if_ether.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

/*
 * Copyright (c) 1982, 1986, 1988, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)if_ether.c	8.1 (Berkeley) 6/10/93
 * $Id: if_ether.c,v 1.2 2003/01/03 18:09:25 joel Exp $
 */

/*
 * Ethernet address resolution protocol.
 * TODO:
 *	add "inuse/lock" bit (or ref. count) along with valid bit
 */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/queue.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/syslog.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <net/netisr.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/if_ether.h>

#define SIN(s) ((struct sockaddr_in *)s)
#define SDL(s) ((struct sockaddr_dl *)s)

SYSCTL_DECL(_net_link_ether);
SYSCTL_NODE(_net_link_ether, PF_INET, inet, CTLFLAG_RW, 0, "");

/* timer values */
static int arpt_prune = (5*60*1); /* walk list every 5 minutes */
static int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */
static int arpt_down = 20;	/* once declared down, don't send for 20 sec */

SYSCTL_INT(_net_link_ether_inet, OID_AUTO, prune_intvl, CTLFLAG_RW,
	   &arpt_prune, 0, "");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, 
	   &arpt_keep, 0, "");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, host_down_time, CTLFLAG_RW,
	   &arpt_down, 0, "");

#define	rt_expire rt_rmx.rmx_expire

struct llinfo_arp {
	LIST_ENTRY(llinfo_arp) la_le;
	struct	rtentry *la_rt;
	struct	mbuf *la_hold;		/* last packet until resolved/timeout */
	long	la_asked;		/* last time we QUERIED for this addr */
#define la_timer la_rt->rt_rmx.rmx_expire /* deletion time in seconds */
};

static	LIST_HEAD(, llinfo_arp) llinfo_arp;

struct	ifqueue arpintrq = {0, 0, 0, 50};
static int	arp_inuse, arp_allocated;

static int	arp_maxtries = 5;
static int	useloopback = 1; /* use loopback interface for local traffic */
static int	arp_proxyall = 0;

SYSCTL_INT(_net_link_ether_inet, OID_AUTO, maxtries, CTLFLAG_RW,
	   &arp_maxtries, 0, "");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW,
	   &useloopback, 0, "");
SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
	   &arp_proxyall, 0, "");

static void	arp_rtrequest __P((int, struct rtentry *, struct sockaddr *));
static void	arprequest __P((struct arpcom *, u_long *, u_long *, u_char *));
void	arpintr __P((void));
static void	arptfree __P((struct llinfo_arp *));
static void	arptimer __P((void *));
static struct llinfo_arp
		*arplookup __P((u_long, int, int));
static void	in_arpinput __P((struct mbuf *));

/*
 * Timeout routine.  Age arp_tab entries periodically.
 */
/* ARGSUSED */
static void
arptimer(ignored_arg)
	void *ignored_arg;
{
	int s = splnet();
	register struct llinfo_arp *la = llinfo_arp.lh_first;
	struct llinfo_arp *ola;

	timeout(arptimer, (caddr_t)0, arpt_prune * hz);
	while ((ola = la) != 0) {
		register struct rtentry *rt = la->la_rt;
		la = la->la_le.le_next;
		if (rt->rt_expire && rt->rt_expire <= rtems_bsdnet_seconds_since_boot())
			arptfree(ola); /* timer has expired, clear */
	}
	splx(s);
}

/*
 * Parallel to llc_rtrequest.
 */
static void
arp_rtrequest(req, rt, sa)
	int req;
	register struct rtentry *rt;
	struct sockaddr *sa;
{
	register struct sockaddr *gate = rt->rt_gateway;
	register struct llinfo_arp *la = (struct llinfo_arp *)rt->rt_llinfo;
	static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK};
	static int arpinit_done;

	if (!arpinit_done) {
		arpinit_done = 1;
		LIST_INIT(&llinfo_arp);
		timeout(arptimer, (caddr_t)0, hz);
	}
	if (rt->rt_flags & RTF_GATEWAY)
		return;
	switch (req) {

	case RTM_ADD:
		/*
		 * XXX: If this is a manually added route to interface
		 * such as older version of routed or gated might provide,
		 * restore cloning bit.
		 */
		if ((rt->rt_flags & RTF_HOST) == 0 &&
		    SIN(rt_mask(rt))->sin_addr.s_addr != 0xffffffff)
			rt->rt_flags |= RTF_CLONING;
		if (rt->rt_flags & RTF_CLONING) {
			/*
			 * Case 1: This route should come from a route to iface.
			 */
			rt_setgate(rt, rt_key(rt),
					(struct sockaddr *)&null_sdl);
			gate = rt->rt_gateway;
			SDL(gate)->sdl_type = rt->rt_ifp->if_type;
			SDL(gate)->sdl_index = rt->rt_ifp->if_index;
			rt->rt_expire = rtems_bsdnet_seconds_since_boot();
			break;
		}
		/* Announce a new entry if requested. */
		if (rt->rt_flags & RTF_ANNOUNCE)
			arprequest((struct arpcom *)rt->rt_ifp,
			    &SIN(rt_key(rt))->sin_addr.s_addr,
			    &SIN(rt_key(rt))->sin_addr.s_addr,
			    (u_char *)LLADDR(SDL(gate)));
		/*FALLTHROUGH*/
	case RTM_RESOLVE:
		if (gate->sa_family != AF_LINK ||
		    gate->sa_len < sizeof(null_sdl)) {
			log(LOG_DEBUG, "arp_rtrequest: bad gateway value\n");
			break;
		}
		SDL(gate)->sdl_type = rt->rt_ifp->if_type;
		SDL(gate)->sdl_index = rt->rt_ifp->if_index;
		if (la != 0)
			break; /* This happens on a route change */
		/*
		 * Case 2:  This route may come from cloning, or a manual route
		 * add with a LL address.
		 */
		R_Malloc(la, struct llinfo_arp *, sizeof(*la));
		rt->rt_llinfo = (caddr_t)la;
		if (la == 0) {
			log(LOG_DEBUG, "arp_rtrequest: malloc failed\n");
			break;
		}
		arp_inuse++, arp_allocated++;
		Bzero(la, sizeof(*la));
		la->la_rt = rt;
		rt->rt_flags |= RTF_LLINFO;
		LIST_INSERT_HEAD(&llinfo_arp, la, la_le);

