[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>

2 files changed, 6 insertions, 2 deletions

diff --git a/include/linux/x25.h b/include/linux/x25.h
index 6f43b3d20248..16d44931afa0 100644
--- a/include/linux/x25.h
+++ b/include/linux/x25.h
@@ -19,6 +19,8 @@
 #define SIOCX25SCALLUSERDATA    (SIOCPROTOPRIVATE + 5)
 #define SIOCX25GCAUSEDIAG       (SIOCPROTOPRIVATE + 6)
 #define SIOCX25SCUDMATCHLEN     (SIOCPROTOPRIVATE + 7)
+#define SIOCX25CALLACCPTAPPRV   (SIOCPROTOPRIVATE + 8)
+#define SIOCX25SENDCALLACCPT    (SIOCPROTOPRIVATE + 9)
 
 /*
  *      Values for {get,set}sockopt.
diff --git a/include/net/x25.h b/include/net/x25.h
index 9dd70dd4a9b7..8b39b98876e8 100644
--- a/include/net/x25.h
+++ b/include/net/x25.h
@@ -79,6 +79,8 @@ enum {
 #define X25_DEFAULT_PACKET_SIZE X25_PS128               /* Default Packet Size */
 #define X25_DEFAULT_THROUGHPUT  0x0A                    /* Deafult Throughput */
 #define X25_DEFAULT_REVERSE     0x00                    /* Default Reverse Charging */
+#define X25_DENY_ACCPT_APPRV   0x01                     /* Default value */
+#define X25_ALLOW_ACCPT_APPRV  0x00                     /* Control enabled */
 
 #define X25_SMODULUS            8
 #define X25_EMODULUS            128
@@ -94,7 +96,7 @@ enum {
 #define X25_FAC_CLASS_C         0x80
 #define X25_FAC_CLASS_D         0xC0
 
-#define X25_FAC_REVERSE         0x01
+#define X25_FAC_REVERSE         0x01                    /* also fast select */
 #define X25_FAC_THROUGHPUT      0x02
 #define X25_FAC_PACKET_SIZE     0x42
 #define X25_FAC_WINDOW_SIZE     0x43
@@ -135,7 +137,7 @@ struct x25_sock {
         struct x25_address      source_addr, dest_addr;
         struct x25_neigh        *neighbour;
         unsigned int            lci, cudmatchlength;
-        unsigned char           state, condition, qbitincl, intflag;
+        unsigned char           state, condition, qbitincl, intflag, accptapprv;
         unsigned short          vs, vr, va, vl;
         unsigned long           t2, t21, t22, t23;
         unsigned short          fraglen;