divert(4) will not do the job, since packets written to divert socket goes to 
IP stack.