ndisc.c

嵌入式系统设计与实验教材二源码linux内核移植与编译

/*
 *	Neighbour Discovery for IPv6
 *	Linux INET6 implementation 
 *
 *	Authors:
 *	Pedro Roque		<[e-mail]>	
 *	Mike Shaver		<[e-mail]>
 *
 *	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.
 */

/*
 *	Changes:
 *
 *	Lars Fenneberg			:	fixed MTU setting on receipt
 *						of an RA.
 *
 *	Janos Farkas			:	kmalloc failure checks
 *	Alexey Kuznetsov		:	state machine reworked
 *						and moved to net/core.
 *	Pekka Savola			:	RFC2461 validation
 */

/* Set to 3 to get tracing... */
#define ND_DEBUG 1

#define ND_PRINTK(x...) printk(KERN_DEBUG x)
#define ND_NOPRINTK(x...) do { ; } while(0)
#define ND_PRINTK0 ND_PRINTK
#define ND_PRINTK1 ND_NOPRINTK
#define ND_PRINTK2 ND_NOPRINTK
#if ND_DEBUG >= 1
#undef ND_PRINTK1
#define ND_PRINTK1 ND_PRINTK
#endif
#if ND_DEBUG >= 2
#undef ND_PRINTK2
#define ND_PRINTK2 ND_PRINTK
#endif

#define __NO_VERSION__
#include <linux/module.h>
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/sched.h>
#include <linux/net.h>
#include <linux/in6.h>
#include <linux/route.h>
#include <linux/init.h>
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif

#include <linux/if_arp.h>
#include <linux/ipv6.h>
#include <linux/icmpv6.h>

#include <net/sock.h>
#include <net/snmp.h>

#include <net/ipv6.h>
#include <net/protocol.h>
#include <net/ndisc.h>
#include <net/ip6_route.h>
#include <net/addrconf.h>
#include <net/icmp.h>

#include <net/checksum.h>
#include <linux/proc_fs.h>

static struct socket *ndisc_socket;

static u32 ndisc_hash(const void *pkey, const struct net_device *dev);
static int ndisc_constructor(struct neighbour *neigh);
static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb);
static void ndisc_error_report(struct neighbour *neigh, struct sk_buff *skb);
static int pndisc_constructor(struct pneigh_entry *n);
static void pndisc_destructor(struct pneigh_entry *n);
static void pndisc_redo(struct sk_buff *skb);

static struct neigh_ops ndisc_generic_ops =
{
	AF_INET6,
	NULL,
	ndisc_solicit,
	ndisc_error_report,
	neigh_resolve_output,
	neigh_connected_output,
	dev_queue_xmit,
	dev_queue_xmit
};

static struct neigh_ops ndisc_hh_ops =
{
	AF_INET6,
	NULL,
	ndisc_solicit,
	ndisc_error_report,
	neigh_resolve_output,
	neigh_resolve_output,
	dev_queue_xmit,
	dev_queue_xmit
};


static struct neigh_ops ndisc_direct_ops =
{
	AF_INET6,
	NULL,
	NULL,
	NULL,
	dev_queue_xmit,
	dev_queue_xmit,
	dev_queue_xmit,
	dev_queue_xmit
};

struct neigh_table nd_tbl =
{
	NULL,
	AF_INET6,
	sizeof(struct neighbour) + sizeof(struct in6_addr),
	sizeof(struct in6_addr),
	ndisc_hash,
	ndisc_constructor,
	pndisc_constructor,
	pndisc_destructor,
	pndisc_redo,
	"ndisc_cache",
        { NULL, NULL, &nd_tbl, 0, NULL, NULL,
		  30*HZ, 1*HZ, 60*HZ, 30*HZ, 5*HZ, 3, 3, 0, 3, 1*HZ, (8*HZ)/10, 64, 0 },
	30*HZ, 128, 512, 1024,
};

