/*- * 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. * 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 * $FreeBSD$ */ /* * Ethernet address resolution protocol. * TODO: * add "inuse/lock" bit (or ref. count) along with valid bit */ #include "opt_inet.h" #include "opt_mac.h" #include "opt_carp.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef DEV_CARP #include #endif #include #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_keep = (20*60); /* once resolved, good for 20 more minutes */ SYSCTL_INT(_net_link_ether_inet, OID_AUTO, max_age, CTLFLAG_RW, &arpt_keep, 0, "ARP entry lifetime in seconds"); #define rt_expire rt_rmx.rmx_expire struct llinfo_arp { struct callout la_timer; struct rtentry *la_rt; struct mbuf *la_hold; /* last packet until resolved/timeout */ u_short la_preempt; /* countdown for pre-expiry arps */ u_short la_asked; /* # requests sent */ }; static struct ifqueue arpintrq; static int 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, "ARP resolution attempts before returning error"); SYSCTL_INT(_net_link_ether_inet, OID_AUTO, useloopback, CTLFLAG_RW, &useloopback, 0, "Use the loopback interface for local traffic"); SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW, &arp_proxyall, 0, "Enable proxy ARP for all suitable requests"); static void arp_init(void); static void arp_rtrequest(int, struct rtentry *, struct rt_addrinfo *); static void arprequest(struct ifnet *, struct in_addr *, struct in_addr *, u_char *); static void arpintr(struct mbuf *); static void arptimer(void *); static struct rtentry *arplookup(u_long, int, int); #ifdef INET static void in_arpinput(struct mbuf *); #endif /* * Timeout routine. */ static void arptimer(void *arg) { struct rtentry *rt = (struct rtentry *)arg; RT_LOCK_ASSERT(rt); /* * The lock is needed to close a theoretical race * between spontaneous expiry and intentional removal. * We still got an extra reference on rtentry, so can * safely pass pointers to its contents. */ RT_UNLOCK(rt); rtrequest(RTM_DELETE, rt_key(rt), NULL, rt_mask(rt), 0, NULL); } /* * Parallel to llc_rtrequest. */ static void arp_rtrequest(req, rt, info) int req; struct rtentry *rt; struct rt_addrinfo *info; { struct sockaddr *gate; struct llinfo_arp *la; static struct sockaddr_dl null_sdl = {sizeof(null_sdl), AF_LINK}; struct in_ifaddr *ia; struct ifaddr *ifa; RT_LOCK_ASSERT(rt); if (rt->rt_flags & RTF_GATEWAY) return; gate = rt->rt_gateway; la = (struct llinfo_arp *)rt->rt_llinfo; 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 && rt_mask(rt) != NULL && 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 = time_uptime; 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, "%s: bad gateway %s%s\n", __func__, inet_ntoa(SIN(rt_key(rt))->sin_addr), (gate->sa_family != AF_LINK) ? " (!AF_LINK)": ""); 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_Zalloc(la, struct llinfo_arp *, sizeof(*la)); rt->rt_llinfo = (caddr_t)la; if (la == 0) { log(LOG_DEBUG, "%s: malloc failed\n", __func__); break; } arp_allocated++; /* * We are storing a route entry outside of radix tree. So, * it can be found and accessed by other means than radix * lookup. The routing code assumes that any rtentry detached * from radix can be destroyed safely. To prevent this, we * add an additional reference. */ RT_ADDREF(rt); la->la_rt = rt; rt->rt_flags |= RTF_LLINFO; callout_init_mtx(&la->la_timer, &rt->rt_mtx, CALLOUT_RETURNUNLOCKED); #ifdef INET /* * 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)) && rt->rt_ifp->if_type != IFT_ARCNET) { 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)), rt->rt_ifp->if_broadcastaddr, rt->rt_ifp->if_addrlen); SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen; rt->rt_expire = 0; } #endif TAILQ_FOREACH(ia, &in_ifaddrhead, ia_link) { if (ia->ia_ifp == rt->rt_ifp && SIN(rt_key(rt))->sin_addr.s_addr == (IA_SIN(ia))->sin_addr.s_addr) break; } 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. */ rt->rt_expire = 0; bcopy(IF_LLADDR(rt->rt_ifp), LLADDR(SDL(gate)), SDL(gate)->sdl_alen = rt->rt_ifp->if_addrlen); if (useloopback) { rt->rt_ifp = loif; rt->rt_rmx.rmx_mtu = loif->if_mtu; } /* * 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 == NULL) /* XXX: at least CARP does this. */ break; callout_stop(&la->la_timer); rt->rt_llinfo = NULL; rt->rt_flags &= ~RTF_LLINFO; RT_REMREF(rt); 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(ifp, sip, tip, enaddr) struct ifnet *ifp; struct in_addr *sip, *tip; u_char *enaddr; { struct mbuf *m; struct arphdr *ah; struct sockaddr sa; if ((m = m_gethdr(M_DONTWAIT, MT_DATA)) == NULL) return; m->m_len = sizeof(*ah) + 2*sizeof(struct in_addr) + 2*ifp->if_data.ifi_addrlen; 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); #ifdef MAC mac_create_mbuf_linklayer(ifp, m); #endif 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; (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); return; } /* * Resolve an IP address into an ethernet address. * On input: * ifp is the interface we use * dst is the next hop, * rt0 is the route to the final destination (possibly useless) * m is the mbuf * desten is where we want the address. * * On success, desten is filled in and the function returns 0; * If the packet must be held pending resolution, we return EWOULDBLOCK * On other errors, we return the corresponding error code. */ int arpresolve(struct ifnet *ifp, struct rtentry *rt0, struct mbuf *m, struct sockaddr *dst, u_char *desten) { struct llinfo_arp *la = NULL; struct rtentry *rt = NULL; struct sockaddr_dl *sdl; int error; if (m->m_flags & M_BCAST) { /* broadcast */ (void)memcpy(desten, ifp->if_broadcastaddr, ifp->if_addrlen); return (0); } if (m->m_flags & M_MCAST && ifp->if_type != IFT_ARCNET) {/* multicast */ ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); return (0); } if (rt0 != NULL) { error = rt_check(&rt, &rt0, dst); if (error) { m_freem(m); return error; } la = (struct llinfo_arp *)rt->rt_llinfo; if (la == NULL) RT_UNLOCK(rt); } if (la == NULL) { /* * We enter this block in case if rt0 was NULL, * or if rt found by rt_check() didn't have llinfo. */ rt = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0); if (rt == NULL) { log(LOG_DEBUG, "arpresolve: can't allocate route for %s\n", inet_ntoa(SIN(dst)->sin_addr)); m_freem(m); return (EINVAL); /* XXX */ } la = (struct llinfo_arp *)rt->rt_llinfo; if (la == NULL) { RT_UNLOCK(rt); log(LOG_DEBUG, "arpresolve: can't allocate llinfo for %s\n", inet_ntoa(SIN(dst)->sin_addr)); m_freem(m); return (EINVAL); /* XXX */ } } 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_uptime) && sdl->sdl_family == AF_LINK && sdl->sdl_alen != 0) { bcopy(LLADDR(sdl), desten, sdl->sdl_alen); /* * If entry has an