[unix-history] / usr / src / sys / netinet / if_ether.c

/*	if_ether.c	6.9	85/04/24	*/

/*
 * Ethernet address resolution protocol.
 */

#include "param.h"
#include "systm.h"
#include "mbuf.h"
#include "socket.h"
#include "time.h"
#include "kernel.h"
#include "errno.h"
#include "ioctl.h"

#include "../net/if.h"
#include "in.h"
#include "in_systm.h"
#include "ip.h"
#include "if_ether.h"

#define	ARPTAB_BSIZ	5		/* bucket size */
#define	ARPTAB_NB	19		/* number of buckets */
#define	ARPTAB_SIZE	(ARPTAB_BSIZ * ARPTAB_NB)
struct	arptab arptab[ARPTAB_SIZE];
int	arptab_size = ARPTAB_SIZE;	/* for arp command */

#define	ARPTAB_HASH(a) \
	((short)((((a) >> 16) ^ (a)) & 0x7fff) % ARPTAB_NB)

#define	ARPTAB_LOOK(at,addr) { \
	register n; \
	at = &arptab[ARPTAB_HASH(addr) * ARPTAB_BSIZ]; \
	for (n = 0 ; n < ARPTAB_BSIZ ; n++,at++) \
		if (at->at_iaddr.s_addr == addr) \
			break; \
	if (n >= ARPTAB_BSIZ) \
		at = 0; }

int	arpt_age;		/* aging timer */

/* timer values */
#define	ARPT_AGE	(60*1)	/* aging timer, 1 min. */
#define	ARPT_KILLC	20	/* kill completed entry in 20 mins. */
#define	ARPT_KILLI	3	/* kill incomplete entry in 3 minutes */

u_char	etherbroadcastaddr[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
extern struct ifnet loif;

/*
 * Local addresses in the range oldmap to infinity are
 * mapped according to the old mapping scheme.  That is,
 * mapping of Internet to Ethernet addresses is performed
 * by taking the high three bytes of the network interface's
 * address and the low three bytes of the local address part.
 * This only allows boards from the same manufacturer to
 * communicate unless the on-board address is overridden
 * (not possible in many manufacture's hardware).
 *
 * NB: setting oldmap to zero completely disables ARP
 *     (i.e. identical to setting IFF_NOARP with an ioctl).
 */
int	oldmap = 1024;

/*
 * Timeout routine.  Age arp_tab entries once a minute.
 */
arptimer()
{
	register struct arptab *at;
	register i;

	timeout(arptimer, (caddr_t)0, hz);
	if (++arpt_age > ARPT_AGE) {
		arpt_age = 0;
		at = &arptab[0];
		for (i = 0; i < ARPTAB_SIZE; i++, at++) {
			if (at->at_flags == 0 || (at->at_flags & ATF_PERM))
				continue;
			if (++at->at_timer < ((at->at_flags&ATF_COM) ?
			    ARPT_KILLC : ARPT_KILLI))
				continue;
			/* timer has expired, clear entry */
			arptfree(at);
		}
	}
}

/*
 * Broadcast an ARP packet, asking who has addr on interface ac.
 */
arpwhohas(ac, addr)
	register struct arpcom *ac;
	struct in_addr *addr;
{
	register struct mbuf *m;
	register struct ether_header *eh;
	register struct ether_arp *ea;
	struct sockaddr sa;

	if ((m = m_get(M_DONTWAIT, MT_DATA)) == NULL)
		return (1);
	m->m_len = sizeof *ea;
	m->m_off = MMAXOFF - m->m_len;
	ea = mtod(m, struct ether_arp *);
	eh = (struct ether_header *)sa.sa_data;
	bzero((caddr_t)ea, sizeof (*ea));
	bcopy((caddr_t)etherbroadcastaddr, (caddr_t)eh->ether_dhost,
	    sizeof(eh->ether_dhost));
	eh->ether_type = ETHERTYPE_ARP;		/* if_output will 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);
	bcopy((caddr_t)ac->ac_enaddr, (caddr_t)ea->arp_sha,
	   sizeof(ea->arp_sha));
	bcopy((caddr_t)&ac->ac_ipaddr, (caddr_t)ea->arp_spa,
	   sizeof(ea->arp_spa));
	bcopy((caddr_t)addr, (caddr_t)ea->arp_tpa, sizeof(ea->arp_tpa));
	sa.sa_family = AF_UNSPEC;
	return ((*ac->ac_if.if_output)(&ac->ac_if, m, &sa));
}

