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[X25]: Fast select with no restriction on response

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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>
This commit is contained in:
Shaun Pereira
2005-06-22 22:16:17 -07:00
committed by David S. Miller
parent cb65d506c3
commit ebc3f64b86
5 changed files with 86 additions and 16 deletions
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23
net/x25/x25_subr.c
View File

@@ -19,6 +19,8 @@
* mar/20/00 Daniela Squassoni Disabling/enabling of facilities
* negotiation.
* jun/24/01 Arnaldo C. Melo use skb_queue_purge, cleanups
* apr/04/15 Shaun Pereira Fast select with no
* restriction on response.
*/
#include <linux/kernel.h>
@@ -127,8 +129,12 @@ void x25_write_internal(struct sock *sk, int frametype)
len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN +
X25_MAX_CUD_LEN;
break;
case X25_CALL_ACCEPTED:
len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */
if(x25->facilities.reverse & 0x80) {
len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
} else {
len += 1 + X25_MAX_FAC_LEN;
}
break;
case X25_CLEAR_REQUEST:
case X25_RESET_REQUEST:
@@ -203,9 +209,16 @@ void x25_write_internal(struct sock *sk, int frametype)
x25->vc_facil_mask);
dptr = skb_put(skb, len);
memcpy(dptr, facilities, len);
dptr = skb_put(skb, x25->calluserdata.cudlength);
memcpy(dptr, x25->calluserdata.cuddata,
x25->calluserdata.cudlength);
/* fast select with no restriction on response
allows call user data. Userland must
ensure it is ours and not theirs */
if(x25->facilities.reverse & 0x80) {
dptr = skb_put(skb,
x25->calluserdata.cudlength);
memcpy(dptr, x25->calluserdata.cuddata,
x25->calluserdata.cudlength);
}
x25->calluserdata.cudlength = 0;
break;