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Annotation of src/sys/netinet/ip_input.c, Revision 1.45

1.45    ! mrg         1: /*     $NetBSD: ip_input.c,v 1.44 1997/01/11 05:21:10 thorpej Exp $    */
1.14      cgd         2:
1.1       cgd         3: /*
1.13      mycroft     4:  * Copyright (c) 1982, 1986, 1988, 1993
                      5:  *     The Regents of the University of California.  All rights reserved.
1.1       cgd         6:  *
                      7:  * Redistribution and use in source and binary forms, with or without
                      8:  * modification, are permitted provided that the following conditions
                      9:  * are met:
                     10:  * 1. Redistributions of source code must retain the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer.
                     12:  * 2. Redistributions in binary form must reproduce the above copyright
                     13:  *    notice, this list of conditions and the following disclaimer in the
                     14:  *    documentation and/or other materials provided with the distribution.
                     15:  * 3. All advertising materials mentioning features or use of this software
                     16:  *    must display the following acknowledgement:
                     17:  *     This product includes software developed by the University of
                     18:  *     California, Berkeley and its contributors.
                     19:  * 4. Neither the name of the University nor the names of its contributors
                     20:  *    may be used to endorse or promote products derived from this software
                     21:  *    without specific prior written permission.
                     22:  *
                     23:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     24:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     25:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     26:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     27:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     28:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     29:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     30:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     31:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     32:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     33:  * SUCH DAMAGE.
                     34:  *
1.14      cgd        35:  *     @(#)ip_input.c  8.2 (Berkeley) 1/4/94
1.1       cgd        36:  */
                     37:
1.5       mycroft    38: #include <sys/param.h>
                     39: #include <sys/systm.h>
                     40: #include <sys/malloc.h>
                     41: #include <sys/mbuf.h>
                     42: #include <sys/domain.h>
                     43: #include <sys/protosw.h>
                     44: #include <sys/socket.h>
1.44      thorpej    45: #include <sys/socketvar.h>
1.5       mycroft    46: #include <sys/errno.h>
                     47: #include <sys/time.h>
                     48: #include <sys/kernel.h>
1.28      christos   49: #include <sys/proc.h>
                     50:
                     51: #include <vm/vm.h>
                     52: #include <sys/sysctl.h>
1.1       cgd        53:
1.5       mycroft    54: #include <net/if.h>
1.44      thorpej    55: #include <net/if_dl.h>
1.5       mycroft    56: #include <net/route.h>
1.45    ! mrg        57: #include <net/pfil.h>
1.1       cgd        58:
1.5       mycroft    59: #include <netinet/in.h>
                     60: #include <netinet/in_systm.h>
                     61: #include <netinet/ip.h>
                     62: #include <netinet/in_pcb.h>
                     63: #include <netinet/in_var.h>
                     64: #include <netinet/ip_var.h>
                     65: #include <netinet/ip_icmp.h>
1.36      mrg        66:
1.44      thorpej    67: /* XXX should really put this in libkern.h */
                     68: #define        offsetof(type, member)  ((size_t)(&((type *)0)->member))
                     69:
1.1       cgd        70: #ifndef        IPFORWARDING
                     71: #ifdef GATEWAY
                     72: #define        IPFORWARDING    1       /* forward IP packets not for us */
                     73: #else /* GATEWAY */
                     74: #define        IPFORWARDING    0       /* don't forward IP packets not for us */
                     75: #endif /* GATEWAY */
                     76: #endif /* IPFORWARDING */
                     77: #ifndef        IPSENDREDIRECTS
                     78: #define        IPSENDREDIRECTS 1
                     79: #endif
1.26      thorpej    80: #ifndef IPFORWSRCRT
                     81: #define        IPFORWSRCRT     1       /* allow source-routed packets */
                     82: #endif
1.27      thorpej    83: /*
                     84:  * Note: DIRECTED_BROADCAST is handled this way so that previous
                     85:  * configuration using this option will Just Work.
                     86:  */
                     87: #ifndef IPDIRECTEDBCAST
                     88: #ifdef DIRECTED_BROADCAST
                     89: #define IPDIRECTEDBCAST        1
                     90: #else
                     91: #define        IPDIRECTEDBCAST 0
                     92: #endif /* DIRECTED_BROADCAST */
                     93: #endif /* IPDIRECTEDBCAST */
1.1       cgd        94: int    ipforwarding = IPFORWARDING;
                     95: int    ipsendredirects = IPSENDREDIRECTS;
1.13      mycroft    96: int    ip_defttl = IPDEFTTL;
1.26      thorpej    97: int    ip_forwsrcrt = IPFORWSRCRT;
1.27      thorpej    98: int    ip_directedbcast = IPDIRECTEDBCAST;
1.1       cgd        99: #ifdef DIAGNOSTIC
                    100: int    ipprintfs = 0;
                    101: #endif
                    102:
                    103: extern struct domain inetdomain;
                    104: extern struct protosw inetsw[];
                    105: u_char ip_protox[IPPROTO_MAX];
                    106: int    ipqmaxlen = IFQ_MAXLEN;
1.22      mycroft   107: struct in_ifaddrhead in_ifaddr;
1.13      mycroft   108: struct ifqueue ipintrq;
1.1       cgd       109:
                    110: /*
                    111:  * We need to save the IP options in case a protocol wants to respond
                    112:  * to an incoming packet over the same route if the packet got here
                    113:  * using IP source routing.  This allows connection establishment and
                    114:  * maintenance when the remote end is on a network that is not known
                    115:  * to us.
                    116:  */
                    117: int    ip_nhops = 0;
                    118: static struct ip_srcrt {
                    119:        struct  in_addr dst;                    /* final destination */
                    120:        char    nop;                            /* one NOP to align */
                    121:        char    srcopt[IPOPT_OFFSET + 1];       /* OPTVAL, OLEN and OFFSET */
                    122:        struct  in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
                    123: } ip_srcrt;
                    124:
1.13      mycroft   125: static void save_rte __P((u_char *, struct in_addr));
1.35      mycroft   126:
1.1       cgd       127: /*
                    128:  * IP initialization: fill in IP protocol switch table.
                    129:  * All protocols not implemented in kernel go to raw IP protocol handler.
                    130:  */
1.8       mycroft   131: void
1.1       cgd       132: ip_init()
                    133: {
                    134:        register struct protosw *pr;
                    135:        register int i;
                    136:
                    137:        pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
                    138:        if (pr == 0)
                    139:                panic("ip_init");
                    140:        for (i = 0; i < IPPROTO_MAX; i++)
                    141:                ip_protox[i] = pr - inetsw;
                    142:        for (pr = inetdomain.dom_protosw;
                    143:            pr < inetdomain.dom_protoswNPROTOSW; pr++)
                    144:                if (pr->pr_domain->dom_family == PF_INET &&
                    145:                    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
                    146:                        ip_protox[pr->pr_protocol] = pr - inetsw;
1.25      cgd       147:        LIST_INIT(&ipq);
1.1       cgd       148:        ip_id = time.tv_sec & 0xffff;
                    149:        ipintrq.ifq_maxlen = ipqmaxlen;
1.22      mycroft   150:        TAILQ_INIT(&in_ifaddr);
1.1       cgd       151: }
                    152:
                    153: struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
                    154: struct route ipforward_rt;
                    155:
                    156: /*
                    157:  * Ip input routine.  Checksum and byte swap header.  If fragmented
                    158:  * try to reassemble.  Process options.  Pass to next level.