/*
 * Resolve an IP address into an ethernet address.  If success, 
 * desten is filled in and 1 is returned.  If there is no entry
 * in arptab, set one up and broadcast a request 
 * for the IP address;  return 0.  Hold onto this mbuf and 
 * resend it once the address is finally resolved.
 *
 * We do some (conservative) locking here at splimp, since
 * arptab is also altered from input interrupt service (ecintr/ilintr
 * calls arpinput when ETHERTYPE_ARP packets come in).
 */
arpresolve(ac, m, destip, desten)
	register struct arpcom *ac;
	struct mbuf *m;
	register struct in_addr *destip;
	register u_char *desten;
{
	register struct arptab *at;
	register struct ifnet *ifp;
	register int i;
	struct sockaddr_in sin;
	int s, lna;

	if (in_broadcast(*destip)) {	/* broadcast address */
		bcopy((caddr_t)etherbroadcastaddr, (caddr_t)desten,
		    sizeof(etherbroadcastaddr));
		return (1);
	}
	lna = in_lnaof(*destip);
	ifp = &ac->ac_if;
	/* if for us, then use software loopback driver */
	if (destip->s_addr == ac->ac_ipaddr.s_addr &&
	    (loif.if_flags & IFF_UP)) {
		sin.sin_family = AF_INET;
		sin.sin_addr = *destip;
		(void) looutput(&loif, m, (struct sockaddr *)&sin);
		/*
		 * We really don't want to indicate failure,
		 * but the packet has already been sent and freed.
		 */
		return (0);
	}
	s = splimp();
	ARPTAB_LOOK(at, destip->s_addr);
	if (at == 0) {			/* not found */
		if ((ifp->if_flags & IFF_NOARP) || lna >= oldmap) {
			bcopy((caddr_t)ac->ac_enaddr, (caddr_t)desten, 3);
			desten[3] = (lna >> 16) & 0x7f;
			desten[4] = (lna >> 8) & 0xff;
			desten[5] = lna & 0xff;
			splx(s);
			return (1);
		} else {
			at = arptnew(destip);
			at->at_hold = m;
			arpwhohas(ac, destip);
			splx(s);
			return (0);
		}
	}
	at->at_timer = 0;		/* restart the timer */
	if (at->at_flags & ATF_COM) {	/* entry IS complete */
		bcopy((caddr_t)at->at_enaddr, (caddr_t)desten,
		    sizeof(at->at_enaddr));
		splx(s);
		return (1);
	}
	/*
	 * There is an arptab entry, but no ethernet address
	 * response yet.  Replace the held mbuf with this
	 * latest one.
	 */
	if (at->at_hold)
		m_freem(at->at_hold);
	at->at_hold = m;
	arpwhohas(ac, destip);		/* ask again */
	splx(s);
	return (0);
}

/*
 * Called from 10 Mb/s Ethernet interrupt handlers
 * when ether packet type ETHERTYPE_ARP
 * is received.  Algorithm is that given in RFC 826.
 * In addition, a sanity check is performed on the sender
 * protocol address, to catch impersonators.
 */
arpinput(ac, m)
	register struct arpcom *ac;
	struct mbuf *m;
{
	register struct ether_arp *ea;
	struct ether_header *eh;
	register struct arptab *at = 0;  /* same as "merge" flag */
	struct sockaddr_in sin;
	struct sockaddr sa;
	struct in_addr isaddr,itaddr,myaddr;