		/*
		 * This keeps the multicast addresses from showing up
		 * in `arp -a' listings as unresolved.  It's not actually
		 * functional.  Then the same for broadcast.
		 */
		if (IN_MULTICAST(ntohl(SIN(rt_key(rt))->sin_addr.s_addr))) {
			ETHER_MAP_IP_MULTICAST(&SIN(rt_key(rt))->sin_addr,
					       LLADDR(SDL(gate)));
			SDL(gate)->sdl_alen = 6;
			rt->rt_expire = 0;
		}
		if (in_broadcast(SIN(rt_key(rt))->sin_addr, rt->rt_ifp)) {
			memcpy(LLADDR(SDL(gate)), etherbroadcastaddr, 6);
			SDL(gate)->sdl_alen = 6;
			rt->rt_expire = 0;
		}

		if (SIN(rt_key(rt))->sin_addr.s_addr ==
		    (IA_SIN(rt->rt_ifa))->sin_addr.s_addr) {
		    /*
		     * This test used to be
		     *	if (loif.if_flags & IFF_UP)
		     * It allowed local traffic to be forced
		     * through the hardware by configuring the loopback down.
		     * However, it causes problems during network configuration
		     * for boards that can't receive packets they send.
		     * It is now necessary to clear "useloopback" and remove
		     * the route to force traffic out to the hardware.
		     */
			rt->rt_expire = 0;
			Bcopy(((struct arpcom *)rt->rt_ifp)->ac_enaddr,
				LLADDR(SDL(gate)), SDL(gate)->sdl_alen = 6);
			if (useloopback)
				rt->rt_ifp = loif;

		}
		break;

	case RTM_DELETE:
		if (la == 0)
			break;
		arp_inuse--;
		LIST_REMOVE(la, la_le);
		rt->rt_llinfo = 0;
		rt->rt_flags &= ~RTF_LLINFO;
		if (la->la_hold)
			m_freem(la->la_hold);
		Free((caddr_t)la);
	}
}

/*
 * Broadcast an ARP request. Caller specifies:
 *	- arp header source ip address
 *	- arp header target ip address
 *	- arp header source ethernet address
 */
static void
arprequest(ac, sip, tip, enaddr)
	register struct arpcom *ac;
	register u_long *sip, *tip;
	register u_char *enaddr;
{
	register struct mbuf *m;
	register struct ether_header *eh;
	register struct ether_arp *ea;
	struct sockaddr sa;

	if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
		return;
	m->m_len = sizeof(*ea);
	m->m_pkthdr.len = sizeof(*ea);
	MH_ALIGN(m, sizeof(*ea));
	ea = mtod(m, struct ether_arp *);
	eh = (struct ether_header *)sa.sa_data;
	bzero((caddr_t)ea, sizeof (*ea));
	(void)memcpy(eh->ether_dhost, etherbroadcastaddr, sizeof(eh->ether_dhost));
	eh->ether_type = htons(ETHERTYPE_ARP);	/* if_output will not swap */
	ea->arp_hrd = htons(ARPHRD_ETHER);
	ea->arp_pro = htons(ETHERTYPE_IP);
	ea->arp_hln = sizeof(ea->arp_sha);	/* hardware address length */
	ea->arp_pln = sizeof(ea->arp_spa);	/* protocol address length */
	ea->arp_op = htons(ARPOP_REQUEST);
	(void)memcpy(ea->arp_sha, enaddr, sizeof(ea->arp_sha));
	(void)memcpy(ea->arp_spa, sip, sizeof(ea->arp_spa));
	(void)memcpy(ea->arp_tpa, tip, sizeof(ea->arp_tpa));
	sa.sa_family = AF_UNSPEC;
	sa.sa_len = sizeof(sa);
	(*ac->ac_if.if_output)(&ac->ac_if, m, &sa, (struct rtentry *)0);
}

/*
 * Resolve an IP address into an ethernet address.  If success,
 * desten is filled in.  If there is no entry in arptab,
 * set one up and broadcast a request for the IP address.
 * Hold onto this mbuf and resend it once the address
 * is finally resolved.  A return value of 1 indicates
 * that desten has been filled in and the packet should be sent
 * normally; a 0 return indicates that the packet has been
 * taken over here, either now or for later transmission.
 */
int
arpresolve(ac, rt, m, dst, desten, rt0)
	register struct arpcom *ac;
	register struct rtentry *rt;
	struct mbuf *m;
	register struct sockaddr *dst;