On Thu, Dec 18, 2003 at 01:09:24AM +0100, Jan Kiszka wrote:
> based on the work of Shaun Jackman, I started some months ago a new
> approach to implement a dissector plugin which is able to analyze
> infrared communication according to the IrDA specification.
The IrLAP V1.1 specification gives, for the XID command, 0x2F (with the
P/F bit ORed in); for the XID response, it gives 0xAF (again, with the
P/F bit ORed in).
However, that spec says IrLAP is "based on pre-existing standard
asynchronous HDLC and SDLC half duplex protocols as used on multi-drop
links (see references)", and one of the references is to ISO 4335
(HDLC).
4335 has been withdrawn and replaced by ISO/IEC 13239:2002, which gives
as the encoding for XID commands and responses 0xAF (with the P/F bit ORed)
in.
Does IrLAP really use a different encoding for XID commands than does
HDLC? (0x2F, in HDLC, is SABM.) Or is that a typo in the spec? It's
not mentioned in the IrLAP V1.1 Errata for March 2003. Were it not for
that, the IrDA dissector could, I think, use the
"dissect_xdlc_control()" routine in xdlc.c (the current CVS version,
that is, which supports named fields for the subfields of the control
field).