	if (m->m_len < sizeof *ea)
		goto out;
	if (ac->ac_if.if_flags & IFF_NOARP)
		goto out;
	myaddr = ac->ac_ipaddr;
	ea = mtod(m, struct ether_arp *);
	if (ntohs(ea->arp_pro) != ETHERTYPE_IP)
		goto out;
	isaddr.s_addr = ((struct in_addr *)ea->arp_spa)->s_addr;
	itaddr.s_addr = ((struct in_addr *)ea->arp_tpa)->s_addr;
	if (!bcmp((caddr_t)ea->arp_sha, (caddr_t)ac->ac_enaddr,
	  sizeof (ea->arp_sha)))
		goto out;	/* it's from me, ignore it. */
	if (isaddr.s_addr == myaddr.s_addr) {
		printf("duplicate IP address!! sent from ethernet address: ");
		printf("%x %x %x %x %x %x\n", ea->arp_sha[0], ea->arp_sha[1],
			ea->arp_sha[2], ea->arp_sha[3],
			ea->arp_sha[4], ea->arp_sha[5]);
		itaddr = myaddr;
		if (ntohs(ea->arp_op) == ARPOP_REQUEST) {
			bcopy((caddr_t)ac->ac_enaddr, (caddr_t)ea->arp_sha,
			    sizeof(ea->arp_sha));
			goto reply;
		}
		goto out;
	}
	ARPTAB_LOOK(at, isaddr.s_addr);
	if (at && (at->at_flags & ATF_COM) == 0) {
		bcopy((caddr_t)ea->arp_sha, (caddr_t)at->at_enaddr,
		    sizeof(ea->arp_sha));
		at->at_flags |= ATF_COM;
		if (at->at_hold) {
			sin.sin_family = AF_INET;
			sin.sin_addr = isaddr;
			(*ac->ac_if.if_output)(&ac->ac_if, 
			    at->at_hold, (struct sockaddr *)&sin);
			at->at_hold = 0;
		}
	}
	if (at == 0 && itaddr.s_addr == myaddr.s_addr) {
		/* ensure we have a table entry */
		at = arptnew(&isaddr);
		bcopy((caddr_t)ea->arp_sha, (caddr_t)at->at_enaddr,
		    sizeof(ea->arp_sha));
		at->at_flags |= ATF_COM;
	}
	if (ntohs(ea->arp_op) != ARPOP_REQUEST)
		goto out;
	ARPTAB_LOOK(at, itaddr.s_addr);
	if (at == NULL) {
		if (itaddr.s_addr != myaddr.s_addr)
			goto out;	/* if I am not the target */
		at = arptnew(&myaddr);
		bcopy((caddr_t)ac->ac_enaddr, (caddr_t)at->at_enaddr,
		   sizeof(at->at_enaddr));
		at->at_flags |= ATF_COM;
	} 
	if (itaddr.s_addr != myaddr.s_addr && (at->at_flags & ATF_PUBL) == 0)
		goto out;
		
reply:
	bcopy((caddr_t)ea->arp_sha, (caddr_t)ea->arp_tha,
	    sizeof(ea->arp_sha));
	bcopy((caddr_t)ea->arp_spa, (caddr_t)ea->arp_tpa,
	    sizeof(ea->arp_spa));
	if (at)		/* done above if at == 0 */
		bcopy((caddr_t)at->at_enaddr, (caddr_t)ea->arp_sha,
		    sizeof(ea->arp_sha));
	bcopy((caddr_t)&itaddr, (caddr_t)ea->arp_spa,
	    sizeof(ea->arp_spa));
	ea->arp_op = htons(ARPOP_REPLY);
	eh = (struct ether_header *)sa.sa_data;
	bcopy((caddr_t)ea->arp_tha, (caddr_t)eh->ether_dhost,
	    sizeof(eh->ether_dhost));
	eh->ether_type = ETHERTYPE_ARP;
	sa.sa_family = AF_UNSPEC;
	(*ac->ac_if.if_output)(&ac->ac_if, m, &sa);
	return;
out:
	m_freem(m);
	return;
}

/*
 * Free an arptab entry.
 */
arptfree(at)
	register struct arptab *at;
{
	int s = splimp();

	if (at->at_hold)
		m_freem(at->at_hold);
	at->at_hold = 0;
	at->at_timer = at->at_flags = 0;
	at->at_iaddr.s_addr = 0;
	splx(s);
}

/*
 * Enter a new address in arptab, pushing out the oldest entry 
 * from the bucket if there is no room.
 * This always succeeds since no bucket can be completely filled
 * with permanent entries (except from arpioctl when testing whether
 * another permanent entry will fit).
 */
struct arptab *
arptnew(addr)
	struct in_addr *addr;
{
	register n;
	int oldest = 0;
	register struct arptab *at, *ato = NULL;
	static int first = 1;

	if (first) {
		first = 0;
		timeout(arptimer, (caddr_t)0, hz);
	}
	at = &arptab[ARPTAB_HASH(addr->s_addr) * ARPTAB_BSIZ];
	for (n = 0; n < ARPTAB_BSIZ; n++,at++) {
		if (at->at_flags == 0)
			goto out;	 /* found an empty entry */
		if (at->at_flags & ATF_PERM)
			continue;
		if (at->at_timer > oldest) {
			oldest = at->at_timer;
			ato = at;
		}
	}
	if (ato == NULL)
		return (NULL);
	at = ato;
	arptfree(at);
out:
	at->at_iaddr = *addr;
	at->at_flags = ATF_INUSE;
	return (at);
}