expiry time and it is approaching, * send an ARP request. */ if ((rt->rt_expire != 0) && (time_uptime + la->la_preempt > rt->rt_expire)) { struct in_addr sin = SIN(rt->rt_ifa->ifa_addr)->sin_addr; la->la_preempt--; RT_UNLOCK(rt); arprequest(ifp, &sin, &SIN(dst)->sin_addr, IF_LLADDR(ifp)); return (0); } RT_UNLOCK(rt); return (0); } /* * If ARP is disabled or static on this interface, stop. * XXX * Probably should not allocate empty llinfo struct if we are * not going to be sending out an arp request. */ if (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) { RT_UNLOCK(rt); m_freem(m); return (EINVAL); } /* * There is an arptab entry, but no ethernet address * response yet. Replace the held mbuf with this * latest one. */ if (la->la_hold) m_freem(la->la_hold); la->la_hold = m; KASSERT(rt->rt_expire > 0, ("sending ARP request for static entry")); /* * Return EWOULDBLOCK if we have tried less than arp_maxtries. It * will be masked by ether_output(). Return EHOSTDOWN/EHOSTUNREACH * if we have already sent arp_maxtries ARP requests. Retransmit the * ARP request, but not faster than one request per second. */ if (la->la_asked < arp_maxtries) error = EWOULDBLOCK; /* First request. */ else error = (rt == rt0) ? EHOSTDOWN : EHOSTUNREACH; if (la->la_asked == 0 || rt->rt_expire != time_uptime) { struct in_addr sin = SIN(rt->rt_ifa->ifa_addr)->sin_addr; rt->rt_expire = time_uptime; callout_reset(&la->la_timer, hz, arptimer, rt); la->la_asked++; RT_UNLOCK(rt); arprequest(ifp, &sin, &SIN(dst)->sin_addr, IF_LLADDR(ifp)); } else RT_UNLOCK(rt); return (error); } /* * Common length and type checks are done here, * then the protocol-specific routine is called. */ static void arpintr(struct mbuf *m) { struct arphdr *ar; if (m->m_len < sizeof(struct arphdr) && ((m = m_pullup(m, sizeof(struct arphdr))) == NULL)) { log(LOG_ERR, "arp: runt packet -- m_pullup failed\n"); return; } ar = mtod(m, struct arphdr *); if (ntohs(ar->ar_hrd) != ARPHRD_ETHER && ntohs(ar->ar_hrd) != ARPHRD_IEEE802 && ntohs(ar->ar_hrd) != ARPHRD_ARCNET && ntohs(ar->ar_hrd) != ARPHRD_IEEE1394) { log(LOG_ERR, "arp: unknown hardware address format (0x%2D)\n", (unsigned char *)&ar->ar_hrd, ""); m_freem(m); return; } if (m->m_len < arphdr_len(ar)) { if ((m = m_pullup(m, arphdr_len(ar))) == NULL) { log(LOG_ERR, "arp: runt packet\n"); m_freem(m); return; } ar = mtod(m, struct arphdr *); } switch (ntohs(ar->ar_pro)) { #ifdef INET case ETHERTYPE_IP: in_arpinput(m); return; #endif } m_freem(m); } #ifdef INET /* * 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 int log_arp_wrong_iface = 1; static int log_arp_movements = 1; static int log_arp_permanent_modify = 1; SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, &log_arp_wrong_iface, 0, "log arp packets arriving on the wrong interface"); SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, &log_arp_movements, 0, "log arp replies from MACs different than the one in the cache"); SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, &log_arp_permanent_modify, 0, "log arp replies from MACs different than the one in the permanent arp entry"); static void in_arpinput(m) struct mbuf *m; { struct arphdr *ah; struct ifnet *ifp = m->m_pkthdr.rcvif; struct llinfo_arp *la; struct rtentry *rt; struct ifaddr *ifa; struct in_ifaddr *ia; struct sockaddr_dl *sdl; struct sockaddr sa; struct in_addr