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>
From: Shaun Pereira <spereira@tusc.com.au>
This is the first (independent of the second) patch of two that I am
working on with x25 on linux (tested with xot on a cisco router). Details
are as follows.
Current state of module:
A server using the current implementation (2.6.11.7) of the x25 module will
accept a call request/ incoming call packet at the listening x.25 address,
from all callers to that address, as long as NO call user data is present
in the packet header.
If the server needs to choose to accept a particular call request/ incoming
call packet arriving at its listening x25 address, then the kernel has to
allow a match of call user data present in the call request packet with its
own. This is required when multiple servers listen at the same x25 address
and device interface. The kernel currently matches ALL call user data, if
present.
Current Changes:
This patch is a follow up to the patch submitted previously by Andrew
Hendry, and allows the user to selectively control the number of octets of
call user data in the call request packet, that the kernel will match. By
default no call user data is matched, even if call user data is present.
To allow call user data matching, a cudmatchlength > 0 has to be passed
into the kernel after which the passed number of octets will be matched.
Otherwise the kernel behavior is exactly as the original implementation.
This patch also ensures that as is normally the case, no call user data
will be present in the Call accepted / call connected packet sent back to
the caller
Future Changes on next patch:
There are cases however when call user data may be present in the call
accepted packet. According to the X.25 recommendation (ITU-T 10/96)
section 5.2.3.2 call user data may be present in the call accepted packet
provided the fast select facility is used. My next patch will include this
fast select utility and the ability to send up to 128 octets call user data
in the call accepted packet provided the fast select facility is used. I
am currently testing this, again with xot on linux and cisco.
Signed-off-by: Shaun Pereira <spereira@tusc.com.au>
(With a fix from Alexey Dobriyan <adobriyan@gmail.com>)
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David 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!
Shaun Pereira