arpioctl(cmd, data)
	int cmd;
	caddr_t data;
{
	register struct arpreq *ar = (struct arpreq *)data;
	register struct arptab *at;
	register struct sockaddr_in *sin;
	int s;

	if (ar->arp_pa.sa_family != AF_INET ||
	    ar->arp_ha.sa_family != AF_UNSPEC)
		return (EAFNOSUPPORT);
	sin = (struct sockaddr_in *)&ar->arp_pa;
	s = splimp();
	ARPTAB_LOOK(at, sin->sin_addr.s_addr);
	if (at == NULL) {		/* not found */
		if (cmd != SIOCSARP) {
			splx(s);
			return (ENXIO);
		}
		if (ifa_ifwithnet(&ar->arp_pa) == NULL) {
			splx(s);
			return (ENETUNREACH);
		}
	}
	switch (cmd) {

	case SIOCSARP:		/* set entry */
		if (at == NULL) {
			at = arptnew(&sin->sin_addr);
			if (ar->arp_flags & ATF_PERM) {
			/* never make all entries in a bucket permanent */
				register struct arptab *tat;
				
				/* try to re-allocate */
				tat = arptnew(&sin->sin_addr);
				if (tat == NULL) {
					arptfree(at);
					splx(s);
					return (EADDRNOTAVAIL);
				}
				arptfree(tat);
			}
		}
		bcopy((caddr_t)ar->arp_ha.sa_data, (caddr_t)at->at_enaddr,
		    sizeof(at->at_enaddr));
		at->at_flags = ATF_COM | ATF_INUSE |
			(ar->arp_flags & (ATF_PERM|ATF_PUBL));
		at->at_timer = 0;
		break;

	case SIOCDARP:		/* delete entry */
		arptfree(at);
		break;

