patch-2.1.15 linux/drivers/net/tunnel.c

• Lines: 314
• Date: Thu Dec 12 16:51:10 1996
• Orig file: v2.1.14/linux/drivers/net/tunnel.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v2.1.14/linux/drivers/net/tunnel.c linux/drivers/net/tunnel.c
@@ -0,0 +1,313 @@
+/* tunnel.c: an IP tunnel driver
+
+	The purpose of this driver is to provide an IP tunnel through
+	which you can tunnel network traffic transparently across subnets.
+
+	This was written by looking at Nick Holloway's dummy driver
+	Thanks for the great code!
+
+		-Sam Lantinga	(slouken@cs.ucdavis.edu)  02/01/95
+		
+	Minor tweaks:
+		Cleaned up the code a little and added some pre-1.3.0 tweaks.
+		dev->hard_header/hard_header_len changed to use no headers.
+		Comments/bracketing tweaked.
+		Made the tunnels use dev->name not tunnel: when error reporting.
+		Added tx_dropped stat
+		
+		-Alan Cox	(Alan.Cox@linux.org) 21 March 95
+
+	Reworked:
+		Changed to tunnel to destination gateway in addition to the
+			tunnel's pointopoint address
+		Almost completely rewritten
+		Note:  There is currently no firewall or ICMP handling done.
+
+		-Sam Lantinga	(slouken@cs.ucdavis.edu) 02/13/96
+		
+*/
+
+/* Things I wish I had known when writing the tunnel driver:
+
+	When the tunnel_xmit() function is called, the skb contains the
+	packet to be sent (plus a great deal of extra info), and dev
+	contains the tunnel device that _we_ are.
+
+	When we are passed a packet, we are expected to fill in the
+	source address with our source IP address.
+
+	What is the proper way to allocate, copy and free a buffer?
+	After you allocate it, it is a "0 length" chunk of memory
+	starting at zero.  If you want to add headers to the buffer
+	later, you'll have to call "skb_reserve(skb, amount)" with
+	the amount of memory you want reserved.  Then, you call
+	"skb_put(skb, amount)" with the amount of space you want in
+	the buffer.  skb_put() returns a pointer to the top (#0) of
+	that buffer.  skb->len is set to the amount of space you have
+	"allocated" with skb_put().  You can then write up to skb->len
+	bytes to that buffer.  If you need more, you can call skb_put()
+	again with the additional amount of space you need.  You can
+	find out how much more space you can allocate by calling 
+	"skb_tailroom(skb)".
+	Now, to add header space, call "skb_push(skb, header_len)".
+	This creates space at the beginning of the buffer and returns
+	a pointer to this new space.  If later you need to strip a
+	header from a buffer, call "skb_pull(skb, header_len)".
+	skb_headroom() will return how much space is left at the top
+	of the buffer (before the main data).  Remember, this headroom
+	space must be reserved before the skb_put() function is called.
+*/
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <net/ip.h>
+#include <linux/if_arp.h>
+
+/*#define TUNNEL_DEBUG*/
+
+/* 
+ *	Our header is a simple IP packet with no options
+ */
+ 
+#define tunnel_hlen	sizeof(struct iphdr)
+
+/*
+ *	Okay, this needs to be high enough that we can fit a "standard"
+ *	ethernet header and an IP tunnel header into the outgoing packet.
