/* * 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: @(#)ip_input.c 7.19 (Berkeley) 5/25/91 * $Id: ip_input.c,v 1.3.4.1 1993/09/24 08:54:56 mycroft Exp $ */ #include "param.h" #include "systm.h" #include "malloc.h" #include "mbuf.h" #include "domain.h" #include "protosw.h" #include "socket.h" #include "errno.h" #include "time.h" #include "kernel.h" #include "machine/cpu.h" #include "../net/if.h" #include "../net/route.h" #include "in.h" #include "in_systm.h" #include "ip.h" #include "in_pcb.h" #include "in_var.h" #include "ip_var.h" #include "ip_icmp.h" #ifndef IPFORWARDING #ifdef GATEWAY #define IPFORWARDING 1 /* forward IP packets not for us */ #else /* GATEWAY */ #define IPFORWARDING 0 /* don't forward IP packets not for us */ #endif /* GATEWAY */ #endif /* IPFORWARDING */ #ifndef IPSENDREDIRECTS #define IPSENDREDIRECTS 1 #endif int ipforwarding = IPFORWARDING; int ipsendredirects = IPSENDREDIRECTS; #ifdef DIAGNOSTIC int ipprintfs = 0; #endif extern struct domain inetdomain; extern struct protosw inetsw[]; u_char ip_protox[IPPROTO_MAX]; int ipqmaxlen = IFQ_MAXLEN; struct in_ifaddr *in_ifaddr; /* first inet address */ /* * We need to save the IP options in case a protocol wants to respond * to an incoming packet over the same route if the packet got here * using IP source routing. This allows connection establishment and * maintenance when the remote end is on a network that is not known * to us. */ int ip_nhops = 0; static struct ip_srcrt { struct in_addr dst; /* final destination */ char nop; /* one NOP to align */ char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */ struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)]; } ip_srcrt; #ifdef GATEWAY extern int if_index; u_long *ip_ifmatrix; #endif /* * IP initialization: fill in IP protocol switch table. * All protocols not implemented in kernel go to raw IP protocol handler. */ ip_init() { register struct protosw *pr; register int i; pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); if (pr == 0) panic("ip_init"); for (i = 0; i < IPPROTO_MAX; i++) ip_protox[i] = pr - inetsw; for (pr = inetdomain.dom_protosw; pr < inetdomain.dom_protoswNPROTOSW; pr++) if (pr->pr_domain->dom_family == PF_INET && pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) ip_protox[pr->pr_protocol] = pr - inetsw; ipq.next = ipq.prev = &ipq; ip_id = time.tv_sec & 0xffff; ipintrq.ifq_maxlen = ipqmaxlen; #ifdef GATEWAY i = (if_index + 1) * (if_index + 1) * sizeof (u_long); if ((ip_ifmatrix = (u_long *) malloc(i, M_RTABLE, M_WAITOK)) == 0) panic("no memory for ip_ifmatrix"); #endif } struct ip *ip_reass(); struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; struct route ipforward_rt; /* * Ip input routine. Checksum and byte swap header. If fragmented * try to reassemble. Process options. Pass to next level. */ ipintr() { register struct ip *ip; register struct mbuf *m; register struct ipq *fp; register struct in_ifaddr *ia; int hlen, s; #ifdef PARANOID static int busy = 0; if (busy) panic("ipintr: called recursively\n"); ++busy; #endif next: /* * Get next datagram off input queue and get IP header * in first mbuf. */ s = splimp(); IF_DEQUEUE(&ipintrq, m); splx(s); if (m == 0) { #ifdef PARANOID --busy; #endif return; } #ifdef DIAGNOSTIC if ((m->m_flags & M_PKTHDR) == 0) panic("ipintr no HDR"); #endif /* * If no IP addresses have been set yet but the interfaces * are receiving, can't do anything with incoming packets yet. */ if (in_ifaddr == NULL) goto bad; ipstat.ips_total++; if (m->m_len < sizeof (struct ip) && (m = m_pullup(m, sizeof (struct ip))) == 0) { ipstat.ips_toosmall++; goto next; } ip = mtod(m, struct ip *); hlen = ip->ip_hl << 2; if (hlen < sizeof(struct ip)) { /* minimum header length */ ipstat.ips_badhlen++; goto bad; } if (hlen > m->m_len) { if ((m = m_pullup(m, hlen)) == 0) { ipstat.ips_badhlen++; goto next; } ip = mtod(m, struct ip *); } if (ip->ip_sum = in_cksum(m, hlen)) { ipstat.ips_badsum++; goto bad; } /* * Convert fields to host representation. */ NTOHS(ip->ip_len); if (ip->ip_len < hlen) { ipstat.ips_badlen++; goto bad; } NTOHS(ip->ip_id); NTOHS(ip->ip_off); /* * Check that the amount of data in the buffers * is as at least much as the IP header would have us expect. * Trim mbufs if longer than we expect. * Drop packet if shorter than we expect. */ if (m->m_pkthdr.len < ip->ip_len) { ipstat.ips_tooshort++; goto bad; } if (m->m_pkthdr.len > ip->ip_len) { if (m->m_len == m->m_pkthdr.len) { m->m_len = ip->ip_len; m->m_pkthdr.len = ip->ip_len; } else m_adj(m, ip->ip_len - m->m_pkthdr.len); } /* * Process options and, if not destined for us, * ship it on. ip_dooptions returns 1 when an * error was detected (causing an icmp message * to be sent and the original packet to be freed). */ ip_nhops = 0; /* for source routed packets */ if (hlen > sizeof (struct ip) && ip_dooptions(m)) goto next; /* * Check our list of addresses, to see if the packet is for us. */ for (ia = in_ifaddr; ia; ia = ia->ia_next) { #define satosin(sa) ((struct sockaddr_in *)(sa)) if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr) goto ours; if ( #ifdef DIRECTED_BROADCAST ia->ia_ifp == m->m_pkthdr.rcvif && #endif (ia->ia_ifp->if_flags & IFF_BROADCAST)) { u_long t; if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == ip->ip_dst.s_addr) goto ours; if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr) goto ours; /* * Look for all-0's host part (old broadcast addr), * either for subnet or net. */ t = ntohl(ip->ip_dst.s_addr); if (t == ia->ia_subnet) goto ours; if (t == ia->ia_net) goto ours; } } if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) goto ours; if (ip->ip_dst.s_addr == INADDR_ANY) goto ours; /* * Not for us; forward if possible and desirable. */ if (ipforwarding == 0) { ipstat.ips_cantforward++; m_freem(m); } else ip_forward(m, 0); goto next; ours: /* * If offset or IP_MF are set, must reassemble. * Otherwise, nothing need be done. * (We could look in the reassembly queue to see * if the packet was previously fragmented, * but it's not worth the time; just let them time out.) */ if (ip->ip_off &~ IP_DF) { if (m->m_flags & M_EXT) { /* XXX */ if ((m = m_pullup(m, sizeof (struct ip))) == 0) { ipstat.ips_toosmall++; goto next; } ip = mtod(m, struct ip *); } /* * Look for queue of fragments * of this datagram. */ for (fp = ipq.next; fp != &ipq; fp = fp->next) if (ip->ip_id == fp->ipq_id && ip->ip_src.s_addr == fp->ipq_src.s_addr && ip->ip_dst.s_addr == fp->ipq_dst.s_addr && ip->ip_p == fp->ipq_p) goto found; fp = 0; found: /* * Adjust ip_len to not reflect header, * set ip_mff if more fragments are expected, * convert offset of this to bytes. */ ip->ip_len -= hlen; ((struct ipasfrag *)ip)->ipf_mff = 0; if (ip->ip_off & IP_MF) ((struct ipasfrag *)ip)->ipf_mff = 1; ip->ip_off <<= 3; /* * If datagram marked as having more fragments * or if this is not the first fragment, * attempt reassembly; if it succeeds, proceed. */ if (((struct ipasfrag *)ip)->ipf_mff || ip->ip_off) { ipstat.ips_fragments++; ip = ip_reass((struct ipasfrag *)ip, fp); if (ip == 0) goto next; else ipstat.ips_reassembled++; m = dtom(ip); } else if (fp) ip_freef(fp); } else ip->ip_len -= hlen; /* * Switch out to protocol's input routine. */ ipstat.ips_delivered++; (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); goto next; bad: m_freem(m); goto next; } /* * Take incoming datagram fragment and try to * reassemble it into whole datagram. If a chain for * reassembly of this datagram already exists, then it * is given as fp; otherwise have to make a chain. */ struct ip * ip_reass(ip, fp) register struct ipasfrag *ip; register struct ipq *fp; { register struct mbuf *m = dtom(ip); register struct ipasfrag *q; struct mbuf *t; int hlen = ip->ip_hl << 2; int i, next; /* * Presence of header