[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 <spereira@tusc.com.au>
Acked-by: Andrew Hendry <ahendry@tusc.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 70 insertions, 12 deletions

diff --git a/net/x25/x25_facilities.c b/net/x25/x25_facilities.c
index 54278b962f4c..9f42b9c9de37 100644
--- a/net/x25/x25_facilities.c
+++ b/net/x25/x25_facilities.c
@@ -28,18 +28,28 @@
 #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_CLASS_A:
@@ -74,6 +84,8 @@ int x25_parse_facilities(struct sk_buff *skb,
 				facilities->throughput = p[1];
 				*vc_fac_mask |= X25_MASK_THROUGHPUT;
 				break;
+			case X25_MARKER:
+				break;
 			default:
 				printk(KERN_DEBUG "X.25: unknown facility "
 				       "%02X, value %02X\n",
@@ -112,11 +124,30 @@ int x25_parse_facilities(struct sk_buff *skb,
 			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;
 		}
 	}
@@ -128,8 +159,8 @@ int x25_parse_facilities(struct sk_buff *skb,
  *	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;
@@ -168,6 +199,33 @@ int x25_create_facilities(unsigned char *buffer,
 		*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;
 
@@ -180,7 +238,7 @@ int x25_create_facilities(unsigned char *buffer,
  *	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;
@@ -190,7 +248,7 @@ int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk,
 	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.