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if_arp.c
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if_arp.c
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/* $NetBSD: if_arp.c,v 1.94 2003/09/24 06:52:47 itojun Exp $ */
/*-
* Copyright (c) 1998, 2000 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Public Access Networks Corporation ("Panix"). It was developed under
* contract to Panix by Eric Haszlakiewicz and Thor Lancelot Simon.
*
* 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 NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* 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. 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 8.2 (Berkeley) 9/26/94
*/
/*
* Ethernet address resolution protocol.
* TODO:
* add "inuse/lock" bit (or ref. count) along with valid bit
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.94 2003/09/24 06:52:47 itojun Exp $");
#include "opt_ddb.h"
#include "opt_inet.h"
#ifdef INET
#include "bridge.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/callout.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/errno.h>
#include <sys/ioctl.h>
#include <sys/syslog.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/domain.h>
#include <net/ethertypes.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_token.h>
#include <net/if_types.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/if_inarp.h>
#include "loop.h"
#include "arc.h"
#if NARC > 0
#include <net/if_arc.h>
#endif
#include "fddi.h"
#if NFDDI > 0
#include <net/if_fddi.h>
#endif
#include "token.h"
#define SIN(s) ((struct sockaddr_in *)s)
#define SDL(s) ((struct sockaddr_dl *)s)
#define SRP(s) ((struct sockaddr_inarp *)s)
/*
* ARP trailer negotiation. Trailer protocol is not IP specific,
* but ARP request/response use IP addresses.
*/
#define ETHERTYPE_IPTRAILERS ETHERTYPE_TRAIL
/* timer values */
int arpt_prune = (5*60*1); /* walk list every 5 minutes */
int arpt_keep = (20*60); /* once resolved, good for 20 more minutes */
int arpt_down = 20; /* once declared down, don't send for 20 secs */
#define rt_expire rt_rmx.rmx_expire
extern struct domain arpdomain;
static void arprequest __P((struct ifnet *,
struct in_addr *, struct in_addr *, u_int8_t *));
static void arptfree __P((struct llinfo_arp *));
static void arptimer __P((void *));
static struct llinfo_arp *arplookup __P((struct mbuf *, struct in_addr *,
int, int));
static void in_arpinput __P((struct mbuf *));
#if NLOOP > 0
extern struct ifnet loif[NLOOP];
#endif
LIST_HEAD(, llinfo_arp) llinfo_arp;
struct ifqueue arpintrq = {0, 0, 0, 50};
int arp_inuse, arp_allocated, arp_intimer;
int arp_maxtries = 5;
int useloopback = 1; /* use loopback interface for local traffic */
int arpinit_done = 0;
struct arpstat arpstat;
struct callout arptimer_ch;
/* revarp state */
static struct in_addr myip, srv_ip;
static int myip_initialized = 0;
static int revarp_in_progress = 0;
static struct ifnet *myip_ifp = NULL;
#ifdef DDB
static void db_print_sa __P((struct sockaddr *));
static void db_print_ifa __P((struct ifaddr *));
static void db_print_llinfo __P((caddr_t));
static int db_show_radix_node __P((struct radix_node *, void *));
#endif
/*
* this should be elsewhere.
*/
static char *
lla_snprintf __P((u_int8_t *, int));
static char *
lla_snprintf(adrp, len)
u_int8_t *adrp;
int len;
{
#define NUMBUFS 3
static char buf[NUMBUFS][16*3];
static int bnum = 0;
static const char hexdigits[] = {
'0','1','2','3','4','5','6','7',
'8','9','a','b','c','d','e','f'
};
int i;
char *p;
p = buf[bnum];
*p++ = hexdigits[(*adrp)>>4];
*p++ = hexdigits[(*adrp++)&0xf];
for (i=1; i<len && i<16; i++) {
*p++ = ':';
*p++ = hexdigits[(*adrp)>>4];
*p++ = hexdigits[(*adrp++)&0xf];
}
*p = 0;
p = buf[bnum];
bnum = (bnum + 1) % NUMBUFS;
return p;
}
struct protosw arpsw[] = {
{ 0, 0, 0, 0,
0, 0, 0, 0,
0,
0, 0, 0, arp_drain,
}
};
struct domain arpdomain =
{ PF_ARP, "arp", 0, 0, 0,
arpsw, &arpsw[sizeof(arpsw)/sizeof(arpsw[0])]
};
/*
* ARP table locking.