isaddr, itaddr, myaddr; struct mbuf *hold; u_int8_t *enaddr = NULL; int op, rif_len; int req_len; int bridged = 0; #ifdef DEV_CARP int carp_match = 0; #endif if (ifp->if_bridge) bridged = 1; req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); if (m->m_len < req_len && (m = m_pullup(m, req_len)) == NULL) { log(LOG_ERR, "in_arp: runt packet -- m_pullup failed\n"); return; } ah = mtod(m, struct arphdr *); op = ntohs(ah->ar_op); (void)memcpy(&isaddr, ar_spa(ah), sizeof (isaddr)); (void)memcpy(&itaddr, ar_tpa(ah), sizeof (itaddr)); /* * For a bridge, we want to check the address irrespective * of the receive interface. (This will change slightly * when we have clusters of interfaces). * If the interface does not match, but the recieving interface * is part of carp, we call carp_iamatch to see if this is a * request for the virtual host ip. * XXX: This is really ugly! */ LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash) { if (((bridged && ia->ia_ifp->if_bridge != NULL) || (ia->ia_ifp == ifp)) && itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) goto match; #ifdef DEV_CARP if (ifp->if_carp != NULL && carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) && itaddr.s_addr == ia->ia_addr.sin_addr.s_addr) { carp_match = 1; goto match; } #endif } LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) if (((bridged && ia->ia_ifp->if_bridge != NULL) || (ia->ia_ifp == ifp)) && isaddr.s_addr == ia->ia_addr.sin_addr.s_addr) goto match; /* * No match, use the first inet address on the receive interface * as a dummy address for the rest of the function. */ TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) if (ifa->ifa_addr->sa_family == AF_INET) { ia = ifatoia(ifa); goto match; } /* * If bridging, fall back to using any inet address. */ if (!bridged || (ia = TAILQ_FIRST(&in_ifaddrhead)) == NULL) goto drop; match: if (!enaddr) enaddr = (u_int8_t *)IF_LLADDR(ifp); myaddr = ia->ia_addr.sin_addr; if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) goto drop; /* it's from me, ignore it. */ if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) { log(LOG_ERR, "arp: link address is broadcast for IP address %s!\n", inet_ntoa(isaddr)); goto drop; } /* * Warn if another host is using the same IP address, but only if the * IP address isn't 0.0.0.0, which is used for DHCP only, in which * case we suppress the warning to avoid false positive complaints of * potential misconfiguration. */ if (!bridged && isaddr.s_addr == myaddr.s_addr && myaddr.s_addr != 0) { log(LOG_ERR, "arp: %*D is using my IP address %s!\n", ifp->if_addrlen, (u_char *)ar_sha(ah), ":", inet_ntoa(isaddr)); itaddr = myaddr; goto reply; } if (ifp->if_flags & IFF_STATICARP) goto reply; rt = arplookup(isaddr.s_addr, itaddr.s_addr == myaddr.s_addr, 0); if (rt != NULL) { la = (struct llinfo_arp *)rt->rt_llinfo; if (la == NULL) { RT_UNLOCK(rt); goto reply; } } else goto reply; /* The following is not an error when doing bridging. */ if (!bridged && rt->rt_ifp != ifp #ifdef DEV_CARP && (ifp->if_type != IFT_CARP || !carp_match) #endif ) { if (log_arp_wrong_iface) log(LOG_ERR, "arp: %s is on %s but got reply from %*D on %s\n", inet_ntoa(isaddr), rt->rt_ifp->if_xname, ifp->if_addrlen, (u_char *)ar_sha(ah), ":", ifp->if_xname); RT_UNLOCK(rt); goto reply; } sdl = SDL(rt->rt_gateway); if (sdl->sdl_alen && bcmp(ar_sha(ah), LLADDR(sdl), sdl->sdl_alen)) { if (rt->rt_expire) { if (log_arp_movements) log(LOG_INFO, "arp: %s moved from %*D to %*D on %s\n", inet_ntoa(isaddr), ifp->if_addrlen, (u_char *)LLADDR(sdl), ":", ifp->if_addrlen, (u_char *)ar_sha(ah), ":", ifp->if_xname); } else { RT_UNLOCK(rt); if (log_arp_permanent_modify) log(LOG_ERR, "arp: %*D attempts to modify " "permanent entry for %s on %s\n", ifp->if_addrlen, (u_char *)ar_sha(ah), ":", inet_ntoa(isaddr), ifp->if_xname); goto reply; } } /* * 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) { log(LOG_WARNING, "arp from %*D: new addr len %d, was %d", ifp->if_addrlen, (u_char *) ar_sha(ah), ":", ah->ar_hln, sdl->sdl_alen); } if (ifp->if_addrlen != ah->ar_hln) { log(LOG_WARNING, "arp from %*D: addr len: new %d, i/f %d (ignored)", ifp->if_addrlen, (u_char *) ar_sha(ah), ":", ah->ar_hln, ifp->if_addrlen); RT_UNLOCK(rt); goto reply; } (void)memcpy(LLADDR(sdl), ar_sha(ah), sdl->sdl_alen = ah->ar_hln); /* * If we receive an arp from a token-ring station over * a token-ring nic then try to save the source * routing info. */ if (ifp->if_type == IFT_ISO88025) { struct iso88025_header *th = NULL; struct iso88025_sockaddr_dl_data *trld; th = (struct iso88025_header *)m->m_pkthdr.header; trld = SDL_ISO88025(sdl); rif_len = TR_RCF_RIFLEN(th->rcf); if ((th->iso88025_shost[0] & TR_RII) && (rif_len > 2)) { trld->trld_rcf = th->rcf; trld->trld_rcf ^= htons(TR_RCF_DIR); memcpy(trld->trld_route, th->rd, rif_len - 2); trld->trld_rcf &= ~htons(TR_RCF_BCST_MASK); /* * Set up source routing information for * reply packet (XXX) */ m->m_data -= rif_len; m->m_len += rif_len; m->m_pkthdr.len += rif_len; } else { th->iso88025_shost[0] &= ~TR_RII; trld->trld_rcf = 0; } m->m_data -= 8; m->m_len += 8; m->m_pkthdr.len += 8; th->rcf = trld->trld_rcf; } if (rt->rt_expire) { rt->rt_expire = time_uptime + arpt_keep; callout_reset(&la->la_timer, hz * arpt_keep, arptimer, rt); } la->la_asked = 0; la->la_preempt = arp_maxtries; hold = la->la_hold; la->la_hold = NULL; RT_UNLOCK(rt); if (hold != NULL) (*ifp->if_output)(ifp, hold, rt_key(rt), rt); reply: if (op != ARPOP_REQUEST) goto drop; if (itaddr.s_addr == myaddr.s_addr) { /* I am the target */ (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); } else { rt = arplookup(itaddr.s_addr, 0, SIN_PROXY); if (rt == NULL) { struct sockaddr_in sin; if (!arp_proxyall) goto drop; bzero(&sin, sizeof sin); sin.sin_family = AF_INET; sin.sin_len = sizeof sin; sin.sin_addr = itaddr; rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL); if (!rt) goto drop; /* * Don't send proxies for nodes on the same interface * as this one came out of, or we'll get into a fight * over who claims what Ether address. */ if (rt->rt_ifp == ifp) { rtfree(rt); goto drop; } (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); (void)memcpy(ar_sha(ah), enaddr, ah->ar_hln); rtfree(rt); /* * Also check that the node which sent the ARP packet * is on the the interface we expect it to be on. This * avoids ARP chaos if an interface is connected to the * wrong network. */ sin.sin_addr = isaddr; rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL); if (!rt) goto drop; if (rt->rt_ifp != ifp) { log(LOG_INFO, "arp_proxy: ignoring request" " from %s via %s, expecting %s\n", inet_ntoa(isaddr), ifp->if_xname, rt->rt_ifp->if_xname); rtfree(rt); goto drop; } rtfree(rt); #ifdef