/* * 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 1.35 1996/11/15 18:50:31 fenner Exp $ */ /* * Ethernet address resolution protocol. * TODO: * 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 #define SIN(s) ((struct sockaddr_in *)s) #define SDL(s) ((struct sockaddr_dl *)s) 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 *)); static 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 <= time.tv_sec) 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 = time.tv_sec; 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; register u_char *desten; struct rtentry *rt0; { register struct llinfo_arp *la; struct sockaddr_dl *sdl; if (m->m_flags & M_BCAST) { /* broadcast */ (void)memcpy(desten, etherbroadcastaddr, sizeof(etherbroadcastaddr)); return (1); } if (m->m_flags & M_MCAST) { /* multicast */ ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten); return(1); } if (rt) la = (struct llinfo_arp *)rt->rt_llinfo; else { la = arplookup(SIN(dst)->sin_addr.s_addr, 1, 0); if (la) rt = la->la_rt; } if (la == 0 || rt == 0) { log(LOG_DEBUG, "arpresolve: can't allocate llinfo for %s\n", inet_ntoa(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, sdl->sdl_alen); return 1; } /* * 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; 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(ac, &(SIN(rt->rt_ifa->ifa_addr)->sin_addr.s_addr), &(SIN(dst)->sin_addr.s_addr), ac->ac_enaddr); 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. */ static void arpintr(void) { register struct mbuf *m; register struct arphdr *ar; int s; while (arpintrq.ifq_head) { s = splimp(); IF_DEQUEUE(&arpintrq, m); splx(s); if (m == 0 || (m->m_flags & M_PKTHDR) == 0) panic("arpintr"); if (m->m_len >= sizeof(struct arphdr) && (ar = mtod(m, struct arphdr *)) && ntohs(ar->ar_hrd) == ARPHRD_ETHER && m->m_len >= sizeof(struct arphdr) + 2 * ar->ar_hln + 2 * ar->ar_pln) switch (ntohs(ar->ar_pro)) { case ETHERTYPE_IP: in_arpinput(m); continue; } m_freem(m); } } NETISR_SET(NETISR_ARP, arpintr); /* * 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; { register struct ether_arp *ea; register struct arpcom *ac = (struct arpcom *)m->m_pkthdr.rcvif; struct ether_header *eh; register struct llinfo_arp *la = 0; register struct rtentry *rt; struct in_ifaddr *ia, *maybe_ia = 0; struct sockaddr_dl *sdl; struct sockaddr sa; struct in_addr isaddr, itaddr, myaddr; int op; ea = mtod(m, struct ether_arp *); op = ntohs(ea->arp_op); (void)memcpy(&isaddr, ea->arp_spa, sizeof (isaddr)); (void)memcpy(&itaddr, ea->arp_tpa, sizeof (itaddr)); for (ia = in_ifaddrhead.tqh_first; 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) { m_freem(m); return; } 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))) { m_freem(m); /* it's from me, ignore it. */ return; } 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 %s!\n", inet_ntoa(isaddr)); m_freem(m); return; } if (isaddr.s_addr == myaddr.s_addr) { log(LOG_ERR, "arp: %6D is using my IP address %s!