*
* to prevent lossage vs. the arp_drain routine (which may be called at
* any time, including in a device driver context), we do two things:
*
* 1) manipulation of la->la_hold is done at splnet() (for all of
* about two instructions).
*
* 2) manipulation of the arp table's linked list is done under the
* protection of the ARP_LOCK; if arp_drain() or arptimer is called
* while the arp table is locked, we punt and try again later.
*/
static int arp_locked;
static __inline int arp_lock_try __P((int));
static __inline void arp_unlock __P((void));
static __inline int
arp_lock_try(int recurse)
{
int s;
/*
* Use splvm() -- we're blocking things that would cause
* mbuf allocation.
*/
s = splvm();
if (!recurse && arp_locked) {
splx(s);
return (0);
}
arp_locked++;
splx(s);
return (1);
}
static __inline void
arp_unlock()
{
int s;
s = splvm();
arp_locked--;
splx(s);
}
#ifdef DIAGNOSTIC
#define ARP_LOCK(recurse) \
do { \
if (arp_lock_try(recurse) == 0) { \
printf("%s:%d: arp already locked\n", __FILE__, __LINE__); \
panic("arp_lock"); \
} \
} while (/*CONSTCOND*/ 0)
#define ARP_LOCK_CHECK() \
do { \
if (arp_locked == 0) { \
printf("%s:%d: arp lock not held\n", __FILE__, __LINE__); \
panic("arp lock check"); \
} \
} while (/*CONSTCOND*/ 0)
#else
#define ARP_LOCK(x) (void) arp_lock_try(x)
#define ARP_LOCK_CHECK() /* nothing */
#endif
#define ARP_UNLOCK() arp_unlock()
/*
* ARP protocol drain routine. Called when memory is in short supply.
* Called at splvm();
*/
void
arp_drain()
{
struct llinfo_arp *la, *nla;
int count = 0;
struct mbuf *mold;
if (arp_lock_try(0) == 0) {
printf("arp_drain: locked; punting\n");
return;
}
for (la = LIST_FIRST(&llinfo_arp); la != 0; la = nla) {
nla = LIST_NEXT(la, la_list);
mold = la->la_hold;
la->la_hold = 0;
if (mold) {
m_freem(mold);
count++;
}
}
ARP_UNLOCK();
arpstat.as_dfrdropped += count;
}
/*
* Timeout routine. Age arp_tab entries periodically.
*/
/* ARGSUSED */
static void
arptimer(arg)
void *arg;
{
int s;
struct llinfo_arp *la, *nla;
s = splsoftnet();
if (arp_lock_try(0) == 0) {
/* get it later.. */
splx(s);
return;
}
callout_reset(&arptimer_ch, arpt_prune * hz, arptimer, NULL);
for (la = LIST_FIRST(&llinfo_arp); la != 0; la = nla) {
struct rtentry *rt = la->la_rt;
nla = LIST_NEXT(la, la_list);
if (rt->rt_expire && rt->rt_expire <= time.tv_sec)
arptfree(la); /* timer has expired; clear */
}
ARP_UNLOCK();
splx(s);
}
/*
* Parallel to llc_rtrequest.
*/
void
arp_rtrequest(req, rt, info)
int req;
struct rtentry *rt;
struct rt_addrinfo *info;
{
struct sockaddr *gate = rt->rt_gateway;
struct llinfo_arp *la = (struct llinfo_arp *)rt->rt_llinfo;
static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK};
size_t allocsize;
struct mbuf *mold;
int s;
struct in_ifaddr *ia;
struct ifaddr *ifa;
if (!arpinit_done) {
arpinit_done = 1;
/*
* We generate expiration times from time.tv_sec
* so avoid accidently creating permanent routes.
*/
if (time.tv_sec == 0) {
time.tv_sec++;
}
callout_init(&arptimer_ch);
callout_reset(&arptimer_ch, hz, arptimer, NULL);
}
if ((rt->rt_flags & RTF_GATEWAY) != 0) {
if (req != RTM_ADD)
return;
/*
* linklayers with particular link MTU limitation.