#define NDISC_OPT_SPACE(len) (((len)+2+7)&~7)

static u8 *ndisc_fill_option(u8 *opt, int type, void *data, int data_len)
{
	int space = NDISC_OPT_SPACE(data_len);

	opt[0] = type;
	opt[1] = space>>3;
	memcpy(opt+2, data, data_len);
	data_len += 2;
	opt += data_len;
	if ((space -= data_len) > 0)
		memset(opt, 0, space);
	return opt + space;
}

int ndisc_mc_map(struct in6_addr *addr, char *buf, struct net_device *dev, int dir)
{
	switch (dev->type) {
	case ARPHRD_ETHER:
	case ARPHRD_IEEE802:	/* Not sure. Check it later. --ANK */
	case ARPHRD_FDDI:
		ipv6_eth_mc_map(addr, buf);
		return 0;
	case ARPHRD_IEEE802_TR:
		ipv6_tr_mc_map(addr,buf);
		return 0;
	default:
		if (dir) {
			memcpy(buf, dev->broadcast, dev->addr_len);
			return 0;
		}
	}
	return -EINVAL;
}

static u32 ndisc_hash(const void *pkey, const struct net_device *dev)
{
	u32 hash_val;

	hash_val = *(u32*)(pkey + sizeof(struct in6_addr) - 4);
	hash_val ^= (hash_val>>16);
	hash_val ^= hash_val>>8;
	hash_val ^= hash_val>>3;
	hash_val = (hash_val^dev->ifindex)&NEIGH_HASHMASK;

	return hash_val;
}

static int ndisc_constructor(struct neighbour *neigh)
{
	struct in6_addr *addr = (struct in6_addr*)&neigh->primary_key;
	struct net_device *dev = neigh->dev;
	struct inet6_dev *in6_dev = in6_dev_get(dev);
	int addr_type;

	if (in6_dev == NULL)
		return -EINVAL;

	addr_type = ipv6_addr_type(addr);
	if (in6_dev->nd_parms)
		neigh->parms = in6_dev->nd_parms;

	if (addr_type&IPV6_ADDR_MULTICAST)
		neigh->type = RTN_MULTICAST;
	else
		neigh->type = RTN_UNICAST;
	if (dev->hard_header == NULL) {
		neigh->nud_state = NUD_NOARP;
		neigh->ops = &ndisc_direct_ops;
		neigh->output = neigh->ops->queue_xmit;
	} else {
		if (addr_type&IPV6_ADDR_MULTICAST) {
			neigh->nud_state = NUD_NOARP;
			ndisc_mc_map(addr, neigh->ha, dev, 1);
		} else if (dev->flags&(IFF_NOARP|IFF_LOOPBACK)) {
			neigh->nud_state = NUD_NOARP;
			memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
			if (dev->flags&IFF_LOOPBACK)
				neigh->type = RTN_LOCAL;
		} else if (dev->flags&IFF_POINTOPOINT) {
			neigh->nud_state = NUD_NOARP;
			memcpy(neigh->ha, dev->broadcast, dev->addr_len);
		}
		if (dev->hard_header_cache)
			neigh->ops = &ndisc_hh_ops;
		else
			neigh->ops = &ndisc_generic_ops;
		if (neigh->nud_state&NUD_VALID)
			neigh->output = neigh->ops->connected_output;
		else
			neigh->output = neigh->ops->output;
	}
	in6_dev_put(in6_dev);
	return 0;
}

static int pndisc_constructor(struct pneigh_entry *n)
{
	struct in6_addr *addr = (struct in6_addr*)&n->key;
	struct in6_addr maddr;
	struct net_device *dev = n->dev;

	if (dev == NULL || __in6_dev_get(dev) == NULL)
		return -EINVAL;
	addrconf_addr_solict_mult(addr, &maddr);
	ipv6_dev_mc_inc(dev, &maddr);
	return 0;
}

static void pndisc_destructor(struct pneigh_entry *n)
{
	struct in6_addr *addr = (struct in6_addr*)&n->key;
	struct in6_addr maddr;
	struct net_device *dev = n->dev;

	if (dev == NULL || __in6_dev_get(dev) == NULL)
		return;
	addrconf_addr_solict_mult(addr, &maddr);
	ipv6_dev_mc_dec(dev, &maddr);
}



