/* * Copyright (c) 1982, 1986, 1988 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. * * from: @(#)if_ether.c 7.13 (Berkeley) 10/31/90 * $Id: if_arp.c,v 1.5 1993/12/18 00:41:48 mycroft Exp $ */ /* * Ethernet address resolution protocol. * TODO: * run at splnet (add ARP protocol intr.) * link entries onto hash chains, keep free list * add "inuse/lock" bit (or ref. count) along with valid bit */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef GATEWAY #define ARPTAB_BSIZ 16 /* bucket size */ #define ARPTAB_NB 37 /* number of buckets */ #else #define ARPTAB_BSIZ 9 /* bucket size */ #define ARPTAB_NB 19 /* number of buckets */ #endif #define ARPTAB_SIZE (ARPTAB_BSIZ * ARPTAB_NB) struct arptab arptab[ARPTAB_SIZE]; int arptab_size = ARPTAB_SIZE; /* for arp command */ /* * ARP trailer negotiation. Trailer protocol is not IP specific, * but ARP request/response use IP addresses. */ #define ETHERTYPE_IPTRAILERS ETHERTYPE_TRAIL #define ARPTAB_HASH(a) \ ((u_long)(a) % 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; \ } /* 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 */ extern struct ifnet loif; /* * Timeout routine. Age arp_tab entries once a minute. */ /* ARGSUSED */ void arptimer(caddr_t arg) { register struct arptab *at; register i; timeout(arptimer, (caddr_t)0, ARPT_AGE * hz); 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_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)); 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; sa.sa_len = sizeof(sa); (*ac->ac_if.if_output)(&ac->ac_if, m, &sa, (struct rtentry *)0); } int useloopback = 1; /* use loopback interface for local traffic */ /* * 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. * * 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, usetrailers) register struct arpcom *ac; struct mbuf *m; register struct in_addr *destip; register u_char *desten; int *usetrailers; { register struct arptab *at; struct sockaddr_in sin; register struct in_ifaddr *ia; u_long lna; int s; *usetrailers = 0; if (m->m_flags & M_BCAST) { /* broadcast */ bcopy((caddr_t)etherbroadcastaddr, (caddr_t)desten, sizeof(etherbroadcastaddr)); return (1); } #ifdef MULTICAST if (m->m_flags & M_MCAST) { /* multicast */ ETHER_MAP_IP_MULTICAST(destip, desten); return(1); } #endif lna = in_lnaof(*destip); /* if for us, use software loopback driver if up */ for (ia = in_ifaddr; ia; ia = ia->ia_next) if ((ia->ia_ifp == &ac->ac_if) && (destip->s_addr == ia->ia_addr.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" * to force traffic out to the hardware. */ if (useloopback) { sin.sin_family = AF_INET; sin.sin_addr = *destip; (void) looutput(&loif, m, (struct sockaddr *)&sin, 0); /* * The packet has already been sent and freed. */ return (0); } else { bcopy((caddr_t)ac->ac_enaddr, (caddr_t)desten, sizeof(ac->ac_enaddr)); return (1); } } s = splimp(); ARPTAB_LOOK(at, destip->s_addr); if (at == 0) { /* not found */ if (ac->ac_if.if_flags & IFF_NOARP) { 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); if (at == 0) panic("arpresolve: no free entry"); 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)); if (at->at_flags & ATF_USETRAILERS) *usetrailers = 1; 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. Common length and type checks are done here, * then the protocol-specific routine is called. */ arpinput(ac, m) struct arpcom *ac; struct mbuf *m; { register struct arphdr *ar; if (ac->ac_if.if_flags & IFF_NOARP) goto out; if (m->m_len < sizeof(struct arphdr)) goto out; ar = mtod(m, struct arphdr *); if (ntohs(ar->ar_hrd) != ARPHRD_ETHER) goto out; if (m->m_len < sizeof(struct arphdr) + 2 * ar->ar_hln + 2 * ar->ar_pln) goto out; switch (ntohs(ar->ar_pro)) { case ETHERTYPE_IP: case ETHERTYPE_IPTRAILERS: in_arpinput(ac, m); return; default: break; } out: 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 also handle negotiations for use of trailer protocol: * ARP replies for protocol type ETHERTYPE_TRAIL are sent * along with IP replies if we want trailers sent to us, * and also send them in response to IP replies. * This allows either end to announce the desire to receive * trailer packets. * We reply to requests for ETHERTYPE_TRAIL protocol as well, * but don't normally send requests. */ in_arpinput(ac, m) register struct arpcom *ac; struct mbuf *m; { register struct ether_arp *ea; struct ether_header *eh; register struct arptab *at; /* same as "merge" flag */ register struct in_ifaddr *ia; struct in_ifaddr *maybe_ia = 0; struct mbuf *mcopy = 0; struct sockaddr_in sin; struct sockaddr sa; struct in_addr isaddr, itaddr, myaddr; int proto, op, s, completed = 0; ea = mtod(m, struct ether_arp *); proto = ntohs(ea->arp_pro); op = ntohs(ea->arp_op); bcopy((caddr_t)ea->arp_spa, (caddr_t)&isaddr, sizeof (isaddr)); bcopy((caddr_t)ea->arp_tpa, (caddr_t)&itaddr, sizeof (itaddr)); for (ia = in_ifaddr; ia; ia = ia->ia_next) if (ia->ia_ifp == &ac->ac_if) { maybe_ia = ia; if ((itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) || (isaddr.s_addr == ia->ia_addr.sin_addr.s_addr)) break; } if (maybe_ia == 0) goto out; myaddr = ia ? ia->ia_addr.sin_addr : maybe_ia->ia_addr.sin_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 (!bcmp((caddr_t)ea->arp_sha, (caddr_t)etherbroadcastaddr, sizeof (ea->arp_sha))) { log(LOG_ERR, "arp: ether address is broadcast for IP address %x!