	case SIOCGARP:		/* get entry */
		bcopy((caddr_t)at->at_enaddr, (caddr_t)ar->arp_ha.sa_data,
		    sizeof(at->at_enaddr));
		ar->arp_flags = at->at_flags;
		break;
	}
	splx(s);
	return (0);
}
Commit	Line	Data
36e09a72	1	/* if_ether.c 6.9 85/04/24 */
2b0e2bab SL	2
	3	/*
	4	* Ethernet address resolution protocol.
	5	*/
	6
20666ad3 JB	7	#include "param.h"
	8	#include "systm.h"
	9	#include "mbuf.h"
	10	#include "socket.h"
	11	#include "time.h"
	12	#include "kernel.h"
	13	#include "errno.h"
	14	#include "ioctl.h"
2b0e2bab SL	15
2b0e2bab SL	16	#include "../net/if.h"
20666ad3 JB	17	#include "in.h"
	18	#include "in_systm.h"
	19	#include "ip.h"
	20	#include "if_ether.h"
2b0e2bab	21
2b0e2bab SL	22	#define ARPTAB_BSIZ 5 /* bucket size */
	23	#define ARPTAB_NB 19 /* number of buckets */
	24	#define ARPTAB_SIZE (ARPTAB_BSIZ * ARPTAB_NB)
	25	struct arptab arptab[ARPTAB_SIZE];
07847ffa	26	int arptab_size = ARPTAB_SIZE; /* for arp command */
2b0e2bab SL	27
	28	#define ARPTAB_HASH(a) \
	29	((short)((((a) >> 16) ^ (a)) & 0x7fff) % ARPTAB_NB)
	30
	31	#define ARPTAB_LOOK(at,addr) { \
	32	register n; \
	33	at = &arptab[ARPTAB_HASH(addr) * ARPTAB_BSIZ]; \
	34	for (n = 0 ; n < ARPTAB_BSIZ ; n++,at++) \
	35	if (at->at_iaddr.s_addr == addr) \
	36	break; \
	37	if (n >= ARPTAB_BSIZ) \
	38	at = 0; }
	39
2b0e2bab SL	40	int arpt_age; /* aging timer */
	41
	42	/* timer values */
	43	#define ARPT_AGE (601) / aging timer, 1 min. */
	44	#define ARPT_KILLC 20 /* kill completed entry in 20 mins. */
	45	#define ARPT_KILLI 3 /* kill incomplete entry in 3 minutes */
	46
9350cacc	47	u_char etherbroadcastaddr[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
2b0e2bab SL	48	extern struct ifnet loif;
2b0e2bab SL	49
1a259c14 SL	50	/*
	51	* Local addresses in the range oldmap to infinity are
	52	* mapped according to the old mapping scheme. That is,
	53	* mapping of Internet to Ethernet addresses is performed
	54	* by taking the high three bytes of the network interface's
	55	* address and the low three bytes of the local address part.
	56	* This only allows boards from the same manufacturer to
	57	* communicate unless the on-board address is overridden
	58	* (not possible in many manufacture's hardware).
	59	*
	60	* NB: setting oldmap to zero completely disables ARP
	61	* (i.e. identical to setting IFF_NOARP with an ioctl).
	62	*/
	63	int oldmap = 1024;
2b0e2bab	64
2b0e2bab SL	65	/*
	66	* Timeout routine. Age arp_tab entries once a minute.
	67	*/
	68	arptimer()
	69	{
2b0e2bab SL	70	register struct arptab *at;
	71	register i;
	72
755d8841	73	timeout(arptimer, (caddr_t)0, hz);
2b0e2bab SL	74	if (++arpt_age > ARPT_AGE) {
	75	arpt_age = 0;
	76	at = &arptab[0];
	77	for (i = 0; i < ARPTAB_SIZE; i++, at++) {
07847ffa	78	if (at->at_flags == 0 \|\| (at->at_flags & ATF_PERM))
2b0e2bab SL	79	continue;
	80	if (++at->at_timer < ((at->at_flags&ATF_COM) ?
	81	ARPT_KILLC : ARPT_KILLI))
	82	continue;
	83	/* timer has expired, clear entry */
	84	arptfree(at);
	85	}
	86	}
	87	}
	88
	89	/*
	90	* Broadcast an ARP packet, asking who has addr on interface ac.
	91	*/
	92	arpwhohas(ac, addr)
	93	register struct arpcom *ac;
	94	struct in_addr *addr;
	95	{
	96	register struct mbuf *m;
	97	register struct ether_header *eh;
	98	register struct ether_arp *ea;
	99	struct sockaddr sa;
	100
	101	if ((m = m_get(M_DONTWAIT, MT_DATA)) == NULL)
07847ffa	102	return (1);
b5bc9bc1	103	m->m_len = sizeof *ea;
2b0e2bab SL	104	m->m_off = MMAXOFF - m->m_len;
	105	ea = mtod(m, struct ether_arp *);
	106	eh = (struct ether_header *)sa.sa_data;
755d8841	107	bzero((caddr_t)ea, sizeof (*ea));
