[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>
diff --git a/net/x25/x25_subr.c b/net/x25/x25_subr.c
index c349bbd..7fd872ad 100644
--- a/net/x25/x25_subr.c
+++ b/net/x25/x25_subr.c
@@ -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 @@
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 @@
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;