Query about recent Radiotap changes

Query about recent Radiotap changes

[Scott Raynel]

Hi!

Just noticed the changes that went into OpenBSD tonight, but I have a  
query as to one of the comments in the file:

/* For IEEE80211_RADIOTAP_RX_FLAGS */
#define IEEE80211_RADIOTAP_F_RX_BADFCS 0x0001  /* Frame failed CRC  
check.
						*
						* Deprecated: use the flag
						* IEEE80211_RADIOTAP_F_FCS in
						* the IEEE80211_RADIOTAP_FLAGS
						* field, instead.
						*/

/* For IEEE80211_RADIOTAP_TX_FLAGS */

What does the Deprecated warning apply to? I presume it's got to do  
with the old field, IEEE80211_RADIOTAP_FCS, but the comment is in an  
extremely weird place. It implies that the new _F_RX_BADFCS flag is  
deprecated.

Cheers,

--
Scott Raynel
WAND Network Research Group
Department of Computer Science
University of Waikato
New Zealand

Re: Query about recent Radiotap changes

[David Young]

On Mon, Mar 26, 2007 at 09:35:24PM +1200, Scott Raynel wrote:
> Hi!
> 
> Just noticed the changes that went into OpenBSD tonight, but I have a  
> query as to one of the comments in the file:
> 
> /* For IEEE80211_RADIOTAP_RX_FLAGS */
> #define IEEE80211_RADIOTAP_F_RX_BADFCS 0x0001  /* Frame failed CRC  
> check.
> 						*
> 						* Deprecated: use the flag
> 						* IEEE80211_RADIOTAP_F_FCS in
> 						* the 
> 						IEEE80211_RADIOTAP_FLAGS
> 						* field, instead.
> 						*/
> 
> /* For IEEE80211_RADIOTAP_TX_FLAGS */
> 
> What does the Deprecated warning apply to? I presume it's got to do  
> with the old field, IEEE80211_RADIOTAP_FCS, but the comment is in an  
> extremely weird place. It implies that the new _F_RX_BADFCS flag is  
> deprecated.

The _F_RX_BADFCS flag in the field IEEE80211_RADIOTAP_RX_FLAGS is
redundant.  The flag duplicates the function of the _F_FCS field in
the IEEE80211_RADIOTAP_FLAGS field.  TIMTOWTDI is a recipe for design
complexity.

The reasons I add the four new fields are three-fold:

        * keep my word that those fields would become part of the standard
        * standardize an existing practice that apparently came to
          be due to an innocent misunderstanding between myself and
          another developer
        * create a basis for adding new fields: the next available
	  type number is 18.

You could say these fields became part of the standard through the first
and last radiotap fields amnesty.  I am not 

Dave

-- 
David Young             OJC Technologies
dyoung-eZodSLrBbDpBDgjK7y7TUQ@public.gmane.org      Urbana, IL * (217) 278-3933

Re: Query about recent Radiotap changes

[David Young]

On Mon, Mar 26, 2007 at 02:50:45PM -0500, David Young wrote:
> You could say these fields became part of the standard through the first
> and last radiotap fields amnesty.  I am not 

going to finish that sentence, apparently.

Dave

-- 
David Young             OJC Technologies
dyoung-eZodSLrBbDpBDgjK7y7TUQ@public.gmane.org      Urbana, IL * (217) 278-3933

Re: Query about recent Radiotap changes

[Scott Raynel]

Hello again,

On 27/03/2007, at 7:50 AM, David Young wrote:

>
> The _F_RX_BADFCS flag in the field IEEE80211_RADIOTAP_RX_FLAGS is
> redundant.  The flag duplicates the function of the _F_FCS field in
> the IEEE80211_RADIOTAP_FLAGS field.  TIMTOWTDI is a recipe for design
> complexity.

I was under the impression that IEEE80211_RADIOTAP_F_RX_BADFCS  
duplicated the function of the _F_BADFCS, not _F_FCS, which indicates  
the presence of FCS bytes in the frame. Or am I missing something?

Cheers,

--
Scott Raynel
WAND Network Research Group
Department of Computer Science
University of Waikato
New Zealand

Re: Query about recent Radiotap changes

[David Young]

On Tue, Mar 27, 2007 at 09:11:17AM +1200, Scott Raynel wrote:
> Hello again,
> 
> On 27/03/2007, at 7:50 AM, David Young wrote:
> 
> >
> >The _F_RX_BADFCS flag in the field IEEE80211_RADIOTAP_RX_FLAGS is
> >redundant.  The flag duplicates the function of the _F_FCS field in
> >the IEEE80211_RADIOTAP_FLAGS field.  TIMTOWTDI is a recipe for design
> >complexity.
> 
> I was under the impression that IEEE80211_RADIOTAP_F_RX_BADFCS  
> duplicated the function of the _F_BADFCS, not _F_FCS, which indicates  
> the presence of FCS bytes in the frame. Or am I missing something?

You're right.  It duplicates the _F_BADFCS flag, not _F_FCS.

Dave

-- 
David Young             OJC Technologies
dyoung-eZodSLrBbDpBDgjK7y7TUQ@public.gmane.org      Urbana, IL * (217) 278-3933