[PATCH Try#14 0/4] Radiotap injection for any Mode

[andy@warmcat.com]

These patches add the ability to inject encapsulated packets down an interface for 
transmission according to a prepended radiotap header.

For injecting packets, the you issue a packet using libpcap or a SOCK_PACKET
socket down an interface to the wireless device that is in any Mode.  The packet
has a 14 byte ethhdr of protocol type ETH_P_80211_RT encapsulating a normal 
radiotap header prepended to the IEEE80211 header and payload.  The radiotap header
is variable length depending on what the user wants to specify, currently the
transmit rate, power and antenna can be specified using normal radiotap semantics.
Any other entries are skipped.

The radiotap parser is broken out into its own file under cfg80211.

A usermode app packetspammer is available from here

http://penumbra.warmcat.com/_twk/tiki-index.php?page=packetspammer
http://git.warmcat.com/?p=packetspammer.git;a=summary

which allows easy injection of these packets from the commandline.  At the moment it
loops issuing packets at a variety of rates which can be seen from another
machine's monitor mode interface on the same channel.  There are instructions for
build and using it on the page above along with Fedora 7 binary and source RPMS.
There is now also a -f switch to allow testing of the FCS flag on injected packets.

Currently it has been tested for both rx and tx using zd1211rw-mac80211.

The patches are based against current wireless-dev.

I also added some documentation files which explains how to use the injection
functionality and radiotap header notes.

Thanks to Michael Wu and Johannes Berg for review and bugfinding.
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