+ *	[36 bytes]
+ */
+ 
+#define TUNL_HLEN	(((ETH_HLEN+15)&~15)+tunnel_hlen)
+
+
+static int tunnel_open(struct device *dev)
+{
+	MOD_INC_USE_COUNT;
+	return 0;
+}
+
+static int tunnel_close(struct device *dev)
+{
+	MOD_DEC_USE_COUNT;
+	return 0;
+}
+
+#ifdef TUNNEL_DEBUG
+void print_ip(struct iphdr *ip)
+{
+	unsigned char *ipaddr;
+
+	printk("IP packet:\n");
+	printk("--- header len = %d\n", ip->ihl*4);
+	printk("--- ip version: %d\n", ip->version);
+	printk("--- ip protocol: %d\n", ip->protocol);
+	ipaddr=(unsigned char *)&ip->saddr;
+	printk("--- source address: %u.%u.%u.%u\n", 
+			*ipaddr, *(ipaddr+1), *(ipaddr+2), *(ipaddr+3));
+	ipaddr=(unsigned char *)&ip->daddr;
+	printk("--- destination address: %u.%u.%u.%u\n", 
+			*ipaddr, *(ipaddr+1), *(ipaddr+2), *(ipaddr+3));
+	printk("--- total packet len: %d\n", ntohs(ip->tot_len));
+}
+#endif
+
+/*
+ *	This function assumes it is being called from dev_queue_xmit()
+ *	and that skb is filled properly by that function.
+ */
+
+static int tunnel_xmit(struct sk_buff *skb, struct device *dev)
+{
+	struct enet_statistics *stats;		/* This device's statistics */
+	struct rtable *rt;     			/* Route to the other host */
+	struct hh_cache *hh;
+	struct device *tdev;			/* Device to other host */
+	struct iphdr  *iph;			/* Our new IP header */
+	int    max_headroom;			/* The extra header space needed */
+
+	stats = (struct enet_statistics *)dev->priv;
+  
+	/*
+	 *  First things first.  Look up the destination address in the 
+	 *  routing tables
+	 */
+	iph = skb->nh.iph;
+
+	if (ip_route_output(&rt, dev->pa_dstaddr, dev->pa_addr, RT_TOS(iph->tos), NULL)) {
+		/* No route to host */
+		printk ( KERN_INFO "%s: Can't reach target gateway!\n", dev->name);
+		stats->tx_errors++;
+		dev_kfree_skb(skb, FREE_WRITE);
+		return 0;
+	}
+	tdev = rt->u.dst.dev;
+	hh = rt->u.dst.hh;
+
+	if (tdev->type == ARPHRD_TUNNEL) { 
+		/* Tunnel to tunnel?  -- I don't think so. */
+		printk ( KERN_INFO "%s: Packet targetted at myself!\n" , dev->name);
+		ip_rt_put(rt);
+		stats->tx_errors++;
+		dev_kfree_skb(skb, FREE_WRITE);
+		return 0;
+	}
+
+	skb->h.ipiph = skb->nh.iph;
+
+	/*
+	 * Okay, now see if we can stuff it in the buffer as-is.
+	 */
+	max_headroom = (((tdev->hard_header_len+15)&~15)+tunnel_hlen);
+
+	if (skb_headroom(skb) < max_headroom || skb->users != 1) {
+		struct sk_buff *new_skb = skb_realloc_headroom(skb, max_headroom);
+		if (!new_skb) {
+			ip_rt_put(rt);
+  			stats->tx_dropped++;
+			dev_kfree_skb(skb, FREE_WRITE);
+			return 0;
+		}
+		dev_kfree_skb(skb, FREE_WRITE);
+		skb = new_skb;
+	}
+
+	skb->nh.iph = (struct iphdr *) skb_push(skb, tunnel_hlen);
+	dst_release(skb->dst);
+	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
+	dst_release(skb->dst);
+	skb->dst = &rt->u.dst;
+
+	/*
+	 *	Push down and install the IPIP header.