static int
ndisc_build_ll_hdr(struct sk_buff *skb, struct net_device *dev,
		   struct in6_addr *daddr, struct neighbour *neigh, int len)
{
	unsigned char ha[MAX_ADDR_LEN];
	unsigned char *h_dest = NULL;

	skb_reserve(skb, (dev->hard_header_len + 15) & ~15);

	if (dev->hard_header) {
		if (ipv6_addr_type(daddr) & IPV6_ADDR_MULTICAST) {
			ndisc_mc_map(daddr, ha, dev, 1);
			h_dest = ha;
		} else if (neigh) {
			read_lock_bh(&neigh->lock);
			if (neigh->nud_state&NUD_VALID) {
				memcpy(ha, neigh->ha, dev->addr_len);
				h_dest = ha;
			}
			read_unlock_bh(&neigh->lock);
		} else {
			neigh = neigh_lookup(&nd_tbl, daddr, dev);
			if (neigh) {
				read_lock_bh(&neigh->lock);
				if (neigh->nud_state&NUD_VALID) {
					memcpy(ha, neigh->ha, dev->addr_len);
					h_dest = ha;
				}
				read_unlock_bh(&neigh->lock);
				neigh_release(neigh);
			}
		}

		if (dev->hard_header(skb, dev, ETH_P_IPV6, h_dest, NULL, len) < 0)
			return 0;
	}

	return 1;
}


/*
 *	Send a Neighbour Advertisement
 */

void ndisc_send_na(struct net_device *dev, struct neighbour *neigh,
		   struct in6_addr *daddr, struct in6_addr *solicited_addr,
		   int router, int solicited, int override, int inc_opt) 
{
        struct sock *sk = ndisc_socket->sk;
        struct nd_msg *msg;
        int len;
        struct sk_buff *skb;
	int err;

	len = sizeof(struct icmp6hdr) + sizeof(struct in6_addr);

	if (inc_opt) {
		if (dev->addr_len)
			len += NDISC_OPT_SPACE(dev->addr_len);
		else
			inc_opt = 0;
	}

	skb = sock_alloc_send_skb(sk, MAX_HEADER + len + dev->hard_header_len + 15,
				  0, &err);

	if (skb == NULL) {
		ND_PRINTK1("send_na: alloc skb failed\n");
		return;
	}

	if (ndisc_build_ll_hdr(skb, dev, daddr, neigh, len) == 0) {
		kfree_skb(skb);
		return;
	}

	ip6_nd_hdr(sk, skb, dev, solicited_addr, daddr, IPPROTO_ICMPV6, len);

	msg = (struct nd_msg *) skb_put(skb, len);

        msg->icmph.icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT;
        msg->icmph.icmp6_code = 0;
        msg->icmph.icmp6_cksum = 0;

        msg->icmph.icmp6_unused = 0;
        msg->icmph.icmp6_router    = router;
        msg->icmph.icmp6_solicited = solicited;
        msg->icmph.icmp6_override  = !!override;

        /* Set the target address. */
	ipv6_addr_copy(&msg->target, solicited_addr);

	if (inc_opt)
		ndisc_fill_option((void*)&msg->opt, ND_OPT_TARGET_LL_ADDR, dev->dev_addr, dev->addr_len);

	/* checksum */
	msg->icmph.icmp6_cksum = csum_ipv6_magic(solicited_addr, daddr, len, 
						 IPPROTO_ICMPV6,
						 csum_partial((__u8 *) msg, 
							      len, 0));

	dev_queue_xmit(skb);

	ICMP6_INC_STATS(Icmp6OutNeighborAdvertisements);
	ICMP6_INC_STATS(Icmp6OutMsgs);
}        

void ndisc_send_ns(struct net_device *dev, struct neighbour *neigh,
		   struct in6_addr *solicit,
		   struct in6_addr *daddr, struct in6_addr *saddr) 
{
        struct sock *sk = ndisc_socket->sk;
        struct sk_buff *skb;
        struct nd_msg *msg;
	struct in6_addr addr_buf;
        int len;
	int err;
	int send_llinfo;

	if (saddr == NULL) {
		if (ipv6_get_lladdr(dev, &addr_buf))
			return;
		saddr = &addr_buf;
	}