9350cacc MK	108	bcopy((caddr_t)etherbroadcastaddr, (caddr_t)eh->ether_dhost,
9350cacc MK	109	sizeof(eh->ether_dhost));
935a6d59	110	eh->ether_type = ETHERTYPE_ARP; /* if_output will swap */
2b0e2bab	111	ea->arp_hrd = htons(ARPHRD_ETHER);
935a6d59	112	ea->arp_pro = htons(ETHERTYPE_IP);
9350cacc MK	113	ea->arp_hln = sizeof(ea->arp_sha); /* hardware address length */
9350cacc MK	114	ea->arp_pln = sizeof(ea->arp_spa); /* protocol address length */
2b0e2bab	115	ea->arp_op = htons(ARPOP_REQUEST);
9350cacc MK	116	bcopy((caddr_t)ac->ac_enaddr, (caddr_t)ea->arp_sha,
	117	sizeof(ea->arp_sha));
	118	bcopy((caddr_t)&ac->ac_ipaddr, (caddr_t)ea->arp_spa,
	119	sizeof(ea->arp_spa));
	120	bcopy((caddr_t)addr, (caddr_t)ea->arp_tpa, sizeof(ea->arp_tpa));
2b0e2bab	121	sa.sa_family = AF_UNSPEC;
07847ffa	122	return ((*ac->ac_if.if_output)(&ac->ac_if, m, &sa));
2b0e2bab SL	123	}
	124
	125	/*
	126	* Resolve an IP address into an ethernet address. If success,
	127	* desten is filled in and 1 is returned. If there is no entry
	128	* in arptab, set one up and broadcast a request
	129	* for the IP address; return 0. Hold onto this mbuf and
	130	* resend it once the address is finally resolved.
	131	*
	132	* We do some (conservative) locking here at splimp, since
	133	* arptab is also altered from input interrupt service (ecintr/ilintr
935a6d59	134	* calls arpinput when ETHERTYPE_ARP packets come in).
2b0e2bab SL	135	*/
	136	arpresolve(ac, m, destip, desten)
	137	register struct arpcom *ac;
	138	struct mbuf *m;
	139	register struct in_addr *destip;
9350cacc	140	register u_char *desten;
2b0e2bab SL	141	{
2b0e2bab SL	142	register struct arptab *at;
1a259c14	143	register struct ifnet *ifp;
07847ffa	144	register int i;
2b0e2bab SL	145	struct sockaddr_in sin;
	146	int s, lna;
	147
935a6d59	148	if (in_broadcast(destip)) { / broadcast address */
9350cacc MK	149	bcopy((caddr_t)etherbroadcastaddr, (caddr_t)desten,
9350cacc MK	150	sizeof(etherbroadcastaddr));
2b0e2bab SL	151	return (1);
2b0e2bab SL	152	}
935a6d59	153	lna = in_lnaof(*destip);
1a259c14 SL	154	ifp = &ac->ac_if;
1a259c14 SL	155	/* if for us, then use software loopback driver */
935a6d59	156	if (destip->s_addr == ac->ac_ipaddr.s_addr &&
07847ffa	157	(loif.if_flags & IFF_UP)) {
2b0e2bab SL	158	sin.sin_family = AF_INET;
2b0e2bab SL	159	sin.sin_addr = *destip;
b746b290 SL	160	(void) looutput(&loif, m, (struct sockaddr *)&sin);
	161	/*
	162	* We really don't want to indicate failure,
	163	* but the packet has already been sent and freed.
	164	*/
	165	return (0);
2b0e2bab	166	}
2b0e2bab SL	167	s = splimp();
	168	ARPTAB_LOOK(at, destip->s_addr);
	169	if (at == 0) { /* not found */
07847ffa	170	if ((ifp->if_flags & IFF_NOARP) \|\| lna >= oldmap) {
9350cacc MK	171	bcopy((caddr_t)ac->ac_enaddr, (caddr_t)desten, 3);
	172	desten[3] = (lna >> 16) & 0x7f;
	173	desten[4] = (lna >> 8) & 0xff;
	174	desten[5] = lna & 0xff;
07847ffa MK	175	splx(s);
	176	return (1);
	177	} else {
	178	at = arptnew(destip);
	179	at->at_hold = m;
	180	arpwhohas(ac, destip);
	181	splx(s);
	182	return (0);
	183	}
2b0e2bab SL	184	}
	185	at->at_timer = 0; /* restart the timer */
	186	if (at->at_flags & ATF_COM) { /* entry IS complete */
9350cacc MK	187	bcopy((caddr_t)at->at_enaddr, (caddr_t)desten,
9350cacc MK	188	sizeof(at->at_enaddr));
2b0e2bab SL	189	splx(s);
	190	return (1);
	191	}
	192	/*
	193	* There is an arptab entry, but no ethernet address
	194	* response yet. Replace the held mbuf with this
	195	* latest one.
	196	*/
	197	if (at->at_hold)
	198	m_freem(at->at_hold);
	199	at->at_hold = m;
	200	arpwhohas(ac, destip); /* ask again */
