how to check a port is listening in the kernel?

[liudonghua123]

Hi
I am using Android 4.2 which the kernel is 3.0. So I post my question here.
And I want to know how can I get the status of a port in the kernel (I am writing a netfilter kernel module which need to know whether a local proxy is running or not). I know this can be achieve by checking the return value of creating a new socket. But this is too expensive for the socket created is useless.
Any help would be appreciated!
Thanks!

[bsdtux]

I am not sure if this helps but I did find some code using netfilter that wanted to do the same thing. Here is the link
c - Check port number in Linux Kernel Module using Netfilter - Stack Overflow