"fd->cap_len" for the frame length - or to use macros such as
"BYTES_ARE_IN_FRAME()", "IS_DATA_IN_FRAME()", and "END_OF_FRAME", which
use "pi.captured_len" - so that they correctly handle frames where the
actual data length of the packet is less than the size of the raw frame,
e.g. with encapsulations such as ISL.
svn path=/trunk/; revision=1530