[X25]: allow ITU-T DTE facilities for x25

Allows use of the optional user facility to insert ITU-T
(http://www.itu.int/ITU-T/) specified DTE facilities in call set-up x25
packets. This feature is optional; no facilities will be added if the ioctl
is not used, and call setup packet remains the same as before.

If the ioctls provided by the patch are used, then a facility marker will be
added to the x25 packet header so that the called dte address extension
facility can be differentiated from other types of facilities (as described in
the ITU-T X.25 recommendation) that are also allowed in the x25 packet header.

Facility markers are made up of two octets, and may be present in the x25
packet headers of call-request, incoming call, call accepted, clear request,
and clear indication packets. The first of the two octets represents the
facility code field and is set to zero by this patch. The second octet of the
marker represents the facility parameter field and is set to 0x0F because the
marker will be inserted before ITU-T type DTE facilities.

Since according to ITU-T X.25 Recommendation X.25(10/96)- 7.1 "All networks
will support the facility markers with a facility parameter field set to all
ones or to 00001111", therefore this patch should work with all x.25 networks.

While there are many ITU-T DTE facilities, this patch implements only the
called and calling address extension, with placeholders in the
x25_dte_facilities structure for the rest of the facilities.

Testing:

This patch was tested using a cisco xot router connected on its serial ports
to an X.25 network, and on its lan ports to a host running an xotd daemon.

It is also possible to test this patch using an xotd daemon and an x25tap
patch, where the xotd daemons work back-to-back without actually using an x.25
network. See www.fyonne.net for details on how to do this.

Signed-off-by: Shaun Pereira <[e-mail]>
Acked-by: Andrew Hendry <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/x25.h

···
 #ifndef	X25_KERNEL_H
 #define	X25_KERNEL_H
 
+#include <linux/types.h>
+
 #define	SIOCX25GSUBSCRIP	(SIOCPROTOPRIVATE + 0)
 #define	SIOCX25SSUBSCRIP	(SIOCPROTOPRIVATE + 1)
 #define	SIOCX25GFACILITIES	(SIOCPROTOPRIVATE + 2)
···
 #define SIOCX25SCUDMATCHLEN	(SIOCPROTOPRIVATE + 7)
 #define SIOCX25CALLACCPTAPPRV   (SIOCPROTOPRIVATE + 8)
 #define SIOCX25SENDCALLACCPT    (SIOCPROTOPRIVATE + 9)
+#define SIOCX25GDTEFACILITIES (SIOCPROTOPRIVATE + 10)
+#define SIOCX25SDTEFACILITIES (SIOCPROTOPRIVATE + 11)
 
 /*
  *	Values for {get,set}sockopt.
···
 #define	X25_MASK_PACKET_SIZE	0x04
 #define	X25_MASK_WINDOW_SIZE	0x08
 
+#define X25_MASK_CALLING_AE 0x10
+#define X25_MASK_CALLED_AE 0x20
 
 
 /*
···
 	unsigned int	pacsize_in, pacsize_out;
 	unsigned int	throughput;
 	unsigned int	reverse;
+};
+
+/*
+* ITU DTE facilities
+* Only the called and calling address
+* extension are currently implemented.
+* The rest are in place to avoid the struct
+* changing size if someone needs them later
+*/
+
+struct x25_dte_facilities {
+	__u16 delay_cumul;
+	__u16 delay_target;
+	__u16 delay_max;
+	__u8 min_throughput;
+	__u8 expedited;
+	__u8 calling_len;
+	__u8 called_len;
+	__u8 calling_ae[20];
+	__u8 called_ae[20];
 };
 
