small linux kernel module that creates interface in /proc
for connecting, sending and receiving tcp socket data.

* WARNING: might panic, use in control enviroinment*

* build
    $ git clone https://github.com/jackdoe/hammer
    $ cd hammer && make clean all
    $ sudo insmod hammer

* connecting to something
    $ echo "bzbzb" | nc -l 12345 # start netcat listener on port 12345
    $ sudo echo "127.0.0.1:12345" > /proc/hammer/__control

    you can also specify specify small comments like 
    $ echo "127.0.0.1:12345@some_identifier" > /proc/hammer/__control
    and it will appear in the file

    $ sudo cat /proc/hammer/c_127.0.0.1:12345* 
    # you will see 'bzbzb'
    $ sudo echo "42" > /proc/hammer/c_127.0.0.1:12345*
    # you will see 42 on your netcat console

* /proc/hammer/c_* format:
  c_ip:port_{address of the pointer that is representing the current connection}
    so it looks like: /proc/hammer/c_127.0.0.1:12345_ffff880003d2a700

* aa... everything stays in memory. there is no mechanism for flushing anything,
  only unloading the module. You can define HAMMER_OVERWRITE in hammer.c
  and this will not allocate anything, it will just overwrite 10k buffer in the
  connection structure (that is if you do not care for the whole connection, but
  you only want some stats, like http status codes)

* concept
  + there are no threads
    we just get the sk_buffs from the tcp stack in interrupt context.

  + no multiplexing
    the kernel tcp stack mutiplexes for us, in the codepath 
    driver->ip->tcp->sk_data_ready

  + there is no sleeping, if memory allocation fails we just skip this frame.

  + everything stays in kernel address space, only the last N bytes are coppied
    on /proc/hammer/c_* read request

* /proc/hammer/s_*
   each connection is counting number of HTTP response status codes
   so cat /proc/hammer/s_127.0.0.1\:9200_ffff8801* will give
   [status code] : [number of packets containing HTTP/1.1 {status code}] for example:

   200 : 25342

* license
   free for all