Allows use of the optional user facility to insert ITU-T
(http://www.itu.int/ITU-T/) specified DTE facilities in call set-up x25
packets.  This feature is optional; no facilities will be added if the ioctl
is not used, and call setup packet remains the same as before.

If the ioctls provided by the patch are used, then a facility marker will be
added to the x25 packet header so that the called dte address extension
facility can be differentiated from other types of facilities (as described in
the ITU-T X.25 recommendation) that are also allowed in the x25 packet header.

Facility markers are made up of two octets, and may be present in the x25
packet headers of call-request, incoming call, call accepted, clear request,
and clear indication packets.  The first of the two octets represents the
facility code field and is set to zero by this patch.  The second octet of the
marker represents the facility parameter field and is set to 0x0F because the
marker will be inserted before ITU-T type DTE facilities.

Since according to ITU-T X.25 Recommendation X.25(10/96)- 7.1 "All networks
will support the facility markers with a facility parameter field set to all
ones or to 00001111", therefore this patch should work with all x.25 networks.

While there are many ITU-T DTE facilities, this patch implements only the
called and calling address extension, with placeholders in the
x25_dte_facilities structure for the rest of the facilities.

Testing:

This patch was tested using a cisco xot router connected on its serial ports
to an X.25 network, and on its lan ports to a host running an xotd daemon.

It is also possible to test this patch using an xotd daemon and an x25tap
patch, where the xotd daemons work back-to-back without actually using an x.25
network.  See www.fyonne.net for details on how to do this.
Signed-off-by: NShaun Pereira <spereira@tusc.com.au>
Acked-by: NAndrew Hendry <ahendry@tusc.com.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch is a follow up to patch 1 regarding "Selective Sub Address
matching with call user data".  It allows use of the Fast-Select-Acceptance
optional user facility for X.25.

This patch just implements fast select with no restriction on response
(NRR).  What this means (according to ITU-T Recomendation 10/96 section
6.16) is that if in an incoming call packet, the relevant facility bits are
set for fast-select-NRR, then the called DTE can issue a direct response to
the incoming packet using a call-accepted packet that contains
call-user-data.  This patch allows such a response.  

The called DTE can also respond with a clear-request packet that contains
call-user-data.  However, this feature is currently not implemented by the
patch.

How is Fast Select Acceptance used?
By default, the system does not allow fast select acceptance (as before).
To enable a response to fast select acceptance,  
After a listen socket in created and bound as follows
	socket(AF_X25, SOCK_SEQPACKET, 0);
	bind(call_soc, (struct sockaddr *)&locl_addr, sizeof(locl_addr));
but before a listen system call is made, the following ioctl should be used.
	ioctl(call_soc,SIOCX25CALLACCPTAPPRV);
Now the listen system call can be made
	listen(call_soc, 4);
After this, an incoming-call packet will be accepted, but no call-accepted 
packet will be sent back until the following system call is made on the socket
that accepts the call
	ioctl(vc_soc,SIOCX25SENDCALLACCPT);
The network (or cisco xot router used for testing here) will allow the 
application server's call-user-data in the call-accepted packet, 
provided the call-request was made with Fast-select NRR.
Signed-off-by: NShaun Pereira <spereira@tusc.com.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!