 /*

include/net/x25.h

···
 #define	X25_FAC_PACKET_SIZE	0x42
 #define	X25_FAC_WINDOW_SIZE	0x43
 
-#define	X25_MAX_FAC_LEN		20		/* Plenty to spare */
+#define X25_MAX_FAC_LEN 	60
 #define	X25_MAX_CUD_LEN		128
+
+#define X25_FAC_CALLING_AE 	0xCB
+#define X25_FAC_CALLED_AE 	0xC9
+
+#define X25_MARKER 		0x00
+#define X25_DTE_SERVICES 	0x0F
+#define X25_MAX_AE_LEN 		40			/* Max num of semi-octets in AE - OSI Nw */
+#define X25_MAX_DTE_FACIL_LEN	21			/* Max length of DTE facility params */
 
 /**
  *	struct x25_route - x25 routing entry
···
 	struct timer_list	timer;
 	struct x25_causediag	causediag;
 	struct x25_facilities	facilities;
+	struct x25_dte_facilities dte_facilities;
 	struct x25_calluserdata	calluserdata;
 	unsigned long 		vc_facil_mask;	/* inc_call facilities mask */
 };
···
 extern void x25_terminate_link(struct x25_neigh *);
 
 /* x25_facilities.c */
-extern int  x25_parse_facilities(struct sk_buff *, struct x25_facilities *, unsigned long *);
-extern int  x25_create_facilities(unsigned char *, struct x25_facilities *, unsigned long);
-extern int  x25_negotiate_facilities(struct sk_buff *, struct sock *, struct x25_facilities *);
+extern int x25_parse_facilities(struct sk_buff *, struct x25_facilities *,
+				struct x25_dte_facilities *, unsigned long *);
+extern int x25_create_facilities(unsigned char *, struct x25_facilities *,
+				struct x25_dte_facilities *, unsigned long);
+extern int x25_negotiate_facilities(struct sk_buff *, struct sock *,
+				struct x25_facilities *,
+				struct x25_dte_facilities *);
 extern void x25_limit_facilities(struct x25_facilities *, struct x25_neigh *);
 
 /* x25_in.c */

net/x25/af_x25.c

···
 	x25->facilities.pacsize_out = X25_DEFAULT_PACKET_SIZE;
 	x25->facilities.throughput  = X25_DEFAULT_THROUGHPUT;
 	x25->facilities.reverse     = X25_DEFAULT_REVERSE;
+ 	x25->dte_facilities.calling_len = 0;
+ 	x25->dte_facilities.called_len = 0;
+ 	memset(x25->dte_facilities.called_ae, '\0',
+		 	sizeof(x25->dte_facilities.called_ae));
+ 	memset(x25->dte_facilities.calling_ae, '\0',
+		 	sizeof(x25->dte_facilities.calling_ae));
+
 	rc = 0;
 out:
 	return rc;
···
 	x25->t2         = ox25->t2;
 	x25->facilities = ox25->facilities;
 	x25->qbitincl   = ox25->qbitincl;
+	x25->dte_facilities = ox25->dte_facilities;
 	x25->cudmatchlength = ox25->cudmatchlength;
 	x25->accptapprv = ox25->accptapprv;
 
···
 	struct x25_sock *makex25;
 	struct x25_address source_addr, dest_addr;
 	struct x25_facilities facilities;
+	struct x25_dte_facilities dte_facilities;
 	int len, rc;
 
 	/*
···
 	/*
 	 *	Try to reach a compromise on the requested facilities.
 	 */
-	if ((len = x25_negotiate_facilities(skb, sk, &facilities)) == -1)
+	len = x25_negotiate_facilities(skb, sk, &facilities, &dte_facilities);
+	if (len == -1)
 		goto out_sock_put;
 
 	/*
···
 	makex25->source_addr   = source_addr;
 	makex25->neighbour     = nb;
 	makex25->facilities    = facilities;
+	makex25->dte_facilities= dte_facilities;
 	makex25->vc_facil_mask = x25_sk(sk)->vc_facil_mask;
 	/* ensure no reverse facil on accept */
 	makex25->vc_facil_mask &= ~X25_MASK_REVERSE;
+	/* ensure no calling address extension on accept */
+	makex25->vc_facil_mask &= ~X25_MASK_CALLING_AE;
 	makex25->cudmatchlength = x25_sk(sk)->cudmatchlength;
 