sizes in mbufs * would confuse code below. */ m->m_data += hlen; m->m_len -= hlen; /* * If first fragment to arrive, create a reassembly queue. */ if (fp == 0) { if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL) goto dropfrag; fp = mtod(t, struct ipq *); insque(fp, &ipq); fp->ipq_ttl = IPFRAGTTL; fp->ipq_p = ip->ip_p; fp->ipq_id = ip->ip_id; fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp; fp->ipq_src = ((struct ip *)ip)->ip_src; fp->ipq_dst = ((struct ip *)ip)->ip_dst; q = (struct ipasfrag *)fp; goto insert; } /* * Find a segment which begins after this one does. */ for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) if (q->ip_off > ip->ip_off) break; /* * If there is a preceding segment, it may provide some of * our data already. If so, drop the data from the incoming * segment. If it provides all of our data, drop us. */ if (q->ipf_prev != (struct ipasfrag *)fp) { i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off; if (i > 0) { if (i >= ip->ip_len) goto dropfrag; m_adj(dtom(ip), i); ip->ip_off += i; ip->ip_len -= i; } } /* * While we overlap succeeding segments trim them or, * if they are completely covered, dequeue them. */ while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) { i = (ip->ip_off + ip->ip_len) - q->ip_off; if (i < q->ip_len) { q->ip_len -= i; q->ip_off += i; m_adj(dtom(q), i); break; } q = q->ipf_next; m_freem(dtom(q->ipf_prev)); ip_deq(q->ipf_prev); } insert: /* * Stick new segment in its place; * check for complete reassembly. */ ip_enq(ip, q->ipf_prev); next = 0; for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) { if (q->ip_off != next) return (0); next += q->ip_len; } if (q->ipf_prev->ipf_mff) return (0); /* * Reassembly is complete; concatenate fragments. */ q = fp->ipq_next; m = dtom(q); t = m->m_next; m->m_next = 0; m_cat(m, t); q = q->ipf_next; while (q != (struct ipasfrag *)fp) { t = dtom(q); q = q->ipf_next; m_cat(m, t); } /* * Create header for new ip packet by * modifying header of first packet; * dequeue and discard fragment reassembly header. * Make header visible. */ ip = fp->ipq_next; ip->ip_len = next; ((struct ip *)ip)->ip_src = fp->ipq_src; ((struct ip *)ip)->ip_dst = fp->ipq_dst; remque(fp); (void) m_free(dtom(fp)); m = dtom(ip); m->m_len += (ip->ip_hl << 2); m->m_data -= (ip->ip_hl << 2); /* some debugging cruft by sklower, below, will go away soon */ if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ register int plen = 0; for (t = m; m; m = m->m_next) plen += m->m_len; t->m_pkthdr.len = plen; } return ((struct ip *)ip); dropfrag: ipstat.ips_fragdropped++; m_freem(m); return (0); } /* * Free a fragment reassembly header and all * associated datagrams. */ ip_freef(fp) struct ipq *fp; { register struct ipasfrag *q, *p; for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) { p = q->ipf_next; ip_deq(q); m_freem(dtom(q)); } remque(fp); (void) m_free(dtom(fp)); } /* * Put an ip fragment on a reassembly chain. * Like insque, but pointers in middle of structure. */ ip_enq(p, prev) register struct ipasfrag *p, *prev; { p->ipf_prev = prev; p->ipf_next = prev->ipf_next; prev->ipf_next->ipf_prev = p; prev->ipf_next = p; } /* * To ip_enq as remque is to insque. */ ip_deq(p) register struct ipasfrag *p; { p->ipf_prev->ipf_next = p->ipf_next; p->ipf_next->ipf_prev = p->ipf_prev; } /* * IP timer processing; * if a timer expires on a reassembly * queue, discard it. */ ip_slowtimo() { register struct ipq *fp; int s = splnet(); fp = ipq.next; if (fp == 0) { splx(s); return; } while (fp != &ipq) { --fp->ipq_ttl; fp = fp->next; if (fp->prev->ipq_ttl == 0) { ipstat.ips_fragtimeout++; ip_freef(fp->prev); } } splx(s); } /* * Drain off all datagram fragments. */ ip_drain() { while (ipq.next != &ipq) { ipstat.ips_fragdropped++; ip_freef(ipq.next); } } extern struct in_ifaddr *ifptoia(); struct in_ifaddr *ip_rtaddr(); /* * Do option processing