[X25]: Fast select with no restriction on response
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: Shaun Pereira <spereira@tusc.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
5 files changed