\n", ea->arp_sha, ":", inet_ntoa(isaddr)); itaddr = myaddr; goto reply; } la = arplookup(isaddr.s_addr, itaddr.s_addr == myaddr.s_addr, 0); if (la && (rt = la->la_rt) && (sdl = SDL(rt->rt_gateway))) { if (sdl->sdl_alen && bcmp((caddr_t)ea->arp_sha, LLADDR(sdl), sdl->sdl_alen)) log(LOG_INFO, "arp: %s moved from %6D to %6D\n", inet_ntoa(isaddr), (u_char *)LLADDR(sdl), ":", ea->arp_sha, ":"); (void)memcpy(LLADDR(sdl), ea->arp_sha, sizeof(ea->arp_sha)); sdl->sdl_alen = sizeof(ea->arp_sha); if (rt->rt_expire) rt->rt_expire = time.tv_sec + arpt_keep; rt->rt_flags &= ~RTF_REJECT; la->la_asked = 0; if (la->la_hold) { (*ac->ac_if.if_output)(&ac->ac_if, la->la_hold, rt_key(rt), rt); la->la_hold = 0; } } reply: if (op != ARPOP_REQUEST) { m_freem(m); return; } if (itaddr.s_addr == myaddr.s_addr) { /* I am the target */ (void)memcpy(ea->arp_tha, ea->arp_sha, sizeof(ea->arp_sha)); (void)memcpy(ea->arp_sha, ac->ac_enaddr, sizeof(ea->arp_sha)); } else { la = arplookup(itaddr.s_addr, 0, SIN_PROXY); if (la == NULL) { struct sockaddr_in sin; if (!arp_proxyall) { m_freem(m); return; } 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) { m_freem(m); return; } /* * 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 == &ac->ac_if) { rtfree(rt); m_freem(m); return; } (void)memcpy(ea->arp_tha, ea->arp_sha, sizeof(ea->arp_sha)); (void)memcpy(ea->arp_sha, ac->ac_enaddr, sizeof(ea->arp_sha)); rtfree(rt); #ifdef DEBUG_PROXY printf("arp: proxying for %s\n", inet_ntoa(itaddr)); #endif } else { rt = la->la_rt; (void)memcpy(ea->arp_tha, ea->arp_sha, sizeof(ea->arp_sha)); sdl = SDL(rt->rt_gateway); (void)memcpy(ea->arp_sha, LLADDR(sdl), sizeof(ea->arp_sha)); } } (void)memcpy(ea->arp_tpa, ea->arp_spa, sizeof(ea->arp_spa)); (void)memcpy(ea->arp_spa, &itaddr, sizeof(ea->arp_spa)); ea->arp_op = htons(ARPOP_REPLY); ea->arp_pro = htons(ETHERTYPE_IP); /* let's be sure! */ eh = (struct ether_header *)sa.sa_data; (void)memcpy(eh->ether_dhost, ea->arp_tha, sizeof(eh->ether_dhost)); eh->ether_type = htons(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); return; } /* * Free an arp entry. */ static void arptfree(la) register struct llinfo_arp *la; { register struct rtentry *rt = la->la_rt; register struct sockaddr_dl *sdl; if (rt == 0) panic("arptfree"); if (rt->rt_refcnt > 0 && (sdl = SDL(rt->rt_gateway)) && sdl->sdl_family == AF_LINK) { sdl->sdl_alen = 0; la->la_asked = 0; rt->rt_flags &= ~RTF_REJECT; return; } rtrequest(RTM_DELETE, rt_key(rt), (struct sockaddr *)0, rt_mask(rt), 0, (struct rtentry **)0); } /* * Lookup or enter a new address in arptab. */ static struct llinfo_arp * arplookup(addr, create, proxy) u_long addr; int create, proxy; { register struct rtentry *rt; static struct sockaddr_inarp sin = {sizeof(sin), AF_INET }; const char *why = 0; sin.sin_addr.s_addr = addr; sin.sin_other = proxy ? SIN_PROXY : 0; rt = rtalloc1((struct sockaddr *)&sin, create, 0UL); if (rt == 0) return (0); rt->rt_refcnt--; 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 && create) { log(LOG_DEBUG, "arplookup %s failed: %s\n", inet_ntoa(sin.sin_addr), why); return 0; } else if (why) { return 0; } return ((struct llinfo_arp *)rt->rt_llinfo); } void arp_ifinit(ac, ifa) struct arpcom *ac; struct ifaddr *ifa; { arprequest(ac, &(IA_SIN(ifa)->sin_addr.s_addr), &(IA_SIN(ifa)->sin_addr.s_addr), ac->ac_enaddr); ifa->ifa_rtrequest = arp_rtrequest; ifa->ifa_flags |= RTF_CLONING; }