*/
switch(rt->rt_ifp->if_type) {
#if NFDDI > 0
case IFT_FDDI:
if (rt->rt_ifp->if_mtu > FDDIIPMTU)
rt->rt_rmx.rmx_mtu = FDDIIPMTU;
break;
#endif
#if NARC > 0
case IFT_ARCNET:
{
int arcipifmtu;
if (rt->rt_ifp->if_flags & IFF_LINK0)
arcipifmtu = arc_ipmtu;
else
arcipifmtu = ARCMTU;
if (rt->rt_ifp->if_mtu > arcipifmtu)
rt->rt_rmx.rmx_mtu = arcipifmtu;
break;
}
#endif
}
return;
}
ARP_LOCK(1); /* we may already be locked here. */
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;
/*
* Give this route an expiration time, even though
* it's a "permanent" route, so that routes cloned
* from it do not need their expiration time set.
*/
rt->rt_expire = time.tv_sec;
/*
* linklayers with particular link MTU limitation.
*/
switch (rt->rt_ifp->if_type) {
#if NFDDI > 0
case IFT_FDDI:
if ((rt->rt_rmx.rmx_locks & RTV_MTU) == 0 &&
(rt->rt_rmx.rmx_mtu > FDDIIPMTU ||
(rt->rt_rmx.rmx_mtu == 0 &&
rt->rt_ifp->if_mtu > FDDIIPMTU)))
rt->rt_rmx.rmx_mtu = FDDIIPMTU;
break;
#endif
#if NARC > 0
case IFT_ARCNET:
{
int arcipifmtu;
if (rt->rt_ifp->if_flags & IFF_LINK0)
arcipifmtu = arc_ipmtu;
else
arcipifmtu = ARCMTU;
if ((rt->rt_rmx.rmx_locks & RTV_MTU) == 0 &&
(rt->rt_rmx.rmx_mtu > arcipifmtu ||
(rt->rt_rmx.rmx_mtu == 0 &&
rt->rt_ifp->if_mtu > arcipifmtu)))
rt->rt_rmx.rmx_mtu = arcipifmtu;
break;
}
#endif
}
break;
}
/* Announce a new entry if requested. */
if (rt->rt_flags & RTF_ANNOUNCE)
arprequest(rt->rt_ifp,
&SIN(rt_key(rt))->sin_addr,
&SIN(rt_key(rt))->sin_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.
*/
switch (SDL(gate)->sdl_type) {
#if NTOKEN > 0
case IFT_ISO88025:
allocsize = sizeof(*la) + sizeof(struct token_rif);
break;
#endif /* NTOKEN > 0 */
default:
allocsize = sizeof(*la);
}
R_Malloc(la, struct llinfo_arp *, allocsize);
rt->rt_llinfo = (caddr_t)la;
if (la == 0) {
log(LOG_DEBUG, "arp_rtrequest: malloc failed\n");
break;
}
arp_inuse++, arp_allocated++;
Bzero(la, allocsize);
la->la_rt = rt;
rt->rt_flags |= RTF_LLINFO;
LIST_INSERT_HEAD(&llinfo_arp, la, la_list);
INADDR_TO_IA(SIN(rt_key(rt))->sin_addr, ia);
while (ia && ia->ia_ifp != rt->rt_ifp)
NEXT_IA_WITH_SAME_ADDR(ia);
if (ia) {
/*
* 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.
*
* In 4.4BSD, the above "if" statement checked
* rt->rt_ifa against rt_key(rt). It was changed
* to the current form so that we can provide a
* better support for multiple IPv4 addresses on a
* interface.
*/
rt->rt_expire = 0;
Bcopy(LLADDR(rt->rt_ifp->if_sadl),
LLADDR(SDL(gate)),
SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen);
#if NLOOP > 0
if (useloopback)
rt->rt_ifp = &loif[0];
#endif
/*
* make sure to set rt->rt_ifa to the interface
* address we are using, otherwise we will have trouble
* with source address selection.