                    159:  */
1.8       mycroft   160: void
1.1       cgd       161: ipintr()
                    162: {
1.33      mrg       163:        register struct ip *ip = NULL;
1.1       cgd       164:        register struct mbuf *m;
                    165:        register struct ipq *fp;
                    166:        register struct in_ifaddr *ia;
1.25      cgd       167:        struct ipqent *ipqe;
1.35      mycroft   168:        int hlen = 0, mff, len, s;
1.36      mrg       169: #ifdef PFIL_HOOKS
1.33      mrg       170:        struct packet_filter_hook *pfh;
                    171:        struct mbuf *m0;
1.43      mrg       172:        int rv;
1.36      mrg       173: #endif /* PFIL_HOOKS */
1.1       cgd       174:
                    175: next:
                    176:        /*
                    177:         * Get next datagram off input queue and get IP header
                    178:         * in first mbuf.
                    179:         */
                    180:        s = splimp();
                    181:        IF_DEQUEUE(&ipintrq, m);
                    182:        splx(s);
1.13      mycroft   183:        if (m == 0)
1.1       cgd       184:                return;
                    185: #ifdef DIAGNOSTIC
                    186:        if ((m->m_flags & M_PKTHDR) == 0)
                    187:                panic("ipintr no HDR");
                    188: #endif
                    189:        /*
                    190:         * If no IP addresses have been set yet but the interfaces
                    191:         * are receiving, can't do anything with incoming packets yet.
                    192:         */
1.22      mycroft   193:        if (in_ifaddr.tqh_first == 0)
1.1       cgd       194:                goto bad;
                    195:        ipstat.ips_total++;
                    196:        if (m->m_len < sizeof (struct ip) &&
                    197:            (m = m_pullup(m, sizeof (struct ip))) == 0) {
                    198:                ipstat.ips_toosmall++;
                    199:                goto next;
                    200:        }
                    201:        ip = mtod(m, struct ip *);
1.13      mycroft   202:        if (ip->ip_v != IPVERSION) {
                    203:                ipstat.ips_badvers++;
                    204:                goto bad;
                    205:        }
1.1       cgd       206:        hlen = ip->ip_hl << 2;
                    207:        if (hlen < sizeof(struct ip)) { /* minimum header length */
                    208:                ipstat.ips_badhlen++;
                    209:                goto bad;
                    210:        }
                    211:        if (hlen > m->m_len) {
                    212:                if ((m = m_pullup(m, hlen)) == 0) {
                    213:                        ipstat.ips_badhlen++;
                    214:                        goto next;
                    215:                }
                    216:                ip = mtod(m, struct ip *);
                    217:        }
1.28      christos  218:        if ((ip->ip_sum = in_cksum(m, hlen)) != 0) {
1.1       cgd       219:                ipstat.ips_badsum++;
                    220:                goto bad;
                    221:        }
                    222:
                    223:        /*
                    224:         * Convert fields to host representation.
                    225:         */
                    226:        NTOHS(ip->ip_len);
                    227:        NTOHS(ip->ip_id);
                    228:        NTOHS(ip->ip_off);
1.35      mycroft   229:        len = ip->ip_len;
1.1       cgd       230:
                    231:        /*
                    232:         * Check that the amount of data in the buffers
                    233:         * is as at least much as the IP header would have us expect.
                    234:         * Trim mbufs if longer than we expect.
                    235:         * Drop packet if shorter than we expect.
                    236:         */
1.35      mycroft   237:        if (m->m_pkthdr.len < len) {
1.1       cgd       238:                ipstat.ips_tooshort++;
                    239:                goto bad;
                    240:        }
1.35      mycroft   241:        if (m->m_pkthdr.len > len) {
1.1       cgd       242:                if (m->m_len == m->m_pkthdr.len) {
1.35      mycroft   243:                        m->m_len = len;
                    244:                        m->m_pkthdr.len = len;
1.1       cgd       245:                } else
1.35      mycroft   246:                        m_adj(m, len - m->m_pkthdr.len);
1.1       cgd       247:        }
                    248:
1.36      mrg       249: #ifdef PFIL_HOOKS
1.33      mrg       250:        /*
                    251:         * Run through list of hooks for input packets.
                    252:         */
                    253:        m0 = m;
                    254:        for (pfh = pfil_hook_get(PFIL_IN); pfh; pfh = pfh->pfil_link.le_next)
                    255:                if (pfh->pfil_func) {
1.43      mrg       256:                        rv = pfh->pfil_func(ip, hlen, m->m_pkthdr.rcvif, 0, &m0);
                    257:                        ip = mtod(m = m0, struct ip *);
                    258:                        if (rv)
1.40      veego     259:                                goto next;
1.33      mrg       260:                }
1.36      mrg       261: #endif /* PFIL_HOOKS */
1.33      mrg       262:
1.1       cgd       263:        /*
                    264:         * Process options and, if not destined for us,
                    265:         * ship it on.  ip_dooptions returns 1 when an
                    266:         * error was detected (causing an icmp message
                    267:         * to be sent and the original packet to be freed).
                    268:         */
                    269:        ip_nhops = 0;           /* for source routed packets */
                    270:        if (hlen > sizeof (struct ip) && ip_dooptions(m))
                    271:                goto next;
                    272:
                    273:        /*
                    274:         * Check our list of addresses, to see if the packet is for us.
                    275:         */
1.22      mycroft   276:        for (ia = in_ifaddr.tqh_first; ia; ia = ia->ia_list.tqe_next) {
1.35      mycroft   277:                if (in_hosteq(ip->ip_dst, ia->ia_addr.sin_addr))
1.1       cgd       278:                        goto ours;
1.27      thorpej   279:                if (((ip_directedbcast == 0) || (ip_directedbcast &&
                    280:                    ia->ia_ifp == m->m_pkthdr.rcvif)) &&
1.1       cgd       281:                    (ia->ia_ifp->if_flags & IFF_BROADCAST)) {
1.35      mycroft   282:                        if (in_hosteq(ip->ip_dst, ia->ia_broadaddr.sin_addr) ||
                    283:                            in_hosteq(ip->ip_dst, ia->ia_netbroadcast) ||
1.20      mycroft   284:                            /*
                    285:                             * Look for all-0's host part (old broadcast addr),
                    286:                             * either for subnet or net.
                    287:                             */
                    288:                            ip->ip_dst.s_addr == ia->ia_subnet ||
1.18      mycroft   289:                            ip->ip_dst.s_addr == ia->ia_net)
1.1       cgd       290:                                goto ours;
                    291:                }
                    292:        }
1.18      mycroft   293:        if (IN_MULTICAST(ip->ip_dst.s_addr)) {
1.4       hpeyerl   294:                struct in_multi *inm;
                    295: #ifdef MROUTING
                    296:                extern struct socket *ip_mrouter;
1.10      brezak    297:
                    298:                if (m->m_flags & M_EXT) {
                    299:                        if ((m = m_pullup(m, hlen)) == 0) {
                    300:                                ipstat.ips_toosmall++;
                    301:                                goto next;
                    302:                        }
                    303:                        ip = mtod(m, struct ip *);
                    304:                }
1.4       hpeyerl   305:
                    306:                if (ip_mrouter) {
                    307:                        /*
                    308:                         * If we are acting as a multicast router, all
                    309:                         * incoming multicast packets are passed to the
                    310:                         * kernel-level multicast forwarding function.
