6 bytes count difference between prism2_tx prism2_rx - Question?

Gavin Yeung gavin at cs.ucla.edu
Fri Jun 6 03:55:32 EDT 2003


Dear all,

I have 2 laptops running hostap in Ad-Hoc mode.  They ping each other
fine.

However to my surprise, the data length value in prism2_tx() and
prism2_rx() in hostap_hw.c are different!

In prism2_tx, right before the call to hfa384x_to_bap, I print skb->len
and find that it is 98.  In prism2_rx, rxdesc.data_len is only 92.  Does
anyone know what accounts for the 6 bytes difference in the receiver
function?

A ping packet should appear at 98 bytes because:
  Ethernet Hdr 14
  IP Hdr       20     
  UDP Hdr       8
  Ping Data    56
  Total      = 98 bytes

Why is rxdesc.data_len in prism2_rx only 92 then?  Does anyone know how
to dump the payload of the packet for examination?

I am using:
  Hostap 0.0.2
  Linksys WPC 11 v3
  NICID: 0x801b v1.0.0
  PRIID: 0x0015 v1.1.0
  STAID: 0x001f v1.4.9
  No WEP

Thank You,
--Gavin



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