+	 */
+	 
+	iph 			=	skb->nh.iph;
+	iph->version		= 	4;
+	iph->tos		=	skb->h.ipiph->tos;
+	iph->ttl		=	skb->h.ipiph->ttl;
+	iph->frag_off		=	0;
+	iph->daddr		=	dev->pa_dstaddr;
+	iph->saddr		=	dev->pa_addr;
+	iph->protocol		=	IPPROTO_IPIP;
+	iph->ihl		=	5;
+	iph->tot_len		=	htons(skb->len);
+	iph->id			=	htons(ip_id_count++);	/* Race condition here? */
+	ip_send_check(iph);
+
+	ip_send(skb);
+
+	/* Record statistics and return */
+	stats->tx_packets++;
+	return 0;
+}
+
+static struct enet_statistics *tunnel_get_stats(struct device *dev)
+{
+	return((struct enet_statistics*) dev->priv);
+}
+
+/*
+ *	Called when a new tunnel device is initialized.
+ *	The new tunnel device structure is passed to us.
+ */
+ 
+int tunnel_init(struct device *dev)
+{
+	int i;
+
+	/* Oh, just say we're here, in case anyone cares */
+	static int tun_msg=0;
+	if(!tun_msg)
+	{
+		printk ( KERN_INFO "tunnel: version v0.2b2\n" );
+		tun_msg=1;
+	}
+
+	/* Add our tunnel functions to the device */
+	dev->open		= tunnel_open;
+	dev->stop		= tunnel_close;
+	dev->hard_start_xmit	= tunnel_xmit;
+	dev->get_stats		= tunnel_get_stats;
+	dev->priv = kmalloc(sizeof(struct enet_statistics), GFP_KERNEL);
+	if (dev->priv == NULL)
+		return -ENOMEM;
+	memset(dev->priv, 0, sizeof(struct enet_statistics));
+
+	/* Initialize the tunnel device structure */
+	for (i = 0; i < DEV_NUMBUFFS; i++)
+		skb_queue_head_init(&dev->buffs[i]);
+
+	dev->hard_header	= NULL;
+	dev->rebuild_header 	= NULL;
+	dev->set_mac_address 	= NULL;
+	dev->hard_header_cache 	= NULL;
+	dev->header_cache_update= NULL;
+
+	dev->type				= ARPHRD_TUNNEL;
+	dev->hard_header_len 	= TUNL_HLEN;
+	dev->mtu		= 1500-tunnel_hlen; 	/* eth_mtu */
+	dev->addr_len		= 0;		/* Is this only for ARP? */
+	dev->tx_queue_len	= 2;		/* Small queue */
+	memset(dev->broadcast,0xFF, ETH_ALEN);
+
+	/* New-style flags. */
+	dev->flags		= IFF_NOARP;	/* Don't use ARP on this device */
+						/* No broadcasting through a tunnel */
+	dev->family		= AF_INET;
+	dev->pa_addr		= 0;
+	dev->pa_brdaddr 	= 0;
+	dev->pa_mask		= 0;
+	dev->pa_alen		= 4;
+
+	/* We're done.  Have I forgotten anything? */
+	return 0;
+}
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+/*  Module specific interface                                      */
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+#ifdef MODULE
+
+static int tunnel_probe(struct device *dev)
+{
+	tunnel_init(dev);
+	return 0;
+}
+
+static struct device dev_tunnel = 
+{
+	"tunl0\0   ", 
+	0, 0, 0, 0,
+ 	0x0, 0,
+ 	0, 0, 0, NULL, tunnel_probe 
+ };
+
+int init_module(void)
+{
+	/* Find a name for this unit */
+	int ct= 1;
+	
+	while(dev_get(dev_tunnel.name)!=NULL && ct<100)
+	{
+		sprintf(dev_tunnel.name,"tunl%d",ct);
+		ct++;
+	}
+	
+#ifdef TUNNEL_DEBUG
+	printk("tunnel: registering device %s\n", dev_tunnel.name);
+#endif
+	if (register_netdev(&dev_tunnel) != 0)
+		return -EIO;
+	return 0;
+}
+
+void cleanup_module(void)
+{
+	unregister_netdev(&dev_tunnel);
+	kfree_s(dev_tunnel.priv,sizeof(struct enet_statistics));
+	dev_tunnel.priv=NULL;
+}
+#endif /* MODULE */
+