	len = sizeof(struct icmp6hdr) + sizeof(struct in6_addr);
	send_llinfo = dev->addr_len && ipv6_addr_type(saddr) != IPV6_ADDR_ANY;
	if (send_llinfo)
		len += NDISC_OPT_SPACE(dev->addr_len);

	skb = sock_alloc_send_skb(sk, MAX_HEADER + len + dev->hard_header_len + 15,
				  0, &err);
	if (skb == NULL) {
		ND_PRINTK1("send_ns: alloc skb failed\n");
		return;
	}

	if (ndisc_build_ll_hdr(skb, dev, daddr, neigh, len) == 0) {
		kfree_skb(skb);
		return;
	}

	ip6_nd_hdr(sk, skb, dev, saddr, daddr, IPPROTO_ICMPV6, len);

	msg = (struct nd_msg *)skb_put(skb, len);
	msg->icmph.icmp6_type = NDISC_NEIGHBOUR_SOLICITATION;
	msg->icmph.icmp6_code = 0;
	msg->icmph.icmp6_cksum = 0;
	msg->icmph.icmp6_unused = 0;

	/* Set the target address. */
	ipv6_addr_copy(&msg->target, solicit);

	if (send_llinfo)
		ndisc_fill_option((void*)&msg->opt, ND_OPT_SOURCE_LL_ADDR, dev->dev_addr, dev->addr_len);

	/* checksum */
	msg->icmph.icmp6_cksum = csum_ipv6_magic(&skb->nh.ipv6h->saddr,
						 daddr, len, 
						 IPPROTO_ICMPV6,
						 csum_partial((__u8 *) msg, 
							      len, 0));
	/* send it! */
	dev_queue_xmit(skb);

	ICMP6_INC_STATS(Icmp6OutNeighborSolicits);
	ICMP6_INC_STATS(Icmp6OutMsgs);
}

void ndisc_send_rs(struct net_device *dev, struct in6_addr *saddr,
		   struct in6_addr *daddr)
{
	struct sock *sk = ndisc_socket->sk;
        struct sk_buff *skb;
        struct icmp6hdr *hdr;
	__u8 * opt;
        int len;
	int err;

	len = sizeof(struct icmp6hdr);
	if (dev->addr_len)
		len += NDISC_OPT_SPACE(dev->addr_len);

        skb = sock_alloc_send_skb(sk, MAX_HEADER + len + dev->hard_header_len + 15,
				  0, &err);
	if (skb == NULL) {
		ND_PRINTK1("send_ns: alloc skb failed\n");
		return;
	}

	if (ndisc_build_ll_hdr(skb, dev, daddr, NULL, len) == 0) {
		kfree_skb(skb);
		return;
	}

	ip6_nd_hdr(sk, skb, dev, saddr, daddr, IPPROTO_ICMPV6, len);

        hdr = (struct icmp6hdr *) skb_put(skb, len);
        hdr->icmp6_type = NDISC_ROUTER_SOLICITATION;
        hdr->icmp6_code = 0;
        hdr->icmp6_cksum = 0;
        hdr->icmp6_unused = 0;

	opt = (u8*) (hdr + 1);

	if (dev->addr_len)
		ndisc_fill_option(opt, ND_OPT_SOURCE_LL_ADDR, dev->dev_addr, dev->addr_len);

	/* checksum */
	hdr->icmp6_cksum = csum_ipv6_magic(&skb->nh.ipv6h->saddr, daddr, len,
					   IPPROTO_ICMPV6,
					   csum_partial((__u8 *) hdr, len, 0));

	/* send it! */
	dev_queue_xmit(skb);

	ICMP6_INC_STATS(Icmp6OutRouterSolicits);
	ICMP6_INC_STATS(Icmp6OutMsgs);
}
		   

static u8 * ndisc_find_option(u8 *opt, int opt_len, int len, int option)
{
	while (opt_len <= len) {
		int l = opt[1]<<3;

		if (opt[0] == option && l >= opt_len)
			return opt + 2;

		if (l == 0) {
			if (net_ratelimit())
			    printk(KERN_WARNING "ndisc: option has 0 len\n");
			return NULL;
		}

		opt += l;
		len -= l;
	}
	return NULL;
}


static void ndisc_error_report(struct neighbour *neigh, struct sk_buff *skb)
{
	/*
	 *	"The sender MUST return an ICMP
	 *	 destination unreachable"
	 */
	dst_link_failure(skb);
	kfree_skb(skb);
}