                    311:                         * The packet is returned (relatively) intact; if
                    312:                         * ip_mforward() returns a non-zero value, the packet
                    313:                         * must be discarded, else it may be accepted below.
                    314:                         *
                    315:                         * (The IP ident field is put in the same byte order
                    316:                         * as expected when ip_mforward() is called from
                    317:                         * ip_output().)
                    318:                         */
                    319:                        ip->ip_id = htons(ip->ip_id);
1.13      mycroft   320:                        if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) {
                    321:                                ipstat.ips_cantforward++;
1.4       hpeyerl   322:                                m_freem(m);
                    323:                                goto next;
                    324:                        }
                    325:                        ip->ip_id = ntohs(ip->ip_id);
                    326:
                    327:                        /*
                    328:                         * The process-level routing demon needs to receive
                    329:                         * all multicast IGMP packets, whether or not this
                    330:                         * host belongs to their destination groups.
                    331:                         */
                    332:                        if (ip->ip_p == IPPROTO_IGMP)
                    333:                                goto ours;
1.13      mycroft   334:                        ipstat.ips_forward++;
1.4       hpeyerl   335:                }
                    336: #endif
                    337:                /*
                    338:                 * See if we belong to the destination multicast group on the
                    339:                 * arrival interface.
                    340:                 */
                    341:                IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
                    342:                if (inm == NULL) {
1.13      mycroft   343:                        ipstat.ips_cantforward++;
1.4       hpeyerl   344:                        m_freem(m);
                    345:                        goto next;
                    346:                }
                    347:                goto ours;
                    348:        }
1.19      mycroft   349:        if (ip->ip_dst.s_addr == INADDR_BROADCAST ||
1.35      mycroft   350:            in_nullhost(ip->ip_dst))
1.1       cgd       351:                goto ours;
                    352:
                    353:        /*
                    354:         * Not for us; forward if possible and desirable.
                    355:         */
                    356:        if (ipforwarding == 0) {
                    357:                ipstat.ips_cantforward++;
                    358:                m_freem(m);
                    359:        } else
                    360:                ip_forward(m, 0);
                    361:        goto next;
                    362:
                    363: ours:
                    364:        /*
                    365:         * If offset or IP_MF are set, must reassemble.
                    366:         * Otherwise, nothing need be done.
                    367:         * (We could look in the reassembly queue to see
                    368:         * if the packet was previously fragmented,
                    369:         * but it's not worth the time; just let them time out.)
                    370:         */
1.37      perry     371:        if (ip->ip_off & ~(IP_DF|IP_RF)) {
1.1       cgd       372:                if (m->m_flags & M_EXT) {               /* XXX */
                    373:                        if ((m = m_pullup(m, sizeof (struct ip))) == 0) {
                    374:                                ipstat.ips_toosmall++;
                    375:                                goto next;
                    376:                        }
                    377:                        ip = mtod(m, struct ip *);
                    378:                }
                    379:                /*
                    380:                 * Look for queue of fragments
                    381:                 * of this datagram.
                    382:                 */
1.25      cgd       383:                for (fp = ipq.lh_first; fp != NULL; fp = fp->ipq_q.le_next)
1.1       cgd       384:                        if (ip->ip_id == fp->ipq_id &&
1.35      mycroft   385:                            in_hosteq(ip->ip_src, fp->ipq_src) &&
                    386:                            in_hosteq(ip->ip_dst, fp->ipq_dst) &&
1.1       cgd       387:                            ip->ip_p == fp->ipq_p)
                    388:                                goto found;
                    389:                fp = 0;
                    390: found:
                    391:
                    392:                /*
                    393:                 * Adjust ip_len to not reflect header,
1.25      cgd       394:                 * set ipqe_mff if more fragments are expected,
1.1       cgd       395:                 * convert offset of this to bytes.
                    396:                 */
                    397:                ip->ip_len -= hlen;
1.25      cgd       398:                mff = (ip->ip_off & IP_MF) != 0;
                    399:                if (mff) {
1.16      cgd       400:                        /*
                    401:                         * Make sure that fragments have a data length
                    402:                         * that's a non-zero multiple of 8 bytes.
                    403:                         */
1.17      cgd       404:                        if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
1.16      cgd       405:                                ipstat.ips_badfrags++;
                    406:                                goto bad;
                    407:                        }
                    408:                }
1.1       cgd       409:                ip->ip_off <<= 3;
                    410:
                    411:                /*
                    412:                 * If datagram marked as having more fragments
                    413:                 * or if this is not the first fragment,
                    414:                 * attempt reassembly; if it succeeds, proceed.
                    415:                 */
1.25      cgd       416:                if (mff || ip->ip_off) {
1.1       cgd       417:                        ipstat.ips_fragments++;
1.25      cgd       418:                        MALLOC(ipqe, struct ipqent *, sizeof (struct ipqent),
                    419:                            M_IPQ, M_NOWAIT);
                    420:                        if (ipqe == NULL) {
                    421:                                ipstat.ips_rcvmemdrop++;
                    422:                                goto bad;
                    423:                        }
                    424:                        ipqe->ipqe_mff = mff;
                    425:                        ipqe->ipqe_ip = ip;
                    426:                        ip = ip_reass(ipqe, fp);
1.1       cgd       427:                        if (ip == 0)
                    428:                                goto next;
1.13      mycroft   429:                        ipstat.ips_reassembled++;
1.1       cgd       430:                        m = dtom(ip);
                    431:                } else
                    432:                        if (fp)
                    433:                                ip_freef(fp);
                    434:        } else
                    435:                ip->ip_len -= hlen;
                    436:
                    437:        /*
                    438:         * Switch out to protocol's input routine.
                    439:         */
                    440:        ipstat.ips_delivered++;
                    441:        (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
                    442:        goto next;
                    443: bad:
                    444:        m_freem(m);
                    445:        goto next;
                    446: }
                    447:
                    448: /*
                    449:  * Take incoming datagram fragment and try to
                    450:  * reassemble it into whole datagram.  If a chain for
                    451:  * reassembly of this datagram already exists, then it
                    452:  * is given as fp; otherwise have to make a chain.
                    453:  */
                    454: struct ip *
1.25      cgd       455: ip_reass(ipqe, fp)
                    456:        register struct ipqent *ipqe;
1.1       cgd       457:        register struct ipq *fp;
                    458: {
1.25      cgd       459:        register struct mbuf *m = dtom(ipqe->ipqe_ip);
                    460:        register struct ipqent *nq, *p, *q;
                    461:        struct ip *ip;
1.1       cgd       462:        struct mbuf *t;
1.25      cgd       463:        int hlen = ipqe->ipqe_ip->ip_hl << 2;
1.1       cgd       464:        int i, next;
                    465:
                    466:        /*
                    467:         * Presence of header sizes in mbufs
                    468:         * would confuse code below.