on a datagram, * possibly discarding it if bad options are encountered, * or forwarding it if source-routed. * Returns 1 if packet has been forwarded/freed, * 0 if the packet should be processed further. */ ip_dooptions(m) struct mbuf *m; { register struct ip *ip = mtod(m, struct ip *); register u_char *cp; register struct ip_timestamp *ipt; register struct in_ifaddr *ia; int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; struct in_addr *sin; n_time ntime; cp = (u_char *)(ip + 1); cnt = (ip->ip_hl << 2) - sizeof (struct ip); for (; cnt > 0; cnt -= optlen, cp += optlen) { opt = cp[IPOPT_OPTVAL]; if (opt == IPOPT_EOL) break; if (opt == IPOPT_NOP) optlen = 1; else { optlen = cp[IPOPT_OLEN]; if (optlen <= 0 || optlen > cnt) { code = &cp[IPOPT_OLEN] - (u_char *)ip; goto bad; } } switch (opt) { default: break; /* * Source routing with record. * Find interface with current destination address. * If none on this machine then drop if strictly routed, * or do nothing if loosely routed. * Record interface address and bring up next address * component. If strictly routed make sure next * address is on directly accessible net. */ case IPOPT_LSRR: case IPOPT_SSRR: if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } ipaddr.sin_addr = ip->ip_dst; ia = (struct in_ifaddr *) ifa_ifwithaddr((struct sockaddr *)&ipaddr); if (ia == 0) { if (opt == IPOPT_SSRR) { type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; goto bad; } /* * Loose routing, and not at next destination * yet; nothing to do except forward. */ break; } off--; /* 0 origin */ if (off > optlen - sizeof(struct in_addr)) { /* * End of source route. Should be for us. */ save_rte(cp, ip->ip_src); break; } /* * locate outgoing interface */ bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr, sizeof(ipaddr.sin_addr)); if (opt == IPOPT_SSRR) { #define INA struct in_ifaddr * #define SA struct sockaddr * if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0) ia = in_iaonnetof(in_netof(ipaddr.sin_addr)); } else ia = ip_rtaddr(ipaddr.sin_addr); if (ia == 0) { type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; goto bad; } ip->ip_dst = ipaddr.sin_addr; bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), (caddr_t)(cp + off), sizeof(struct in_addr)); cp[IPOPT_OFFSET] += sizeof(struct in_addr); forward = 1; break; case IPOPT_RR: if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } /* * If no space remains, ignore. */ off--; /* 0 origin */ if (off > optlen - sizeof(struct in_addr)) break; bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr, sizeof(ipaddr.sin_addr)); /* * locate outgoing interface; if we're the destination, * use the incoming interface (should be same). */ if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 && (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) { type = ICMP_UNREACH; code = ICMP_UNREACH_HOST; goto bad; } bcopy((caddr_t)&(IA_SIN(ia)->sin_addr), (caddr_t)(cp + off), sizeof(struct in_addr)); cp[IPOPT_OFFSET] += sizeof(struct in_addr); break; case IPOPT_TS: code = cp - (u_char *)ip; ipt = (struct ip_timestamp *)cp; if (ipt->ipt_len < 5) goto bad; if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) { if (++ipt->ipt_oflw == 0) goto bad; break; } sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1); switch (ipt->ipt_flg) { case IPOPT_TS_TSONLY: break; case IPOPT_TS_TSANDADDR: if (ipt->ipt_ptr + sizeof(n_time) + sizeof(struct in_addr) > ipt->ipt_len) goto bad; ia = ifptoia(m->m_pkthdr.rcvif); bcopy((caddr_t)&IA_SIN(ia)->sin_addr, (caddr_t)sin, sizeof(struct in_addr)); ipt->ipt_ptr += sizeof(struct in_addr); break; case IPOPT_TS_PRESPEC: if (ipt->ipt_ptr + sizeof(n_time) + sizeof(struct in_addr) > ipt->ipt_len) goto bad; bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr, sizeof(struct in_addr)); if (ifa_ifwithaddr((SA)&ipaddr) == 0) continue; ipt->ipt_ptr += sizeof(struct in_addr); break; default: goto bad; } ntime = iptime(); bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1, sizeof(n_time)); ipt->ipt_ptr += sizeof(n_time); } } if (forward) { ip_forward(m, 1); return (1); } else return (0); bad: icmp_error(m, type, code); return (1); } /* * Given address of next destination (final or next hop), * return internet address info of interface to be used to get there. */ struct in_ifaddr * ip_rtaddr(dst) struct in_addr dst; { register struct sockaddr_in *sin; sin = (struct sockaddr_in *) &ipforward_rt.ro_dst; if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) { if (ipforward_rt.ro_rt) { RTFREE(ipforward_rt.ro_rt); ipforward_rt.ro_rt = 0; } sin->sin_family = AF_INET; sin->sin_len = sizeof(*sin); sin->sin_addr = dst; rtalloc(&ipforward_rt); } if (ipforward_rt.ro_rt == 0) return ((struct in_ifaddr *)0); return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa); } /* * Save incoming source route for use in replies, * to be picked up later by ip_srcroute if the receiver is interested. */ save_rte(option, dst) u_char *option; struct in_addr dst; { unsigned olen; olen = option[IPOPT_OLEN]; #ifdef DIAGNOSTIC if (ipprintfs) printf("save_rte: olen %d\n", olen); #endif if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst))) return; bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen); ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); ip_srcrt.dst = dst; } /* * Retrieve incoming source route for use in replies, * in the same form used by setsockopt. * The first hop is placed before the options, will be removed later. */ struct mbuf * ip_srcroute() { register struct in_addr *p, *q; register struct mbuf *m; if (ip_nhops == 0) return ((struct mbuf *)0); m = m_get(M_DONTWAIT, MT_SOOPTS); if (m == 0) return ((struct mbuf *)0); #define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt)) /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) + OPTSIZ; #ifdef DIAGNOSTIC if (ipprintfs) printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len); #endif /* * First save first hop for return route */ p = &ip_srcrt.route[ip_nhops - 1]; *(mtod(m, struct in_addr *)) = *p--; #ifdef DIAGNOSTIC if (ipprintfs) printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr)); #endif /* * Copy option fields and padding (nop) to mbuf. */ ip_srcrt.nop = IPOPT_NOP; ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; bcopy((caddr_t)&ip_srcrt.nop, mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ); q = (struct in_addr *)(mtod(m, caddr_t) + sizeof(struct in_addr) + OPTSIZ); #undef OPTSIZ /* * Record return path as an IP source route, * reversing the path (pointers are now aligned). */ while (p >= ip_srcrt.route) { #ifdef DIAGNOSTIC if (ipprintfs) printf(" %lx", ntohl(q->s_addr)); #endif *q++ = *p--; } /* * Last hop goes to final destination. */ *q = ip_srcrt.dst; #ifdef DIAGNOSTIC if (ipprintfs) printf(" %lx\n", ntohl(q->s_addr)); #endif return (m); } /* * Strip out IP options, at higher * level protocol in the kernel. * Second argument is buffer to which options * will be moved, and return value is their length. * XXX should be deleted; last arg currently ignored. */ ip_stripoptions(m, mopt) register struct mbuf *m; struct mbuf *mopt; { register int i; struct ip *ip = mtod(m, struct ip *); register caddr_t opts; int olen; olen = (ip->ip_hl<<2) - sizeof (struct ip); opts = (caddr_t)(ip + 1); i = m->m_len - (sizeof (struct ip) + olen); bcopy(opts + olen, opts, (unsigned)i); m->m_len -= olen; if (m->m_flags & M_PKTHDR) m->m_pkthdr.len -= olen; ip->ip_hl = sizeof(struct ip) >> 2; } u_char inetctlerrmap[PRC_NCMDS] = { 0, 0, 0, 0, 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, EMSGSIZE, EHOSTUNREACH, 0, 0, 0, 0, 0, 0, ENOPROTOOPT }; /* * Forward a packet. If some error occurs return the sender * an icmp packet. Note we can't always generate a meaningful * icmp message because icmp doesn't have a