*/
ifa = &ia->ia_ifa;
if (ifa != rt->rt_ifa) {
IFAFREE(rt->rt_ifa);
IFAREF(ifa);
rt->rt_ifa = ifa;
}
}
break;
case RTM_DELETE:
if (la == 0)
break;
arp_inuse--;
LIST_REMOVE(la, la_list);
rt->rt_llinfo = 0;
rt->rt_flags &= ~RTF_LLINFO;
s = splnet();
mold = la->la_hold;
la->la_hold = 0;
splx(s);
if (mold)
m_freem(mold);
Free((caddr_t)la);
}
ARP_UNLOCK();
}
/*
* Broadcast an ARP request. Caller specifies:
* - arp header source ip address
* - arp header target ip address
* - arp header source ethernet address
*/
static void
arprequest(ifp, sip, tip, enaddr)
struct ifnet *ifp;
struct in_addr *sip, *tip;
u_int8_t *enaddr;
{
struct mbuf *m;
struct arphdr *ah;
struct sockaddr sa;
if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL)
return;
MCLAIM(m, &arpdomain.dom_mowner);
switch (ifp->if_type) {
case IFT_IEEE1394:
m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
ifp->if_addrlen;
break;
default:
m->m_len = sizeof(*ah) + 2 * sizeof(struct in_addr) +
2 * ifp->if_addrlen;
break;
}
m->m_pkthdr.len = m->m_len;
MH_ALIGN(m, m->m_len);
ah = mtod(m, struct arphdr *);
bzero((caddr_t)ah, m->m_len);
switch (ifp->if_type) {
case IFT_IEEE1394: /* RFC2734 */
/* fill it now for ar_tpa computation */
ah->ar_hrd = htons(ARPHRD_IEEE1394);
break;
default:
/* ifp->if_output will fill ar_hrd */
break;
}
ah->ar_pro = htons(ETHERTYPE_IP);
ah->ar_hln = ifp->if_addrlen; /* hardware address length */
ah->ar_pln = sizeof(struct in_addr); /* protocol address length */
ah->ar_op = htons(ARPOP_REQUEST);
bcopy((caddr_t)enaddr, (caddr_t)ar_sha(ah), ah->ar_hln);
bcopy((caddr_t)sip, (caddr_t)ar_spa(ah), ah->ar_pln);
bcopy((caddr_t)tip, (caddr_t)ar_tpa(ah), ah->ar_pln);
sa.sa_family = AF_ARP;
sa.sa_len = 2;
m->m_flags |= M_BCAST;
arpstat.as_sndtotal++;
arpstat.as_sndrequest++;
(*ifp->if_output)(ifp, 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(ifp, rt, m, dst, desten)
struct ifnet *ifp;
struct rtentry *rt;
struct mbuf *m;
struct sockaddr *dst;
u_char *desten;
{
struct llinfo_arp *la;
struct sockaddr_dl *sdl;
struct mbuf *mold;
int s;
if (rt)
la = (struct llinfo_arp *)rt->rt_llinfo;
else {
if ((la = arplookup(m, &SIN(dst)->sin_addr, 1, 0)) != NULL)
rt = la->la_rt;
}
if (la == 0 || rt == 0) {
arpstat.as_allocfail++;
log(LOG_DEBUG,
"arpresolve: can't allocate llinfo on %s for %s\n",
ifp->if_xname, in_fmtaddr(SIN(dst)->sin_addr));
m_freem(m);
return (0);
}
sdl = SDL(rt->rt_gateway);
/*
* Check the address family and length is valid, the address
* is resolved; otherwise, try to resolve.
*/
if ((rt->rt_expire == 0 || rt->rt_expire > time.tv_sec) &&
sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) {
bcopy(LLADDR(sdl), desten,
min(sdl->sdl_alen, ifp->if_addrlen));
return 1;
}
/*
* There is an arptab entry, but no ethernet address
* response yet. Replace the held mbuf with this
* latest one.
*/
arpstat.as_dfrtotal++;
s = splnet();
mold = la->la_hold;
la->la_hold = m;
splx(s);
if (mold) {
arpstat.as_dfrdropped++;
m_freem(mold);
}
/*
* Re-send the ARP request when appropriate.