                    469:         */
                    470:        m->m_data += hlen;
                    471:        m->m_len -= hlen;
                    472:
                    473:        /*
                    474:         * If first fragment to arrive, create a reassembly queue.
                    475:         */
                    476:        if (fp == 0) {
                    477:                if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
                    478:                        goto dropfrag;
                    479:                fp = mtod(t, struct ipq *);
1.25      cgd       480:                LIST_INSERT_HEAD(&ipq, fp, ipq_q);
1.1       cgd       481:                fp->ipq_ttl = IPFRAGTTL;
1.25      cgd       482:                fp->ipq_p = ipqe->ipqe_ip->ip_p;
                    483:                fp->ipq_id = ipqe->ipqe_ip->ip_id;
                    484:                LIST_INIT(&fp->ipq_fragq);
                    485:                fp->ipq_src = ipqe->ipqe_ip->ip_src;
                    486:                fp->ipq_dst = ipqe->ipqe_ip->ip_dst;
                    487:                p = NULL;
1.1       cgd       488:                goto insert;
                    489:        }
                    490:
                    491:        /*
                    492:         * Find a segment which begins after this one does.
                    493:         */
1.25      cgd       494:        for (p = NULL, q = fp->ipq_fragq.lh_first; q != NULL;
                    495:            p = q, q = q->ipqe_q.le_next)
                    496:                if (q->ipqe_ip->ip_off > ipqe->ipqe_ip->ip_off)
1.1       cgd       497:                        break;
                    498:
                    499:        /*
                    500:         * If there is a preceding segment, it may provide some of
                    501:         * our data already.  If so, drop the data from the incoming
                    502:         * segment.  If it provides all of our data, drop us.
                    503:         */
1.25      cgd       504:        if (p != NULL) {
                    505:                i = p->ipqe_ip->ip_off + p->ipqe_ip->ip_len -
                    506:                    ipqe->ipqe_ip->ip_off;
1.1       cgd       507:                if (i > 0) {
1.25      cgd       508:                        if (i >= ipqe->ipqe_ip->ip_len)
1.1       cgd       509:                                goto dropfrag;
1.25      cgd       510:                        m_adj(dtom(ipqe->ipqe_ip), i);
                    511:                        ipqe->ipqe_ip->ip_off += i;
                    512:                        ipqe->ipqe_ip->ip_len -= i;
1.1       cgd       513:                }
                    514:        }
                    515:
                    516:        /*
                    517:         * While we overlap succeeding segments trim them or,
                    518:         * if they are completely covered, dequeue them.
                    519:         */
1.25      cgd       520:        for (; q != NULL && ipqe->ipqe_ip->ip_off + ipqe->ipqe_ip->ip_len >
                    521:            q->ipqe_ip->ip_off; q = nq) {
                    522:                i = (ipqe->ipqe_ip->ip_off + ipqe->ipqe_ip->ip_len) -
                    523:                    q->ipqe_ip->ip_off;
                    524:                if (i < q->ipqe_ip->ip_len) {
                    525:                        q->ipqe_ip->ip_len -= i;
                    526:                        q->ipqe_ip->ip_off += i;
                    527:                        m_adj(dtom(q->ipqe_ip), i);
1.1       cgd       528:                        break;
                    529:                }
1.25      cgd       530:                nq = q->ipqe_q.le_next;
                    531:                m_freem(dtom(q->ipqe_ip));
                    532:                LIST_REMOVE(q, ipqe_q);
                    533:                FREE(q, M_IPQ);
1.1       cgd       534:        }
                    535:
                    536: insert:
                    537:        /*
                    538:         * Stick new segment in its place;
                    539:         * check for complete reassembly.
                    540:         */
1.25      cgd       541:        if (p == NULL) {
                    542:                LIST_INSERT_HEAD(&fp->ipq_fragq, ipqe, ipqe_q);
                    543:        } else {
                    544:                LIST_INSERT_AFTER(p, ipqe, ipqe_q);
                    545:        }
1.1       cgd       546:        next = 0;
1.25      cgd       547:        for (p = NULL, q = fp->ipq_fragq.lh_first; q != NULL;
                    548:            p = q, q = q->ipqe_q.le_next) {
                    549:                if (q->ipqe_ip->ip_off != next)
1.1       cgd       550:                        return (0);
1.25      cgd       551:                next += q->ipqe_ip->ip_len;
1.1       cgd       552:        }
1.25      cgd       553:        if (p->ipqe_mff)
1.1       cgd       554:                return (0);
                    555:
                    556:        /*
1.41      thorpej   557:         * Reassembly is complete.  Check for a bogus message size and
                    558:         * concatenate fragments.
1.1       cgd       559:         */
1.25      cgd       560:        q = fp->ipq_fragq.lh_first;
                    561:        ip = q->ipqe_ip;
1.41      thorpej   562:        if ((next + (ip->ip_hl << 2)) > IP_MAXPACKET) {
                    563:                ipstat.ips_toolong++;
                    564:                ip_freef(fp);
                    565:                return (0);
                    566:        }
1.25      cgd       567:        m = dtom(q->ipqe_ip);
1.1       cgd       568:        t = m->m_next;
                    569:        m->m_next = 0;
                    570:        m_cat(m, t);
1.25      cgd       571:        nq = q->ipqe_q.le_next;
                    572:        FREE(q, M_IPQ);
                    573:        for (q = nq; q != NULL; q = nq) {
                    574:                t = dtom(q->ipqe_ip);
                    575:                nq = q->ipqe_q.le_next;
                    576:                FREE(q, M_IPQ);
1.1       cgd       577:                m_cat(m, t);
                    578:        }
                    579:
                    580:        /*
                    581:         * Create header for new ip packet by
                    582:         * modifying header of first packet;
                    583:         * dequeue and discard fragment reassembly header.
                    584:         * Make header visible.
                    585:         */
                    586:        ip->ip_len = next;
1.25      cgd       587:        ip->ip_src = fp->ipq_src;
                    588:        ip->ip_dst = fp->ipq_dst;
                    589:        LIST_REMOVE(fp, ipq_q);
1.1       cgd       590:        (void) m_free(dtom(fp));
                    591:        m->m_len += (ip->ip_hl << 2);
                    592:        m->m_data -= (ip->ip_hl << 2);
                    593:        /* some debugging cruft by sklower, below, will go away soon */
                    594:        if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
                    595:                register int plen = 0;
                    596:                for (t = m; m; m = m->m_next)
                    597:                        plen += m->m_len;
                    598:                t->m_pkthdr.len = plen;
                    599:        }
1.25      cgd       600:        return (ip);
1.1       cgd       601:
                    602: dropfrag:
                    603:        ipstat.ips_fragdropped++;
                    604:        m_freem(m);
1.25      cgd       605:        FREE(ipqe, M_IPQ);
1.1       cgd       606:        return (0);
                    607: }
                    608:
                    609: /*
                    610:  * Free a fragment reassembly header and all
                    611:  * associated datagrams.
