Initial import

1 files changed, 167 insertions, 0 deletions

diff --git a/net/802/psnap.c b/net/802/psnap.c
new file mode 100644
index 000000000..db6baf7cf
--- /dev/null
+++ b/net/802/psnap.c
@@ -0,0 +1,167 @@
+/*
+ *	SNAP data link layer. Derived from 802.2
+ *
+ *		Alan Cox <alan@lxorguk.ukuu.org.uk>,
+ *		from the 802.2 layer by Greg Page.
+ *		Merged in additions from Greg Page's psnap.c.
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <net/datalink.h>
+#include <net/llc.h>
+#include <net/psnap.h>
+#include <linux/mm.h>
+#include <linux/in.h>
+#include <linux/init.h>
+#include <linux/rculist.h>
+
+static LIST_HEAD(snap_list);
+static DEFINE_SPINLOCK(snap_lock);
+static struct llc_sap *snap_sap;
+
+/*
+ *	Find a snap client by matching the 5 bytes.
+ */
+static struct datalink_proto *find_snap_client(const unsigned char *desc)
+{
+	struct datalink_proto *proto = NULL, *p;
+
+	list_for_each_entry_rcu(p, &snap_list, node) {
+		if (!memcmp(p->type, desc, 5)) {
+			proto = p;
+			break;
+		}
+	}
+	return proto;
+}
+
+/*
+ *	A SNAP packet has arrived
+ */
+static int snap_rcv(struct sk_buff *skb, struct net_device *dev,
+		    struct packet_type *pt, struct net_device *orig_dev)
+{
+	int rc = 1;
+	struct datalink_proto *proto;
+	static struct packet_type snap_packet_type = {
+		.type = cpu_to_be16(ETH_P_SNAP),
+	};
+
+	if (unlikely(!pskb_may_pull(skb, 5)))
+		goto drop;
+
+	rcu_read_lock();
+	proto = find_snap_client(skb_transport_header(skb));
+	if (proto) {
+		/* Pass the frame on. */
+		skb->transport_header += 5;
+		skb_pull_rcsum(skb, 5);
+		rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev);
+	}
+	rcu_read_unlock();
+
+	if (unlikely(!proto))
+		goto drop;
+
+out:
+	return rc;
+
+drop:
+	kfree_skb(skb);
+	goto out;
+}
+
+/*
+ *	Put a SNAP header on a frame and pass to 802.2
+ */
+static int snap_request(struct datalink_proto *dl,
+			struct sk_buff *skb, u8 *dest)
+{
+	memcpy(skb_push(skb, 5), dl->type, 5);
+	llc_build_and_send_ui_pkt(snap_sap, skb, dest, snap_sap->laddr.lsap);
+	return 0;
+}
+
+/*
+ *	Set up the SNAP layer
+ */
+EXPORT_SYMBOL(register_snap_client);
+EXPORT_SYMBOL(unregister_snap_client);
+
+static const char snap_err_msg[] __initconst =
+	KERN_CRIT "SNAP - unable to register with 802.2\n";
+
+static int __init snap_init(void)
+{
+	snap_sap = llc_sap_open(0xAA, snap_rcv);
+	if (!snap_sap) {
+		printk(snap_err_msg);
+		return -EBUSY;
+	}
+
+	return 0;
+}
+
+module_init(snap_init);
+
+static void __exit snap_exit(void)
+{
+	llc_sap_put(snap_sap);
+}
+
+module_exit(snap_exit);
+
+
+/*
+ *	Register SNAP clients. We don't yet use this for IP.
+ */
+struct datalink_proto *register_snap_client(const unsigned char *desc,
+					    int (*rcvfunc)(struct sk_buff *,
+							   struct net_device *,
+							   struct packet_type *,
+							   struct net_device *))
+{
+	struct datalink_proto *proto = NULL;
+
+	spin_lock_bh(&snap_lock);
+
+	if (find_snap_client(desc))
+		goto out;
+
+	proto = kmalloc(sizeof(*proto), GFP_ATOMIC);
+	if (proto) {
+		memcpy(proto->type, desc, 5);
+		proto->rcvfunc		= rcvfunc;
+		proto->header_length	= 5 + 3; /* snap + 802.2 */
+		proto->request		= snap_request;
+		list_add_rcu(&proto->node, &snap_list);
+	}
+out:
+	spin_unlock_bh(&snap_lock);
+
+	return proto;
+}
+
+/*
+ *	Unregister SNAP clients. Protocols no longer want to play with us ...
+ */
+void unregister_snap_client(struct datalink_proto *proto)
+{
+	spin_lock_bh(&snap_lock);
+	list_del_rcu(&proto->node);
+	spin_unlock_bh(&snap_lock);
+
+	synchronize_net();
+
+	kfree(proto);
+}
+
+MODULE_LICENSE("GPL");