*/
#ifdef DIAGNOSTIC
if (rt->rt_expire == 0) {
/* This should never happen. (Should it? -gwr) */
printf("arpresolve: unresolved and rt_expire == 0\n");
/* Set expiration time to now (expired). */
rt->rt_expire = time.tv_sec;
}
#endif
if (rt->rt_expire) {
rt->rt_flags &= ~RTF_REJECT;
if (la->la_asked == 0 || rt->rt_expire != time.tv_sec) {
rt->rt_expire = time.tv_sec;
if (la->la_asked++ < arp_maxtries)
arprequest(ifp,
&SIN(rt->rt_ifa->ifa_addr)->sin_addr,
&SIN(dst)->sin_addr,
LLADDR(ifp->if_sadl));
else {
rt->rt_flags |= RTF_REJECT;
rt->rt_expire += arpt_down;
la->la_asked = 0;
}
}
}
return (0);
}
/*
* Common length and type checks are done here,
* then the protocol-specific routine is called.
*/
void
arpintr()
{
struct mbuf *m;
struct arphdr *ar;
int s;
int arplen;
while (arpintrq.ifq_head) {
s = splnet();
IF_DEQUEUE(&arpintrq, m);
splx(s);
if (m == 0 || (m->m_flags & M_PKTHDR) == 0)
panic("arpintr");
MCLAIM(m, &arpdomain.dom_mowner);
arpstat.as_rcvtotal++;
/*
* First, make sure we have at least struct arphdr.
*/
if (m->m_len < sizeof(struct arphdr) ||
(ar = mtod(m, struct arphdr *)) == NULL)
goto badlen;
switch (m->m_pkthdr.rcvif->if_type) {
case IFT_IEEE1394:
arplen = sizeof(struct arphdr) +
ar->ar_hln + 2 * ar->ar_pln;
break;
default:
arplen = sizeof(struct arphdr) +
2 * ar->ar_hln + 2 * ar->ar_pln;
break;
}
if (/* XXX ntohs(ar->ar_hrd) == ARPHRD_ETHER && */
m->m_len >= arplen)
switch (ntohs(ar->ar_pro)) {
case ETHERTYPE_IP:
case ETHERTYPE_IPTRAILERS:
in_arpinput(m);
continue;
default:
arpstat.as_rcvbadproto++;
}
else {
badlen:
arpstat.as_rcvbadlen++;
}
m_freem(m);
}
}
/*
* ARP for Internet protocols on 10 Mb/s Ethernet.
* Algorithm is that given in RFC 826.
* In addition, a sanity check is performed on the sender
* protocol address, to catch impersonators.
* We no longer handle negotiations for use of trailer protocol:
* Formerly, ARP replied for protocol type ETHERTYPE_TRAIL sent
* along with IP replies if we wanted trailers sent to us,
* and also sent them in response to IP replies.
* This allowed either end to announce the desire to receive
* trailer packets.
* We no longer reply to requests for ETHERTYPE_TRAIL protocol either,
* but formerly didn't normally send requests.
*/
static void
in_arpinput(m)
struct mbuf *m;
{
struct arphdr *ah;
struct ifnet *ifp = m->m_pkthdr.rcvif;
struct llinfo_arp *la = 0;
struct rtentry *rt;
struct in_ifaddr *ia;
#if NBRIDGE > 0
struct in_ifaddr *bridge_ia = NULL;
#endif
struct sockaddr_dl *sdl;
struct sockaddr sa;
struct in_addr isaddr, itaddr, myaddr;
int op;
struct mbuf *mold;
int s;
ah = mtod(m, struct arphdr *);
op = ntohs(ah->ar_op);
/*
* Fix up ah->ar_hrd if necessary, before using ar_tha() or
* ar_tpa().
*/
switch (ifp->if_type) {
case IFT_IEEE1394:
if (ntohs(ah->ar_hrd) == ARPHRD_IEEE1394)
;
else {
/* XXX this is to make sure we compute ar_tha right */
/* XXX check ar_hrd more strictly? */
ah->ar_hrd = htons(ARPHRD_IEEE1394);
}
break;
default:
/* XXX check ar_hrd? */
break;
}
bcopy((caddr_t)ar_spa(ah), (caddr_t)&isaddr, sizeof (isaddr));
bcopy((caddr_t)ar_tpa(ah), (caddr_t)&itaddr, sizeof (itaddr));
if (m->m_flags & (M_BCAST|M_MCAST))
arpstat.as_rcvmcast++;
/*
* If the target IP address is zero, ignore the packet.
* This prevents the code below from tring to answer
* when we are using IP address zero (booting).