                    612:  */
1.8       mycroft   613: void
1.1       cgd       614: ip_freef(fp)
                    615:        struct ipq *fp;
                    616: {
1.25      cgd       617:        register struct ipqent *q, *p;
1.1       cgd       618:
1.25      cgd       619:        for (q = fp->ipq_fragq.lh_first; q != NULL; q = p) {
                    620:                p = q->ipqe_q.le_next;
                    621:                m_freem(dtom(q->ipqe_ip));
                    622:                LIST_REMOVE(q, ipqe_q);
                    623:                FREE(q, M_IPQ);
1.1       cgd       624:        }
1.25      cgd       625:        LIST_REMOVE(fp, ipq_q);
1.1       cgd       626:        (void) m_free(dtom(fp));
                    627: }
                    628:
                    629: /*
                    630:  * IP timer processing;
                    631:  * if a timer expires on a reassembly
                    632:  * queue, discard it.
                    633:  */
1.8       mycroft   634: void
1.1       cgd       635: ip_slowtimo()
                    636: {
1.25      cgd       637:        register struct ipq *fp, *nfp;
1.24      mycroft   638:        int s = splsoftnet();
1.1       cgd       639:
1.25      cgd       640:        for (fp = ipq.lh_first; fp != NULL; fp = nfp) {
                    641:                nfp = fp->ipq_q.le_next;
                    642:                if (--fp->ipq_ttl == 0) {
1.1       cgd       643:                        ipstat.ips_fragtimeout++;
1.25      cgd       644:                        ip_freef(fp);
1.1       cgd       645:                }
                    646:        }
                    647:        splx(s);
                    648: }
                    649:
                    650: /*
                    651:  * Drain off all datagram fragments.
                    652:  */
1.8       mycroft   653: void
1.1       cgd       654: ip_drain()
                    655: {
                    656:
1.25      cgd       657:        while (ipq.lh_first != NULL) {
1.1       cgd       658:                ipstat.ips_fragdropped++;
1.25      cgd       659:                ip_freef(ipq.lh_first);
1.1       cgd       660:        }
                    661: }
                    662:
                    663: /*
                    664:  * Do option processing on a datagram,
                    665:  * possibly discarding it if bad options are encountered,
                    666:  * or forwarding it if source-routed.
                    667:  * Returns 1 if packet has been forwarded/freed,
                    668:  * 0 if the packet should be processed further.
                    669:  */
1.8       mycroft   670: int
1.1       cgd       671: ip_dooptions(m)
                    672:        struct mbuf *m;
                    673: {
                    674:        register struct ip *ip = mtod(m, struct ip *);
                    675:        register u_char *cp;
                    676:        register struct ip_timestamp *ipt;
                    677:        register struct in_ifaddr *ia;
                    678:        int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
1.13      mycroft   679:        struct in_addr *sin, dst;
1.1       cgd       680:        n_time ntime;
                    681:
1.13      mycroft   682:        dst = ip->ip_dst;
1.1       cgd       683:        cp = (u_char *)(ip + 1);
                    684:        cnt = (ip->ip_hl << 2) - sizeof (struct ip);
                    685:        for (; cnt > 0; cnt -= optlen, cp += optlen) {
                    686:                opt = cp[IPOPT_OPTVAL];
                    687:                if (opt == IPOPT_EOL)
                    688:                        break;
                    689:                if (opt == IPOPT_NOP)
                    690:                        optlen = 1;
                    691:                else {
                    692:                        optlen = cp[IPOPT_OLEN];
                    693:                        if (optlen <= 0 || optlen > cnt) {
                    694:                                code = &cp[IPOPT_OLEN] - (u_char *)ip;
                    695:                                goto bad;
                    696:                        }
                    697:                }
                    698:                switch (opt) {
                    699:
                    700:                default:
                    701:                        break;
                    702:
                    703:                /*
                    704:                 * Source routing with record.
                    705:                 * Find interface with current destination address.
                    706:                 * If none on this machine then drop if strictly routed,
                    707:                 * or do nothing if loosely routed.
                    708:                 * Record interface address and bring up next address
                    709:                 * component.  If strictly routed make sure next
                    710:                 * address is on directly accessible net.
                    711:                 */
                    712:                case IPOPT_LSRR:
                    713:                case IPOPT_SSRR:
                    714:                        if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
                    715:                                code = &cp[IPOPT_OFFSET] - (u_char *)ip;
                    716:                                goto bad;
                    717:                        }
                    718:                        ipaddr.sin_addr = ip->ip_dst;
1.19      mycroft   719:                        ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)));
1.1       cgd       720:                        if (ia == 0) {
                    721:                                if (opt == IPOPT_SSRR) {
                    722:                                        type = ICMP_UNREACH;
                    723:                                        code = ICMP_UNREACH_SRCFAIL;
                    724:                                        goto bad;
                    725:                                }
                    726:                                /*
                    727:                                 * Loose routing, and not at next destination
                    728:                                 * yet; nothing to do except forward.
                    729:                                 */
                    730:                                break;
                    731:                        }
                    732:                        off--;                  /* 0 origin */
                    733:                        if (off > optlen - sizeof(struct in_addr)) {
                    734:                                /*
                    735:                                 * End of source route.  Should be for us.
                    736:                                 */
                    737:                                save_rte(cp, ip->ip_src);
                    738:                                break;
                    739:                        }
                    740:                        /*
                    741:                         * locate outgoing interface
                    742:                         */
                    743:                        bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
                    744:                            sizeof(ipaddr.sin_addr));
                    745:                        if (opt == IPOPT_SSRR) {
                    746: #define        INA     struct in_ifaddr *
                    747: #define        SA      struct sockaddr *
1.29      mrg       748:                            ia = (INA)ifa_ifwithladdr((SA)&ipaddr);
1.1       cgd       749:                        } else
                    750:                                ia = ip_rtaddr(ipaddr.sin_addr);
                    751:                        if (ia == 0) {
                    752:                                type = ICMP_UNREACH;
                    753:                                code = ICMP_UNREACH_SRCFAIL;
                    754:                                goto bad;
                    755:                        }
                    756:                        ip->ip_dst = ipaddr.sin_addr;
1.20      mycroft   757:                        bcopy((caddr_t)&ia->ia_addr.sin_addr,
1.1       cgd       758:                            (caddr_t)(cp + off), sizeof(struct in_addr));
                    759:                        cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1.13      mycroft   760:                        /*
                    761:                         * Let ip_intr's mcast routing check handle mcast pkts
                    762:                         */
1.18      mycroft   763:                        forward = !IN_MULTICAST(ip->ip_dst.s_addr);
1.1       cgd       764:                        break;
                    765:
                    766:                case IPOPT_RR:
                    767:                        if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
                    768:                                code = &cp[IPOPT_OFFSET] - (u_char *)ip;
                    769:                                goto bad;
                    770:                        }
                    771:                        /*
                    772:                         * If no space remains, ignore.
                    773:                         */
                    774:                        off--;                  /* 0 origin */
                    775:                        if (off > optlen - sizeof(struct in_addr))
                    776:                                break;
                    777:                        bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
                    778:                            sizeof(ipaddr.sin_addr));
                    779:                        /*
                    780:                         * locate outgoing interface; if we're the destination,
                    781:                         * use the incoming interface (should be same).