large enough repertoire * of codes and types. * * If not forwarding, just drop the packet. This could be confusing * if ipforwarding was zero but some routing protocol was advancing * us as a gateway to somewhere. However, we must let the routing * protocol deal with that. * * The srcrt parameter indicates whether the packet is being forwarded * via a source route. */ ip_forward(m, srcrt) struct mbuf *m; int srcrt; { register struct ip *ip = mtod(m, struct ip *); register struct sockaddr_in *sin; register struct rtentry *rt; int error, type = 0, code; struct mbuf *mcopy; struct in_addr dest; dest.s_addr = 0; #ifdef DIAGNOSTIC if (ipprintfs) printf("forward: src %x dst %x ttl %x\n", ip->ip_src, ip->ip_dst, ip->ip_ttl); #endif if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) { ipstat.ips_cantforward++; m_freem(m); return; } HTONS(ip->ip_id); if (ip->ip_ttl <= IPTTLDEC) { icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest); return; } ip->ip_ttl -= IPTTLDEC; sin = (struct sockaddr_in *)&ipforward_rt.ro_dst; if ((rt = ipforward_rt.ro_rt) == 0 || ip->ip_dst.s_addr != sin->sin_addr.s_addr) { if (ipforward_rt.ro_rt) { RTFREE(ipforward_rt.ro_rt); ipforward_rt.ro_rt = 0; } sin->sin_family = AF_INET; sin->sin_len = sizeof(*sin); sin->sin_addr = ip->ip_dst; rtalloc(&ipforward_rt); if (ipforward_rt.ro_rt == 0) { icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest); return; } rt = ipforward_rt.ro_rt; } /* * Save at most 64 bytes of the packet in case * we need to generate an ICMP message to the src. */ mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64)); #ifdef GATEWAY ip_ifmatrix[rt->rt_ifp->if_index + if_index * m->m_pkthdr.rcvif->if_index]++; #endif /* * If forwarding packet using same interface that it came in on, * perhaps should send a redirect to sender to shortcut a hop. * Only send redirect if source is sending directly to us, * and if packet was not source routed (or has any options). * Also, don't send redirect if forwarding using a default route * or a route modified by a redirect. */ #define satosin(sa) ((struct sockaddr_in *)(sa)) if (rt->rt_ifp == m->m_pkthdr.rcvif && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && satosin(rt_key(rt))->sin_addr.s_addr != 0 && ipsendredirects && !srcrt) { struct in_ifaddr *ia; u_long src = ntohl(ip->ip_src.s_addr); u_long dst = ntohl(ip->ip_dst.s_addr); if ((ia = ifptoia(m->m_pkthdr.rcvif)) && (src & ia->ia_subnetmask) == ia->ia_subnet) { if (rt->rt_flags & RTF_GATEWAY) dest = satosin(rt->rt_gateway)->sin_addr; else dest = ip->ip_dst; /* * If the destination is reached by a route to host, * is on a subnet of a local net, or is directly * on the attached net (!), use host redirect. * (We may be the correct first hop for other subnets.) */ #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) type = ICMP_REDIRECT; if ((rt->rt_flags & RTF_HOST) || (rt->rt_flags & RTF_GATEWAY) == 0) code = ICMP_REDIRECT_HOST; else if (RTA(rt)->ia_subnetmask != RTA(rt)->ia_netmask && (dst & RTA(rt)->ia_netmask) == RTA(rt)->ia_net) code = ICMP_REDIRECT_HOST; else code = ICMP_REDIRECT_NET; #ifdef DIAGNOSTIC if (ipprintfs) printf("redirect (%d) to %x\n", code, dest.s_addr); #endif } } error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING); if (error) ipstat.ips_cantforward++; else { ipstat.ips_forward++; if (type) ipstat.ips_redirectsent++; else { if (mcopy) m_freem(mcopy); return; } } if (mcopy == NULL) return; switch (error) { case 0: /* forwarded, but need redirect */ /* type, code set above */ break; case ENETUNREACH: /* shouldn't happen, checked above */ case EHOSTUNREACH: case ENETDOWN: case EHOSTDOWN: default: type = ICMP_UNREACH; code = ICMP_UNREACH_HOST; break; case EMSGSIZE: type = ICMP_UNREACH; code = ICMP_UNREACH_NEEDFRAG; ipstat.ips_cantfrag++; break; case ENOBUFS: type = ICMP_SOURCEQUENCH; code = 0; break; } icmp_error(mcopy, type, code, dest); }