\n", ntohl(isaddr.s_addr)); goto out; } if (isaddr.s_addr == myaddr.s_addr) { log(LOG_ERR, "duplicate IP address %x!! sent from ethernet address: %s\n", ntohl(isaddr.s_addr), ether_sprintf(ea->arp_sha)); itaddr = myaddr; if (op == ARPOP_REQUEST) goto reply; goto out; } s = splimp(); ARPTAB_LOOK(at, isaddr.s_addr); if (at) { bcopy((caddr_t)ea->arp_sha, (caddr_t)at->at_enaddr, sizeof(ea->arp_sha)); if ((at->at_flags & ATF_COM) == 0) completed = 1; 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, (struct rtentry *)0); at->at_hold = 0; } } if (at == 0 && itaddr.s_addr == myaddr.s_addr) { /* ensure we have a table entry */ if (at = arptnew(&isaddr)) { bcopy((caddr_t)ea->arp_sha, (caddr_t)at->at_enaddr, sizeof(ea->arp_sha)); completed = 1; at->at_flags |= ATF_COM; } } splx(s); reply: switch (proto) { case ETHERTYPE_IPTRAILERS: /* partner says trailers are OK */ if (at) at->at_flags |= ATF_USETRAILERS; /* * Reply to request iff we want trailers. */ if (op != ARPOP_REQUEST || ac->ac_if.if_flags & IFF_NOTRAILERS) goto out; break; case ETHERTYPE_IP: /* * Reply if this is an IP request, * or if we want to send a trailer response. * Send the latter only to the IP response * that completes the current ARP entry. */ if (op != ARPOP_REQUEST && (completed == 0 || ac->ac_if.if_flags & IFF_NOTRAILERS)) goto out; } if (itaddr.s_addr == myaddr.s_addr) { /* I am the target */ bcopy((caddr_t)ea->arp_sha, (caddr_t)ea->arp_tha, sizeof(ea->arp_sha)); bcopy((caddr_t)ac->ac_enaddr, (caddr_t)ea->arp_sha, sizeof(ea->arp_sha)); } else { ARPTAB_LOOK(at, itaddr.s_addr); if (at == NULL || (at->at_flags & ATF_PUBL) == 0) goto out; bcopy((caddr_t)ea->arp_sha, (caddr_t)ea->arp_tha, sizeof(ea->arp_sha)); bcopy((caddr_t)at->at_enaddr, (caddr_t)ea->arp_sha, sizeof(ea->arp_sha)); } bcopy((caddr_t)ea->arp_spa, (caddr_t)ea->arp_tpa, sizeof(ea->arp_spa)); bcopy((caddr_t)&itaddr, (caddr_t)ea->arp_spa, sizeof(ea->arp_spa)); ea->arp_op = htons(ARPOP_REPLY); /* * If incoming packet was an IP reply, * we are sending a reply for type IPTRAILERS. * If we are sending a reply for type IP * and we want to receive trailers, * send a trailer reply as well. */ if (op == ARPOP_REPLY) ea->arp_pro = htons(ETHERTYPE_IPTRAILERS); else if (proto == ETHERTYPE_IP && (ac->ac_if.if_flags & IFF_NOTRAILERS) == 0) mcopy = m_copy(m, 0, (int)M_COPYALL); 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; sa.sa_len = sizeof(sa); (*ac->ac_if.if_output)(&ac->ac_if, m, &sa, (struct rtentry *)0); if (mcopy) { ea = mtod(mcopy, struct ether_arp *); ea->arp_pro = htons(ETHERTYPE_IPTRAILERS); (*ac->ac_if.if_output)(&ac->ac_if, mcopy, &sa, (struct rtentry *)0); } 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). * MUST BE CALLED AT SPLIMP. */ struct arptab * arptnew(addr) struct in_addr *addr; { register n; int oldest = -1; 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 ((int) 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; sin = (struct sockaddr_in *)&ar->arp_ha; #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN if (sin->sin_family == 0 && sin->sin_len < 16) sin->sin_family = sin->sin_len; #endif sin->sin_len = sizeof(ar->arp_ha); sin = (struct sockaddr_in *)&ar->arp_pa; #if defined(COMPAT_43) && BYTE_ORDER != BIG_ENDIAN if (sin->sin_family == 0 && sin->sin_len < 16) sin->sin_family = sin->sin_len; #endif sin->sin_len = sizeof(ar->arp_pa); if (ar->arp_pa.sa_family != AF_INET || ar->arp_ha.sa_family != AF_UNSPEC) return (EAFNOSUPPORT); 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 (at == NULL) { splx(s); return (EADDRNOTAVAIL); } 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|ATF_USETRAILERS)); at->at_timer = 0; break; case SIOCDARP: /* delete entry */ arptfree(at); break; case SIOCGARP: /* get entry */ case OSIOCGARP: bcopy((caddr_t)at->at_enaddr, (caddr_t)ar->arp_ha.sa_data, sizeof(at->at_enaddr)); #ifdef COMPAT_43 if (cmd == OSIOCGARP) *(u_short *)&ar->arp_ha = ar->arp_ha.sa_family; #endif ar->arp_flags = at->at_flags; break; } splx(s); return (0); }