                    782:                         */
                    783:                        if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
                    784:                            (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
                    785:                                type = ICMP_UNREACH;
                    786:                                code = ICMP_UNREACH_HOST;
                    787:                                goto bad;
                    788:                        }
1.20      mycroft   789:                        bcopy((caddr_t)&ia->ia_addr.sin_addr,
1.1       cgd       790:                            (caddr_t)(cp + off), sizeof(struct in_addr));
                    791:                        cp[IPOPT_OFFSET] += sizeof(struct in_addr);
                    792:                        break;
                    793:
                    794:                case IPOPT_TS:
                    795:                        code = cp - (u_char *)ip;
                    796:                        ipt = (struct ip_timestamp *)cp;
                    797:                        if (ipt->ipt_len < 5)
                    798:                                goto bad;
1.15      cgd       799:                        if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
1.1       cgd       800:                                if (++ipt->ipt_oflw == 0)
                    801:                                        goto bad;
                    802:                                break;
                    803:                        }
                    804:                        sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
                    805:                        switch (ipt->ipt_flg) {
                    806:
                    807:                        case IPOPT_TS_TSONLY:
                    808:                                break;
                    809:
                    810:                        case IPOPT_TS_TSANDADDR:
                    811:                                if (ipt->ipt_ptr + sizeof(n_time) +
                    812:                                    sizeof(struct in_addr) > ipt->ipt_len)
                    813:                                        goto bad;
1.13      mycroft   814:                                ipaddr.sin_addr = dst;
                    815:                                ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
                    816:                                                            m->m_pkthdr.rcvif);
                    817:                                if (ia == 0)
                    818:                                        continue;
1.20      mycroft   819:                                bcopy((caddr_t)&ia->ia_addr.sin_addr,
1.1       cgd       820:                                    (caddr_t)sin, sizeof(struct in_addr));
                    821:                                ipt->ipt_ptr += sizeof(struct in_addr);
                    822:                                break;
                    823:
                    824:                        case IPOPT_TS_PRESPEC:
                    825:                                if (ipt->ipt_ptr + sizeof(n_time) +
                    826:                                    sizeof(struct in_addr) > ipt->ipt_len)
                    827:                                        goto bad;
                    828:                                bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
                    829:                                    sizeof(struct in_addr));
                    830:                                if (ifa_ifwithaddr((SA)&ipaddr) == 0)
                    831:                                        continue;
                    832:                                ipt->ipt_ptr += sizeof(struct in_addr);
                    833:                                break;
                    834:
                    835:                        default:
                    836:                                goto bad;
                    837:                        }
                    838:                        ntime = iptime();
                    839:                        bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
                    840:                            sizeof(n_time));
                    841:                        ipt->ipt_ptr += sizeof(n_time);
                    842:                }
                    843:        }
                    844:        if (forward) {
1.26      thorpej   845:                if (ip_forwsrcrt == 0) {
                    846:                        type = ICMP_UNREACH;
                    847:                        code = ICMP_UNREACH_SRCFAIL;
                    848:                        goto bad;
                    849:                }
1.1       cgd       850:                ip_forward(m, 1);
                    851:                return (1);
1.13      mycroft   852:        }
                    853:        return (0);
1.1       cgd       854: bad:
1.13      mycroft   855:        ip->ip_len -= ip->ip_hl << 2;   /* XXX icmp_error adds in hdr length */
                    856:        icmp_error(m, type, code, 0, 0);
                    857:        ipstat.ips_badoptions++;
1.1       cgd       858:        return (1);
                    859: }
                    860:
                    861: /*
                    862:  * Given address of next destination (final or next hop),
                    863:  * return internet address info of interface to be used to get there.
                    864:  */
                    865: struct in_ifaddr *
                    866: ip_rtaddr(dst)
                    867:         struct in_addr dst;
                    868: {
                    869:        register struct sockaddr_in *sin;
                    870:
1.19      mycroft   871:        sin = satosin(&ipforward_rt.ro_dst);
1.1       cgd       872:
1.35      mycroft   873:        if (ipforward_rt.ro_rt == 0 || !in_hosteq(dst, sin->sin_addr)) {
1.1       cgd       874:                if (ipforward_rt.ro_rt) {
                    875:                        RTFREE(ipforward_rt.ro_rt);
                    876:                        ipforward_rt.ro_rt = 0;
                    877:                }
                    878:                sin->sin_family = AF_INET;
                    879:                sin->sin_len = sizeof(*sin);
                    880:                sin->sin_addr = dst;
                    881:
                    882:                rtalloc(&ipforward_rt);
                    883:        }
                    884:        if (ipforward_rt.ro_rt == 0)
                    885:                return ((struct in_ifaddr *)0);
1.19      mycroft   886:        return (ifatoia(ipforward_rt.ro_rt->rt_ifa));
1.1       cgd       887: }
                    888:
                    889: /*
                    890:  * Save incoming source route for use in replies,
                    891:  * to be picked up later by ip_srcroute if the receiver is interested.
                    892:  */
1.13      mycroft   893: void
1.1       cgd       894: save_rte(option, dst)
                    895:        u_char *option;
                    896:        struct in_addr dst;
                    897: {
                    898:        unsigned olen;
                    899:
                    900:        olen = option[IPOPT_OLEN];
                    901: #ifdef DIAGNOSTIC
                    902:        if (ipprintfs)
1.39      christos  903:                printf("save_rte: olen %d\n", olen);
1.1       cgd       904: #endif
                    905:        if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
                    906:                return;
                    907:        bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen);
                    908:        ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
                    909:        ip_srcrt.dst = dst;
                    910: }
                    911:
                    912: /*
                    913:  * Retrieve incoming source route for use in replies,
                    914:  * in the same form used by setsockopt.
                    915:  * The first hop is placed before the options, will be removed later.
                    916:  */
                    917: struct mbuf *
                    918: ip_srcroute()
                    919: {
                    920:        register struct in_addr *p, *q;
                    921:        register struct mbuf *m;
                    922:
                    923:        if (ip_nhops == 0)
                    924:                return ((struct mbuf *)0);
                    925:        m = m_get(M_DONTWAIT, MT_SOOPTS);
                    926:        if (m == 0)
                    927:                return ((struct mbuf *)0);
                    928:
1.13      mycroft   929: #define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
1.1       cgd       930:
                    931:        /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
                    932:        m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
                    933:            OPTSIZ;
                    934: #ifdef DIAGNOSTIC
                    935:        if (ipprintfs)
1.39      christos  936:                printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
1.1       cgd       937: #endif
                    938:
                    939:        /*
                    940:         * First save first hop for return route
                    941:         */
                    942:        p = &ip_srcrt.route[ip_nhops - 1];
                    943:        *(mtod(m, struct in_addr *)) = *p--;
                    944: #ifdef DIAGNOSTIC
                    945:        if (ipprintfs)
1.39      christos  946:                printf(" hops %x", ntohl(mtod(m, struct in_addr *)->s_addr));
1.1       cgd       947: #endif
                    948:
                    949:        /*
                    950:         * Copy option fields and padding (nop) to mbuf.
                    951:         */
                    952:        ip_srcrt.nop = IPOPT_NOP;
                    953:        ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
                    954:        bcopy((caddr_t)&ip_srcrt.nop,
                    955:            mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ);
                    956:        q = (struct in_addr *)(mtod(m, caddr_t) +
                    957:            sizeof(struct in_addr) + OPTSIZ);
                    958: #undef OPTSIZ
                    959:        /*
                    960:         * Record return path as an IP source route,
                    961:         * reversing the path (pointers are now aligned).