	201	splx(s);
	202	return (0);
	203	}
	204
2b0e2bab	205	/*
935a6d59 MK	206	* Called from 10 Mb/s Ethernet interrupt handlers
935a6d59 MK	207	* when ether packet type ETHERTYPE_ARP
07847ffa	208	* is received. Algorithm is that given in RFC 826.
2b0e2bab SL	209	* In addition, a sanity check is performed on the sender
	210	* protocol address, to catch impersonators.
	211	*/
	212	arpinput(ac, m)
	213	register struct arpcom *ac;
	214	struct mbuf *m;
	215	{
	216	register struct ether_arp *ea;
	217	struct ether_header *eh;
	218	register struct arptab at = 0; / same as "merge" flag */
	219	struct sockaddr_in sin;
	220	struct sockaddr sa;
2b0e2bab SL	221	struct in_addr isaddr,itaddr,myaddr;
	222
	223	if (m->m_len < sizeof *ea)
	224	goto out;
07847ffa MK	225	if (ac->ac_if.if_flags & IFF_NOARP)
07847ffa MK	226	goto out;
935a6d59	227	myaddr = ac->ac_ipaddr;
2b0e2bab	228	ea = mtod(m, struct ether_arp *);
935a6d59	229	if (ntohs(ea->arp_pro) != ETHERTYPE_IP)
2b0e2bab	230	goto out;
9350cacc MK	231	isaddr.s_addr = ((struct in_addr *)ea->arp_spa)->s_addr;
	232	itaddr.s_addr = ((struct in_addr *)ea->arp_tpa)->s_addr;
	233	if (!bcmp((caddr_t)ea->arp_sha, (caddr_t)ac->ac_enaddr,
	234	sizeof (ea->arp_sha)))
2b0e2bab SL	235	goto out; /* it's from me, ignore it. */
	236	if (isaddr.s_addr == myaddr.s_addr) {
	237	printf("duplicate IP address!! sent from ethernet address: ");
9350cacc MK	238	printf("%x %x %x %x %x %x\n", ea->arp_sha[0], ea->arp_sha[1],
	239	ea->arp_sha[2], ea->arp_sha[3],
	240	ea->arp_sha[4], ea->arp_sha[5]);
07847ffa	241	itaddr = myaddr;
9350cacc MK	242	if (ntohs(ea->arp_op) == ARPOP_REQUEST) {
	243	bcopy((caddr_t)ac->ac_enaddr, (caddr_t)ea->arp_sha,
	244	sizeof(ea->arp_sha));
2b0e2bab	245	goto reply;
9350cacc	246	}
2b0e2bab SL	247	goto out;
	248	}
	249	ARPTAB_LOOK(at, isaddr.s_addr);
36e09a72	250	if (at && (at->at_flags & ATF_COM) == 0) {
9350cacc MK	251	bcopy((caddr_t)ea->arp_sha, (caddr_t)at->at_enaddr,
9350cacc MK	252	sizeof(ea->arp_sha));
2b0e2bab SL	253	at->at_flags \|= ATF_COM;
2b0e2bab SL	254	if (at->at_hold) {
2b0e2bab SL	255	sin.sin_family = AF_INET;
	256	sin.sin_addr = isaddr;
	257	(*ac->ac_if.if_output)(&ac->ac_if,
36e09a72 MK	258	at->at_hold, (struct sockaddr *)&sin);
36e09a72 MK	259	at->at_hold = 0;
2b0e2bab	260	}
36e09a72 MK	261	}
36e09a72 MK	262	if (at == 0 && itaddr.s_addr == myaddr.s_addr) {
07847ffa	263	/* ensure we have a table entry */
2b0e2bab	264	at = arptnew(&isaddr);
9350cacc MK	265	bcopy((caddr_t)ea->arp_sha, (caddr_t)at->at_enaddr,
9350cacc MK	266	sizeof(ea->arp_sha));
2b0e2bab SL	267	at->at_flags \|= ATF_COM;
	268	}
	269	if (ntohs(ea->arp_op) != ARPOP_REQUEST)
	270	goto out;
07847ffa MK	271	ARPTAB_LOOK(at, itaddr.s_addr);
	272	if (at == NULL) {
	273	if (itaddr.s_addr != myaddr.s_addr)
	274	goto out; /* if I am not the target */
	275	at = arptnew(&myaddr);
9350cacc MK	276	bcopy((caddr_t)ac->ac_enaddr, (caddr_t)at->at_enaddr,
9350cacc MK	277	sizeof(at->at_enaddr));
07847ffa MK	278	at->at_flags \|= ATF_COM;
	279	}
	280	if (itaddr.s_addr != myaddr.s_addr && (at->at_flags & ATF_PUBL) == 0)
	281	goto out;
	282
2b0e2bab	283	reply:
9350cacc MK	284	bcopy((caddr_t)ea->arp_sha, (caddr_t)ea->arp_tha,
	285	sizeof(ea->arp_sha));
	286	bcopy((caddr_t)ea->arp_spa, (caddr_t)ea->arp_tpa,
	287	sizeof(ea->arp_spa));
36e09a72 MK	288	if (at) /* done above if at == 0 */
	289	bcopy((caddr_t)at->at_enaddr, (caddr_t)ea->arp_sha,
	290	sizeof(ea->arp_sha));
9350cacc MK	291	bcopy((caddr_t)&itaddr, (caddr_t)ea->arp_spa,
9350cacc MK	292	sizeof(ea->arp_spa));
2b0e2bab SL	293	ea->arp_op = htons(ARPOP_REPLY);