*/
if (in_nullhost(itaddr)) {
arpstat.as_rcvzerotpa++;
goto out;
}
/*
* If the source IP address is zero, this is most likely a
* confused host trying to use IP address zero. (Windoze?)
* XXX: Should we bother trying to reply to these?
*/
if (in_nullhost(isaddr)) {
arpstat.as_rcvzerospa++;
goto out;
}
/*
* Search for a matching interface address
* or any address on the interface to use
* as a dummy address in the rest of this function
*/
INADDR_TO_IA(itaddr, ia);
while (ia != NULL) {
if (ia->ia_ifp == m->m_pkthdr.rcvif)
break;
#if NBRIDGE > 0
/*
* If the interface we received the packet on
* is part of a bridge, check to see if we need
* to "bridge" the packet to ourselves at this
* layer. Note we still prefer a perfect match,
* but allow this weaker match if necessary.
*/
if (m->m_pkthdr.rcvif->if_bridge != NULL &&
m->m_pkthdr.rcvif->if_bridge == ia->ia_ifp->if_bridge)
bridge_ia = ia;
#endif /* NBRIDGE > 0 */
NEXT_IA_WITH_SAME_ADDR(ia);
}
#if NBRIDGE > 0
if (ia == NULL && bridge_ia != NULL) {
ia = bridge_ia;
ifp = bridge_ia->ia_ifp;
}
#endif
if (ia == NULL) {
INADDR_TO_IA(isaddr, ia);
while ((ia != NULL) && ia->ia_ifp != m->m_pkthdr.rcvif)
NEXT_IA_WITH_SAME_ADDR(ia);
if (ia == NULL) {
IFP_TO_IA(ifp, ia);
if (ia == NULL) {
arpstat.as_rcvnoint++;
goto out;
}
}
}
myaddr = ia->ia_addr.sin_addr;
/* XXX checks for bridge case? */
if (!bcmp((caddr_t)ar_sha(ah), LLADDR(ifp->if_sadl),
ifp->if_addrlen)) {
arpstat.as_rcvlocalsha++;
goto out; /* it's from me, ignore it. */
}
/* XXX checks for bridge case? */
if (!bcmp((caddr_t)ar_sha(ah), (caddr_t)ifp->if_broadcastaddr,
ifp->if_addrlen)) {
arpstat.as_rcvbcastsha++;
log(LOG_ERR,
"%s: arp: link address is broadcast for IP address %s!\n",
ifp->if_xname, in_fmtaddr(isaddr));
goto out;
}
if (in_hosteq(isaddr, myaddr)) {
arpstat.as_rcvlocalspa++;
log(LOG_ERR,
"duplicate IP address %s sent from link address %s\n",
in_fmtaddr(isaddr), lla_snprintf(ar_sha(ah), ah->ar_hln));
itaddr = myaddr;
goto reply;
}
la = arplookup(m, &isaddr, in_hosteq(itaddr, myaddr), 0);
if (la && (rt = la->la_rt) && (sdl = SDL(rt->rt_gateway))) {
if (sdl->sdl_alen &&
bcmp((caddr_t)ar_sha(ah), LLADDR(sdl), sdl->sdl_alen)) {
if (rt->rt_flags & RTF_STATIC) {
arpstat.as_rcvoverperm++;
log(LOG_INFO,
"%s tried to overwrite permanent arp info"
" for %s\n",
lla_snprintf(ar_sha(ah), ah->ar_hln),
in_fmtaddr(isaddr));
goto out;
} else if (rt->rt_ifp != ifp) {
arpstat.as_rcvoverint++;
log(LOG_INFO,
"%s on %s tried to overwrite "
"arp info for %s on %s\n",
lla_snprintf(ar_sha(ah), ah->ar_hln),
ifp->if_xname, in_fmtaddr(isaddr),
rt->rt_ifp->if_xname);
goto out;
} else {
arpstat.as_rcvover++;
log(LOG_INFO,
"arp info overwritten for %s by %s\n",
in_fmtaddr(isaddr),
lla_snprintf(ar_sha(ah), ah->ar_hln));
}
}
/*
* sanity check for the address length.
* XXX this does not work for protocols with variable address
* length. -is
*/
if (sdl->sdl_alen &&
sdl->sdl_alen != ah->ar_hln) {
arpstat.as_rcvlenchg++;
log(LOG_WARNING,