                    962:         */
                    963:        while (p >= ip_srcrt.route) {
                    964: #ifdef DIAGNOSTIC
                    965:                if (ipprintfs)
1.39      christos  966:                        printf(" %x", ntohl(q->s_addr));
1.1       cgd       967: #endif
                    968:                *q++ = *p--;
                    969:        }
                    970:        /*
                    971:         * Last hop goes to final destination.
                    972:         */
                    973:        *q = ip_srcrt.dst;
                    974: #ifdef DIAGNOSTIC
                    975:        if (ipprintfs)
1.39      christos  976:                printf(" %x\n", ntohl(q->s_addr));
1.1       cgd       977: #endif
                    978:        return (m);
                    979: }
                    980:
                    981: /*
                    982:  * Strip out IP options, at higher
                    983:  * level protocol in the kernel.
                    984:  * Second argument is buffer to which options
                    985:  * will be moved, and return value is their length.
                    986:  * XXX should be deleted; last arg currently ignored.
                    987:  */
1.8       mycroft   988: void
1.1       cgd       989: ip_stripoptions(m, mopt)
                    990:        register struct mbuf *m;
                    991:        struct mbuf *mopt;
                    992: {
                    993:        register int i;
                    994:        struct ip *ip = mtod(m, struct ip *);
                    995:        register caddr_t opts;
                    996:        int olen;
                    997:
                    998:        olen = (ip->ip_hl<<2) - sizeof (struct ip);
                    999:        opts = (caddr_t)(ip + 1);
                   1000:        i = m->m_len - (sizeof (struct ip) + olen);
                   1001:        bcopy(opts  + olen, opts, (unsigned)i);
                   1002:        m->m_len -= olen;
                   1003:        if (m->m_flags & M_PKTHDR)
                   1004:                m->m_pkthdr.len -= olen;
                   1005:        ip->ip_hl = sizeof(struct ip) >> 2;
                   1006: }
                   1007:
1.23      mycroft  1008: int inetctlerrmap[PRC_NCMDS] = {
1.1       cgd      1009:        0,              0,              0,              0,
                   1010:        0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
                   1011:        EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
                   1012:        EMSGSIZE,       EHOSTUNREACH,   0,              0,
                   1013:        0,              0,              0,              0,
                   1014:        ENOPROTOOPT
                   1015: };
                   1016:
                   1017: /*
                   1018:  * Forward a packet.  If some error occurs return the sender
                   1019:  * an icmp packet.  Note we can't always generate a meaningful
                   1020:  * icmp message because icmp doesn't have a large enough repertoire
                   1021:  * of codes and types.
                   1022:  *
                   1023:  * If not forwarding, just drop the packet.  This could be confusing
                   1024:  * if ipforwarding was zero but some routing protocol was advancing
                   1025:  * us as a gateway to somewhere.  However, we must let the routing
                   1026:  * protocol deal with that.
                   1027:  *
                   1028:  * The srcrt parameter indicates whether the packet is being forwarded
                   1029:  * via a source route.
                   1030:  */
1.13      mycroft  1031: void
1.1       cgd      1032: ip_forward(m, srcrt)
                   1033:        struct mbuf *m;
                   1034:        int srcrt;
                   1035: {
                   1036:        register struct ip *ip = mtod(m, struct ip *);
                   1037:        register struct sockaddr_in *sin;
                   1038:        register struct rtentry *rt;
1.28      christos 1039:        int error, type = 0, code = 0;
1.1       cgd      1040:        struct mbuf *mcopy;
1.13      mycroft  1041:        n_long dest;
                   1042:        struct ifnet *destifp;
1.1       cgd      1043:
1.13      mycroft  1044:        dest = 0;
1.1       cgd      1045: #ifdef DIAGNOSTIC
                   1046:        if (ipprintfs)
1.39      christos 1047:                printf("forward: src %x dst %x ttl %x\n",
1.35      mycroft  1048:                    ip->ip_src.s_addr, ip->ip_dst.s_addr, ip->ip_ttl);
1.1       cgd      1049: #endif
                   1050:        if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) {
                   1051:                ipstat.ips_cantforward++;
                   1052:                m_freem(m);
                   1053:                return;
                   1054:        }
                   1055:        HTONS(ip->ip_id);
                   1056:        if (ip->ip_ttl <= IPTTLDEC) {
1.13      mycroft  1057:                icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
1.1       cgd      1058:                return;
                   1059:        }
                   1060:        ip->ip_ttl -= IPTTLDEC;
                   1061:
1.19      mycroft  1062:        sin = satosin(&ipforward_rt.ro_dst);
1.1       cgd      1063:        if ((rt = ipforward_rt.ro_rt) == 0 ||
1.35      mycroft  1064:            !in_hosteq(ip->ip_dst, sin->sin_addr)) {
1.1       cgd      1065:                if (ipforward_rt.ro_rt) {
                   1066:                        RTFREE(ipforward_rt.ro_rt);
                   1067:                        ipforward_rt.ro_rt = 0;
                   1068:                }
                   1069:                sin->sin_family = AF_INET;
1.35      mycroft  1070:                sin->sin_len = sizeof(struct sockaddr_in);
1.1       cgd      1071:                sin->sin_addr = ip->ip_dst;
                   1072:
                   1073:                rtalloc(&ipforward_rt);
                   1074:                if (ipforward_rt.ro_rt == 0) {
1.13      mycroft  1075:                        icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
1.1       cgd      1076:                        return;
                   1077:                }
                   1078:                rt = ipforward_rt.ro_rt;
                   1079:        }
                   1080:
                   1081:        /*
1.34      mycroft  1082:         * Save at most 68 bytes of the packet in case
1.1       cgd      1083:         * we need to generate an ICMP message to the src.
                   1084:         */
1.34      mycroft  1085:        mcopy = m_copy(m, 0, imin((int)ip->ip_len, 68));
1.1       cgd      1086:
                   1087:        /*
                   1088:         * If forwarding packet using same interface that it came in on,
                   1089:         * perhaps should send a redirect to sender to shortcut a hop.
                   1090:         * Only send redirect if source is sending directly to us,
                   1091:         * and if packet was not source routed (or has any options).
                   1092:         * Also, don't send redirect if forwarding using a default route
                   1093:         * or a route modified by a redirect.