DEBUG_PROXY printf("arp: proxying for %s\n", inet_ntoa(itaddr)); #endif } else { /* * Return proxied ARP replies only on the interface * or bridge cluster where this network resides. * Otherwise we may conflict with the host we are * proxying for. */ if (rt->rt_ifp != ifp && (rt->rt_ifp->if_bridge != ifp->if_bridge || ifp->if_bridge == NULL)) { RT_UNLOCK(rt); goto drop; } sdl = SDL(rt->rt_gateway); (void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); (void)memcpy(ar_sha(ah), LLADDR(sdl), ah->ar_hln); RT_UNLOCK(rt); } } if (itaddr.s_addr == myaddr.s_addr && IN_LINKLOCAL(ntohl(itaddr.s_addr))) { /* RFC 3927 link-local IPv4; always reply by broadcast. */ #ifdef DEBUG_LINKLOCAL printf("arp: sending reply for link-local addr %s\n", inet_ntoa(itaddr)); #endif m->m_flags |= M_BCAST; m->m_flags &= ~M_MCAST; } else { /* default behaviour; never reply by broadcast. */ m->m_flags &= ~(M_BCAST|M_MCAST); } (void)memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); (void)memcpy(ar_spa(ah), &itaddr, ah->ar_pln); ah->ar_op = htons(ARPOP_REPLY); ah->ar_pro = htons(ETHERTYPE_IP); /* let's be sure! */ m->m_len = sizeof(*ah) + (2 * ah->ar_pln) + (2 * ah->ar_hln); m->m_pkthdr.len = m->m_len; sa.sa_family = AF_ARP; sa.sa_len = 2; (*ifp->if_output)(ifp, m, &sa, (struct rtentry *)0); return; drop: m_freem(m); } #endif /* * Lookup or enter a new address in arptab. */ static struct rtentry * arplookup(addr, create, proxy) u_long addr; int create, proxy; { struct rtentry *rt; struct sockaddr_inarp sin; const char *why = 0; bzero(&sin, sizeof(sin)); sin.sin_len = sizeof(sin); sin.sin_family = AF_INET; sin.sin_addr.s_addr = addr; if (proxy) sin.sin_other = SIN_PROXY; rt = rtalloc1((struct sockaddr *)&sin, create, 0UL); if (rt == 0) return (0); if (rt->rt_flags & RTF_GATEWAY) why = "host is not on local network"; else if ((rt->rt_flags & RTF_LLINFO) == 0) why = "could not allocate llinfo"; else if (rt->rt_gateway->sa_family != AF_LINK) why = "gateway route is not ours"; if (why) { #define ISDYNCLONE(_rt) \ (((_rt)->rt_flags & (RTF_STATIC | RTF_WASCLONED)) == RTF_WASCLONED) if (create) log(LOG_DEBUG, "arplookup %s failed: %s\n", inet_ntoa(sin.sin_addr), why); /* * If there are no references to this Layer 2 route, * and it is a cloned route, and not static, and * arplookup() is creating the route, then purge * it from the routing table as it is probably bogus. */ if (rt->rt_refcnt == 1 && ISDYNCLONE(rt)) rtexpunge(rt); RTFREE_LOCKED(rt); return (0); #undef ISDYNCLONE } else { RT_REMREF(rt); return (rt); } } void arp_ifinit(ifp, ifa) struct ifnet *ifp; struct ifaddr *ifa; { if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) arprequest(ifp, &IA_SIN(ifa)->sin_addr, &IA_SIN(ifa)->sin_addr, IF_LLADDR(ifp)); ifa->ifa_rtrequest = arp_rtrequest; ifa->ifa_flags |= RTF_CLONING; } void arp_ifinit2(ifp, ifa, enaddr) struct ifnet *ifp; struct ifaddr *ifa; u_char *enaddr; { if (ntohl(IA_SIN(ifa)->sin_addr.s_addr) != INADDR_ANY) arprequest(ifp, &IA_SIN(ifa)->sin_addr, &IA_SIN(ifa)->sin_addr, enaddr); ifa->ifa_rtrequest = arp_rtrequest; ifa->ifa_flags |= RTF_CLONING; } static void arp_init(void) { arpintrq.ifq_maxlen = 50; mtx_init(&arpintrq.ifq_mtx, "arp_inq", NULL, MTX_DEF); netisr_register(NETISR_ARP, arpintr, &arpintrq, NETISR_MPSAFE); } SYSINIT(arp, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, arp_init, 0);