2b0e2bab SL	294	eh = (struct ether_header *)sa.sa_data;
9350cacc MK	295	bcopy((caddr_t)ea->arp_tha, (caddr_t)eh->ether_dhost,
9350cacc MK	296	sizeof(eh->ether_dhost));
935a6d59	297	eh->ether_type = ETHERTYPE_ARP;
2b0e2bab SL	298	sa.sa_family = AF_UNSPEC;
	299	(*ac->ac_if.if_output)(&ac->ac_if, m, &sa);
	300	return;
	301	out:
	302	m_freem(m);
	303	return;
	304	}
	305
	306	/*
	307	* Free an arptab entry.
	308	*/
	309	arptfree(at)
	310	register struct arptab *at;
	311	{
	312	int s = splimp();
	313
	314	if (at->at_hold)
	315	m_freem(at->at_hold);
	316	at->at_hold = 0;
	317	at->at_timer = at->at_flags = 0;
	318	at->at_iaddr.s_addr = 0;
	319	splx(s);
	320	}
	321
	322	/*
	323	* Enter a new address in arptab, pushing out the oldest entry
	324	* from the bucket if there is no room.
07847ffa MK	325	* This always succeeds since no bucket can be completely filled
07847ffa MK	326	* with permanent entries (except from arpioctl when testing whether
9350cacc	327	* another permanent entry will fit).
2b0e2bab SL	328	*/
	329	struct arptab *
	330	arptnew(addr)
	331	struct in_addr *addr;
	332	{
	333	register n;
	334	int oldest = 0;
07847ffa MK	335	register struct arptab at, ato = NULL;
07847ffa MK	336	static int first = 1;
2b0e2bab	337
07847ffa MK	338	if (first) {
	339	first = 0;
	340	timeout(arptimer, (caddr_t)0, hz);
	341	}
	342	at = &arptab[ARPTAB_HASH(addr->s_addr) * ARPTAB_BSIZ];
9350cacc	343	for (n = 0; n < ARPTAB_BSIZ; n++,at++) {
2b0e2bab SL	344	if (at->at_flags == 0)
2b0e2bab SL	345	goto out; /* found an empty entry */
07847ffa MK	346	if (at->at_flags & ATF_PERM)
07847ffa MK	347	continue;
2b0e2bab SL	348	if (at->at_timer > oldest) {
	349	oldest = at->at_timer;
	350	ato = at;
	351	}
	352	}
07847ffa	353	if (ato == NULL)
9350cacc	354	return (NULL);
2b0e2bab SL	355	at = ato;
	356	arptfree(at);
	357	out:
	358	at->at_iaddr = *addr;
	359	at->at_flags = ATF_INUSE;
	360	return (at);
	361	}
07847ffa MK	362
	363	arpioctl(cmd, data)
	364	int cmd;
	365	caddr_t data;
	366	{
	367	register struct arpreq ar = (struct arpreq )data;
	368	register struct arptab *at;
	369	register struct sockaddr_in *sin;
	370	int s;
	371
	372	if (ar->arp_pa.sa_family != AF_INET \|\|
	373	ar->arp_ha.sa_family != AF_UNSPEC)
	374	return (EAFNOSUPPORT);
	375	sin = (struct sockaddr_in *)&ar->arp_pa;
	376	s = splimp();
	377	ARPTAB_LOOK(at, sin->sin_addr.s_addr);
	378	if (at == NULL) { /* not found */
	379	if (cmd != SIOCSARP) {
	380	splx(s);
	381	return (ENXIO);
	382	}
935a6d59	383	if (ifa_ifwithnet(&ar->arp_pa) == NULL) {
07847ffa MK	384	splx(s);
	385	return (ENETUNREACH);
	386	}
	387	}
	388	switch (cmd) {
	389
	390	case SIOCSARP: /* set entry */
	391	if (at == NULL) {
	392	at = arptnew(&sin->sin_addr);
	393	if (ar->arp_flags & ATF_PERM) {
	394	/* never make all entries in a bucket permanent */
	395	register struct arptab *tat;
	396
	397	/* try to re-allocate */
	398	tat = arptnew(&sin->sin_addr);
	399	if (tat == NULL) {
	400	arptfree(at);
	401	splx(s);
	402	return (EADDRNOTAVAIL);
	403	}
	404	arptfree(tat);
	405	}
	406	}
9350cacc MK	407	bcopy((caddr_t)ar->arp_ha.sa_data, (caddr_t)at->at_enaddr,
9350cacc MK	408	sizeof(at->at_enaddr));
07847ffa MK	409	at->at_flags = ATF_COM \| ATF_INUSE \|
	410	(ar->arp_flags & (ATF_PERM\|ATF_PUBL));
	411	at->at_timer = 0;
	412	break;
	413
	414	case SIOCDARP: /* delete entry */
	415	arptfree(at);
	416	break;
	417
	418	case SIOCGARP: /* get entry */
9350cacc MK	419	bcopy((caddr_t)at->at_enaddr, (caddr_t)ar->arp_ha.sa_data,
9350cacc MK	420	sizeof(at->at_enaddr));
07847ffa MK	421	ar->arp_flags = at->at_flags;
	422	break;
	423	}
	424	splx(s);
	425	return (0);
	426	}