 	/* Normally all calls are accepted immediatly */
···
 				(facilities.reverse | 0x81)!= 0x81)
 				break;
 			x25->facilities = facilities;
+			rc = 0;
+			break;
+		}
+
+		case SIOCX25GDTEFACILITIES: {
+ 			rc = copy_to_user(argp, &x25->dte_facilities,
+						sizeof(x25->dte_facilities));
+			if (rc)
+				rc = -EFAULT;
+ 			break;
+ 		}
+
+	 	case SIOCX25SDTEFACILITIES: {
+	 		struct x25_dte_facilities dtefacs;
+	 		rc = -EFAULT;
+		 	if (copy_from_user(&dtefacs, argp, sizeof(dtefacs)))
+				break;
+			rc = -EINVAL;
+			if (sk->sk_state != TCP_LISTEN &&
+					sk->sk_state != TCP_CLOSE)
+				break;
+			if (dtefacs.calling_len > X25_MAX_AE_LEN)
+				break;
+			if (dtefacs.calling_ae == NULL)
+				break;
+			if (dtefacs.called_len > X25_MAX_AE_LEN)
+				break;
+			if (dtefacs.called_ae == NULL)
+				break;
+			x25->dte_facilities = dtefacs;
 			rc = 0;
 			break;
 		}

net/x25/x25_facilities.c

···
 #include <net/x25.h>
 
 /*
- *	Parse a set of facilities into the facilities structure. Unrecognised
+ * Parse a set of facilities into the facilities structures. Unrecognised
  *	facilities are written to the debug log file.
  */
-int x25_parse_facilities(struct sk_buff *skb,
-			 struct x25_facilities *facilities,
-			 unsigned long *vc_fac_mask)
+int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities,
+		struct x25_dte_facilities *dte_facs, unsigned long *vc_fac_mask)
 {
 	unsigned char *p = skb->data;
 	unsigned int len = *p++;
 
 	*vc_fac_mask = 0;
+
+	/*
+	 * The kernel knows which facilities were set on an incoming call but
+	 * currently this information is not available to userspace.  Here we
+	 * give userspace who read incoming call facilities 0 length to indicate
+	 * it wasn't set.
+	 */
+	dte_facs->calling_len = 0;
+	dte_facs->called_len = 0;
+	memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae));
+	memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae));
 
 	while (len > 0) {
 		switch (*p & X25_FAC_CLASS_MASK) {
···
 			case X25_FAC_THROUGHPUT:
 				facilities->throughput = p[1];
 				*vc_fac_mask |= X25_MASK_THROUGHPUT;
+				break;
+			case X25_MARKER:
 				break;
 			default:
 				printk(KERN_DEBUG "X.25: unknown facility "
···
 			len -= 4;
 			break;
 		case X25_FAC_CLASS_D:
-			printk(KERN_DEBUG "X.25: unknown facility %02X, "
-			       "length %d, values %02X, %02X, %02X, %02X\n",
-			       p[0], p[1], p[2], p[3], p[4], p[5]);
+			switch (*p) {
+	 		case X25_FAC_CALLING_AE:
+	 			if (p[1] > X25_MAX_DTE_FACIL_LEN)
+					break;
+				dte_facs->calling_len = p[2];
+				memcpy(dte_facs->calling_ae, &p[3], p[1] - 1);
+				*vc_fac_mask |= X25_MASK_CALLING_AE;
+				break;
+			case X25_FAC_CALLED_AE:
+				if (p[1] > X25_MAX_DTE_FACIL_LEN)
+					break;
+				dte_facs->called_len = p[2];
+				memcpy(dte_facs->called_ae, &p[3], p[1] - 1);
+				*vc_fac_mask |= X25_MASK_CALLED_AE;
+				break;
+			default:
+				printk(KERN_DEBUG "X.25: unknown facility %02X,"
+					"length %d, values %02X, %02X, "
+					"%02X, %02X\n",
+					p[0], p[1], p[2], p[3], p[4], p[5]);
+				break;
+			}
 			len -= p[1] + 2;
-			p   += p[1] + 2;
+			p += p[1] + 2;
 			break;
 		}
 	}
···
  *	Create a set of facilities.
  */
 int x25_create_facilities(unsigned char *buffer,
-			  struct x25_facilities *facilities,
-			  unsigned long facil_mask)
+		struct x25_facilities *facilities,
+		struct x25_dte_facilities *dte_facs, unsigned long facil_mask)
 {
 	unsigned char *p = buffer + 1;
 	int len;
···
 		*p++ = facilities->winsize_out ? : facilities->winsize_in;
 	}
 
