Netlink Protocol Format (RFC3549)
+-----------------+-+-------------------+-+
|Netlink Message  |P| Generic Netlink   |P|
|    Header       |A|  Message Header   |A|
|(struct nlmsghdr)|D|(struct genlmsghdr)|D|
+-----------------+-+-------------------+-+
+-----------------+-+-----------------+-+-----------------+-+-----------------+-+---+
|Netlink Attribute|P|Netlink Attribute|P|Netlink Attribute|P|Netlink Attribute|P|...|
|    #0 Header    |A|   #0 Payload    |A|   #1 Header     |A|   #1 Payload    |A|   |
| (struct nlattr) |D|     (void)      |D| (struct nlattr) |D|     (void)      |D|   |
+-----------------+-+-----------------+-+-----------------+-+-----------------+-+---+

* Each netlink message consists of a bitstream with a netlink header.
* After this header a second header *can* be used specific to the netlink
  family in use. This library was tested using the generic netlink
  protocol defined by struct genlmsghdr to support nl80211.
* After the header(s) netlink attributes can be appended to the message
  which hold can hold basic types such as unsigned integers and strings.
* All data structures in this implementation are byte-aligned (Currently 4 bytes).
* Acknowledgements (ACKs) are sent as NLMSG_ERROR netlink message types (0x2) and
  have an error value of 0.

KNOWN BUGS
* NOT THREAD SAFE!!!
* nla_parse - does not use nla_policy argument
* nl_recvmsgs - does not support nl_cb_overwrite_recv()
* nl_recv - sets/unsets async. flag
* genl_ctrl_alloc_cache - netlink send/recv funcs should be used

REFERENCES
* nl80211.h
* netlink_types.h
* $LINUX_KERNEL/net/wireless/nl80211.c
* http://www.infradead.org/~tgr/libnl/doc-3.0/index.html
* http://www.netfilter.org/projects/libmnl/doxygen/index.html