Johannes Berg wrote:
Hey,
I'm currently working on using radiotap for some stuff in the Linux
wireless stack (mac80211), and ran across the case where we want
userspace to be able to send the frame to a high-priority queue. I'm
thinking this should probably be in radiotap.
There are also other things that need to be controlled via radiotap,
here's what I can propose so far:
* IEEE80211_RADIOTAP_SEND_AC u8 access category
*
* Indicates which access category to send the frame in, 0-3.
*
* IEEE80211_RADIOTAP_SEND_FLAGS u8 flags
*
IEEE80211_RADIOTAP_SEND_FLAG_ENCRYPT (1<<0)
/* encrypt with key for the station named in addr1 or default key */
IEEE80211_RADIOTAP_SEND_FLAG_AUTO_RTSCTS (1<<1)
/* automatically decide whether rts/cts are used, if unset then
* rts/cts are used depending on IEEE80211_RADIOTAP_F_TX_{CTS,RTS} */
IEEE80211_RADIOTAP_SEND_FLAG_RATE_CONTROL (1<<2)
/* should rate control be applied to this algorithm? if not, take
* the value of IEEE80211_RADIOTAP_RATE or lowest rate */
IEEE80211_RADIOTAP_SEND_FLAG_SEQNR (1<<3)
/* set if the sequence number in the packet shouldn't be changed,
* if not set then the packet is sequence numbered properly */
So far that's all I would need, but some regular fields would also be
used like I said above for example IEEE80211_RADIOTAP_F_TX_{CTS,RTS}. A
good text on using radiotap for this purpose should probably be written,
I think somebody other than Andy and me was working on something like
this so we really should work together and define this properly.
This is the control state available on FreeBSD for doing raw 802.11
frame xmit (packets need not include all this; I've just provided the
most complete set of knobs):
uint8_t ibp_flags;
#define IEEE80211_BPF_SHORTPRE 0x01 /* tx with short preamble */
#define IEEE80211_BPF_NOACK 0x02 /* tx with no ack */
#define IEEE80211_BPF_CRYPTO 0x04 /* tx with h/w encryption */
#define IEEE80211_BPF_FCS 0x10 /* frame incldues FCS */
#define IEEE80211_BPF_DATAPAD 0x20 /* frame includes data padding */
#define IEEE80211_BPF_RTS 0x40 /* tx with RTS/CTS */
#define IEEE80211_BPF_CTS 0x80 /* tx with CTS only */
uint8_t ibp_pri; /* WME/WMM AC+tx antenna */
uint8_t ibp_try0; /* series 1 try count */
uint8_t ibp_rate0; /* series 1 IEEE tx rate */
uint8_t ibp_power; /* tx power (device units) */
uint8_t ibp_ctsrate; /* IEEE tx rate for CTS */
uint8_t ibp_try1; /* series 2 try count */
uint8_t ibp_rate1; /* series 2 IEEE tx rate */
uint8_t ibp_try2; /* series 3 try count */
uint8_t ibp_rate2; /* series 3 IEEE tx rate */
uint8_t ibp_try3; /* series 4 try count */
uint8_t ibp_rate3; /* series 4 IEEE tx rate */
Note that using a monitor mode interface for transmit is a bad idea. It
is likely you will encounter devices that disallow any packet transmit
when operating in monitor mode. In practice this can be worked around
by using a non-monitor operating mode for the device (e.g. adhoc mode
w/o setting up beacons) but exporting this notion to user mode is bad
IMO. In net80211 there is an adhoc-demo mode which is essentially adhoc
mode which was originally added for functionality found in old lucent
cards but more recently has been used for building applications that
want a "raw 802.11 device".
Sam
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