+	if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) {
+		*p++ = X25_MARKER;
+		*p++ = X25_DTE_SERVICES;
+	}
+
+	if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) {
+		unsigned bytecount = (dte_facs->calling_len % 2) ?
+					dte_facs->calling_len / 2 + 1 :
+					dte_facs->calling_len / 2;
+		*p++ = X25_FAC_CALLING_AE;
+		*p++ = 1 + bytecount;
+		*p++ = dte_facs->calling_len;
+		memcpy(p, dte_facs->calling_ae, bytecount);
+		p += bytecount;
+	}
+
+	if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) {
+		unsigned bytecount = (dte_facs->called_len % 2) ?
+		dte_facs->called_len / 2 + 1 :
+		dte_facs->called_len / 2;
+		*p++ = X25_FAC_CALLED_AE;
+		*p++ = 1 + bytecount;
+		*p++ = dte_facs->called_len;
+		memcpy(p, dte_facs->called_ae, bytecount);
+		p+=bytecount;
+	}
+
 	len       = p - buffer;
 	buffer[0] = len - 1;
 
···
  *	The only real problem is with reverse charging.
  */
 int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk,
-			     struct x25_facilities *new)
+		struct x25_facilities *new, struct x25_dte_facilities *dte)
 {
 	struct x25_sock *x25 = x25_sk(sk);
 	struct x25_facilities *ours = &x25->facilities;
···
 	memset(&theirs, 0, sizeof(theirs));
 	memcpy(new, ours, sizeof(*new));
 
-	len = x25_parse_facilities(skb, &theirs, &x25->vc_facil_mask);
+	len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask);
 
 	/*
 	 *	They want reverse charging, we won't accept it.

net/x25/x25_in.c

···
 			skb_pull(skb, x25_addr_ntoa(skb->data, &source_addr, &dest_addr));
 			skb_pull(skb,
 				 x25_parse_facilities(skb, &x25->facilities,
-						      &x25->vc_facil_mask));
+						&x25->dte_facilities,
+						&x25->vc_facil_mask));
 			/*
 			 *	Copy any Call User Data.
 			 */

net/x25/x25_subr.c

···
 			dptr    = skb_put(skb, len);
 			memcpy(dptr, addresses, len);
 			len     = x25_create_facilities(facilities,
-							&x25->facilities,
-					     x25->neighbour->global_facil_mask);
+					&x25->facilities,
+					&x25->dte_facilities,
+					x25->neighbour->global_facil_mask);
 			dptr    = skb_put(skb, len);
 			memcpy(dptr, facilities, len);
 			dptr = skb_put(skb, x25->calluserdata.cudlength);
···
 			*dptr++ = 0x00;		/* Address lengths */
 			len     = x25_create_facilities(facilities,
 							&x25->facilities,
+							&x25->dte_facilities,
 							x25->vc_facil_mask);
 			dptr    = skb_put(skb, len);
 			memcpy(dptr, facilities, len);