                   1094:         */
                   1095:        if (rt->rt_ifp == m->m_pkthdr.rcvif &&
                   1096:            (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1.35      mycroft  1097:            !in_nullhost(satosin(rt_key(rt))->sin_addr) &&
1.1       cgd      1098:            ipsendredirects && !srcrt) {
1.19      mycroft  1099:                if (rt->rt_ifa &&
                   1100:                    (ip->ip_src.s_addr & ifatoia(rt->rt_ifa)->ia_subnetmask) ==
                   1101:                    ifatoia(rt->rt_ifa)->ia_subnet) {
1.1       cgd      1102:                    if (rt->rt_flags & RTF_GATEWAY)
1.13      mycroft  1103:                        dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
1.1       cgd      1104:                    else
1.13      mycroft  1105:                        dest = ip->ip_dst.s_addr;
                   1106:                    /* Router requirements says to only send host redirects */
1.1       cgd      1107:                    type = ICMP_REDIRECT;
1.13      mycroft  1108:                    code = ICMP_REDIRECT_HOST;
1.1       cgd      1109: #ifdef DIAGNOSTIC
                   1110:                    if (ipprintfs)
1.39      christos 1111:                        printf("redirect (%d) to %x\n", code, (u_int32_t)dest);
1.1       cgd      1112: #endif
                   1113:                }
                   1114:        }
                   1115:
1.27      thorpej  1116:        error = ip_output(m, (struct mbuf *)0, &ipforward_rt,
                   1117:            (IP_FORWARDING | (ip_directedbcast ? IP_ALLOWBROADCAST : 0)), 0);
1.1       cgd      1118:        if (error)
                   1119:                ipstat.ips_cantforward++;
                   1120:        else {
                   1121:                ipstat.ips_forward++;
                   1122:                if (type)
                   1123:                        ipstat.ips_redirectsent++;
                   1124:                else {
                   1125:                        if (mcopy)
                   1126:                                m_freem(mcopy);
                   1127:                        return;
                   1128:                }
                   1129:        }
                   1130:        if (mcopy == NULL)
                   1131:                return;
1.13      mycroft  1132:        destifp = NULL;
                   1133:
1.1       cgd      1134:        switch (error) {
                   1135:
                   1136:        case 0:                         /* forwarded, but need redirect */
                   1137:                /* type, code set above */
                   1138:                break;
                   1139:
                   1140:        case ENETUNREACH:               /* shouldn't happen, checked above */
                   1141:        case EHOSTUNREACH:
                   1142:        case ENETDOWN:
                   1143:        case EHOSTDOWN:
                   1144:        default:
                   1145:                type = ICMP_UNREACH;
                   1146:                code = ICMP_UNREACH_HOST;
                   1147:                break;
                   1148:
                   1149:        case EMSGSIZE:
                   1150:                type = ICMP_UNREACH;
                   1151:                code = ICMP_UNREACH_NEEDFRAG;
1.13      mycroft  1152:                if (ipforward_rt.ro_rt)
                   1153:                        destifp = ipforward_rt.ro_rt->rt_ifp;
1.1       cgd      1154:                ipstat.ips_cantfrag++;
                   1155:                break;
                   1156:
                   1157:        case ENOBUFS:
                   1158:                type = ICMP_SOURCEQUENCH;
                   1159:                code = 0;
                   1160:                break;
                   1161:        }
1.13      mycroft  1162:        icmp_error(mcopy, type, code, dest, destifp);
1.44      thorpej  1163: }
                   1164:
                   1165: void
                   1166: ip_savecontrol(inp, mp, ip, m)
                   1167:        register struct inpcb *inp;
                   1168:        register struct mbuf **mp;
                   1169:        register struct ip *ip;
                   1170:        register struct mbuf *m;
                   1171: {
                   1172:
                   1173:        if (inp->inp_socket->so_options & SO_TIMESTAMP) {
                   1174:                struct timeval tv;
                   1175:
                   1176:                microtime(&tv);
                   1177:                *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
                   1178:                    SCM_TIMESTAMP, SOL_SOCKET);
                   1179:                if (*mp)
                   1180:                        mp = &(*mp)->m_next;
                   1181:        }
                   1182:        if (inp->inp_flags & INP_RECVDSTADDR) {
                   1183:                *mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
                   1184:                    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
                   1185:                if (*mp)
                   1186:                        mp = &(*mp)->m_next;
                   1187:        }
                   1188: #ifdef notyet
                   1189:        /*
                   1190:         * XXX
                   1191:         * Moving these out of udp_input() made them even more broken
                   1192:         * than they already were.
                   1193:         *      - fenner@parc.xerox.com
                   1194:         */
                   1195:        /* options were tossed already */
                   1196:        if (inp->inp_flags & INP_RECVOPTS) {
                   1197:                *mp = sbcreatecontrol((caddr_t) opts_deleted_above,
                   1198:                    sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
                   1199:                if (*mp)
                   1200:                        mp = &(*mp)->m_next;
                   1201:        }
                   1202:        /* ip_srcroute doesn't do what we want here, need to fix */
                   1203:        if (inp->inp_flags & INP_RECVRETOPTS) {
                   1204:                *mp = sbcreatecontrol((caddr_t) ip_srcroute(),
                   1205:                    sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
                   1206:                if (*mp)
                   1207:                        mp = &(*mp)->m_next;
                   1208:        }
                   1209: #endif
                   1210:        if (inp->inp_flags & INP_RECVIF) {
                   1211:                struct sockaddr_dl sdl;
                   1212:
                   1213:                sdl.sdl_len = offsetof(struct sockaddr_dl, sdl_data[0]);
                   1214:                sdl.sdl_family = AF_LINK;
                   1215:                sdl.sdl_index = m->m_pkthdr.rcvif ?
                   1216:                    m->m_pkthdr.rcvif->if_index : 0;
                   1217:                sdl.sdl_nlen = sdl.sdl_alen = sdl.sdl_slen = 0;
                   1218:                *mp = sbcreatecontrol((caddr_t) &sdl, sdl.sdl_len,
                   1219:                    IP_RECVIF, IPPROTO_IP);
                   1220:                if (*mp)
                   1221:                        mp = &(*mp)->m_next;
                   1222:        }
1.13      mycroft  1223: }
                   1224:
                   1225: int
                   1226: ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
                   1227:        int *name;
                   1228:        u_int namelen;
                   1229:        void *oldp;
                   1230:        size_t *oldlenp;
                   1231:        void *newp;
                   1232:        size_t newlen;
                   1233: {
                   1234:        /* All sysctl names at this level are terminal. */
                   1235:        if (namelen != 1)
                   1236:                return (ENOTDIR);
                   1237:
                   1238:        switch (name[0]) {
                   1239:        case IPCTL_FORWARDING:
                   1240:                return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding));
                   1241:        case IPCTL_SENDREDIRECTS:
                   1242:                return (sysctl_int(oldp, oldlenp, newp, newlen,
                   1243:                        &ipsendredirects));
                   1244:        case IPCTL_DEFTTL:
                   1245:                return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl));
                   1246: #ifdef notyet
                   1247:        case IPCTL_DEFMTU:
                   1248:                return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu));
                   1249: #endif
1.26      thorpej  1250:        case IPCTL_FORWSRCRT:
                   1251:                /*
                   1252:                 * Don't allow this to change in a secure environment.
                   1253:                 */
                   1254:                if (securelevel > 0)
                   1255:                        return (EPERM);
                   1256:                return (sysctl_int(oldp, oldlenp, newp, newlen,
                   1257:                    &ip_forwsrcrt));
1.27      thorpej  1258:        case IPCTL_DIRECTEDBCAST:
                   1259:                return (sysctl_int(oldp, oldlenp, newp, newlen,
                   1260:                    &ip_directedbcast));
1.13      mycroft  1261:        default:
                   1262:                return (EOPNOTSUPP);
                   1263:        }
                   1264:        /* NOTREACHED */
1.1       cgd      1265: }

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