/* Called with locked neigh: either read or both */

static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb)
{
	struct in6_addr *saddr = NULL;
	struct in6_addr mcaddr;
	struct net_device *dev = neigh->dev;
	struct in6_addr *target = (struct in6_addr *)&neigh->primary_key;
	int probes = atomic_read(&neigh->probes);

	if (skb && ipv6_chk_addr(&skb->nh.ipv6h->saddr, dev))
		saddr = &skb->nh.ipv6h->saddr;

	if ((probes -= neigh->parms->ucast_probes) < 0) {
		if (!(neigh->nud_state&NUD_VALID))
			ND_PRINTK1("trying to ucast probe in NUD_INVALID\n");
		ndisc_send_ns(dev, neigh, target, target, saddr);
	} else if ((probes -= neigh->parms->app_probes) < 0) {
#ifdef CONFIG_ARPD
		neigh_app_ns(neigh);
#endif
	} else {
		addrconf_addr_solict_mult(target, &mcaddr);
		ndisc_send_ns(dev, NULL, target, &mcaddr, saddr);
	}
}


static void ndisc_update(struct neighbour *neigh, u8* opt, int len, int type)
{
	opt = ndisc_find_option(opt, neigh->dev->addr_len+2, len, type);
	neigh_update(neigh, opt, NUD_STALE, 1, 1);
}

static void ndisc_router_discovery(struct sk_buff *skb)
{
        struct ra_msg *ra_msg = (struct ra_msg *) skb->h.raw;
	struct neighbour *neigh;
	struct inet6_dev *in6_dev;
	struct rt6_info *rt;
	int lifetime;
	int optlen;

	__u8 * opt = (__u8 *)(ra_msg + 1);

	optlen = (skb->tail - skb->h.raw) - sizeof(struct ra_msg);

	if (!(ipv6_addr_type(&skb->nh.ipv6h->saddr) & IPV6_ADDR_LINKLOCAL)) {
		if (net_ratelimit())
			printk(KERN_WARNING "ICMP RA: source address is not linklocal\n");
		return;
	}

	/*
	 *	set the RA_RECV flag in the interface
	 */

	in6_dev = in6_dev_get(skb->dev);
	if (in6_dev == NULL) {
		ND_PRINTK1("RA: can't find in6 device\n");
		return;
	}
	if (in6_dev->cnf.forwarding || !in6_dev->cnf.accept_ra) {
		in6_dev_put(in6_dev);
		return;
	}

	if (in6_dev->if_flags & IF_RS_SENT) {
		/*
		 *	flag that an RA was received after an RS was sent
		 *	out on this interface.
		 */
		in6_dev->if_flags |= IF_RA_RCVD;
	}

	lifetime = ntohs(ra_msg->icmph.icmp6_rt_lifetime);

	rt = rt6_get_dflt_router(&skb->nh.ipv6h->saddr, skb->dev);

	if (rt && lifetime == 0) {
		ip6_del_rt(rt);
		rt = NULL;
	}

	if (rt == NULL && lifetime) {
		ND_PRINTK2("ndisc_rdisc: adding default router\n");

		rt = rt6_add_dflt_router(&skb->nh.ipv6h->saddr, skb->dev);
		if (rt == NULL) {
			ND_PRINTK1("route_add failed\n");
			in6_dev_put(in6_dev);
			return;
		}

		neigh = rt->rt6i_nexthop;
		if (neigh == NULL) {
			ND_PRINTK1("nd: add default router: null neighbour\n");
			dst_release(&rt->u.dst);
			in6_dev_put(in6_dev);
			return;
		}
		neigh->flags |= NTF_ROUTER;

		/*
		 *	If we where using an "all destinations on link" route
		 *	delete it
		 */

		rt6_purge_dflt_routers(RTF_ALLONLINK);
	}

	if (rt)
		rt->rt6i_expires = jiffies + (HZ * lifetime);