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Annotation of src/sys/netinet/ip_input.c, Revision 1.44

1.44    ! thorpej     1: /*     $NetBSD: ip_input.c,v 1.43 1996/12/20 09:08:14 mrg 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>
1.1       cgd        57:
1.5       mycroft    58: #include <netinet/in.h>
                     59: #include <netinet/in_systm.h>
                     60: #include <netinet/ip.h>
                     61: #include <netinet/in_pcb.h>
                     62: #include <netinet/in_var.h>
                     63: #include <netinet/ip_var.h>
                     64: #include <netinet/ip_icmp.h>
1.1       cgd        65:
1.36      mrg        66: #ifdef PFIL_HOOKS
                     67: #include <net/pfil.h>
                     68: #endif /* PFIL_HOOKS */
                     69:
1.44    ! thorpej    70: /* XXX should really put this in libkern.h */
        !            71: #define        offsetof(type, member)  ((size_t)(&((type *)0)->member))
        !            72:
1.1       cgd        73: #ifndef        IPFORWARDING
                     74: #ifdef GATEWAY
                     75: #define        IPFORWARDING    1       /* forward IP packets not for us */
                     76: #else /* GATEWAY */
                     77: #define        IPFORWARDING    0       /* don't forward IP packets not for us */
                     78: #endif /* GATEWAY */
                     79: #endif /* IPFORWARDING */
                     80: #ifndef        IPSENDREDIRECTS
                     81: #define        IPSENDREDIRECTS 1
                     82: #endif
1.26      thorpej    83: #ifndef IPFORWSRCRT
                     84: #define        IPFORWSRCRT     1       /* allow source-routed packets */
                     85: #endif
1.27      thorpej    86: /*
                     87:  * Note: DIRECTED_BROADCAST is handled this way so that previous
                     88:  * configuration using this option will Just Work.
                     89:  */
                     90: #ifndef IPDIRECTEDBCAST
                     91: #ifdef DIRECTED_BROADCAST
                     92: #define IPDIRECTEDBCAST        1
                     93: #else
                     94: #define        IPDIRECTEDBCAST 0
                     95: #endif /* DIRECTED_BROADCAST */
                     96: #endif /* IPDIRECTEDBCAST */
1.1       cgd        97: int    ipforwarding = IPFORWARDING;
                     98: int    ipsendredirects = IPSENDREDIRECTS;
1.13      mycroft    99: int    ip_defttl = IPDEFTTL;
1.26      thorpej   100: int    ip_forwsrcrt = IPFORWSRCRT;
1.27      thorpej   101: int    ip_directedbcast = IPDIRECTEDBCAST;
1.1       cgd       102: #ifdef DIAGNOSTIC
                    103: int    ipprintfs = 0;
                    104: #endif
                    105:
                    106: extern struct domain inetdomain;
                    107: extern struct protosw inetsw[];
                    108: u_char ip_protox[IPPROTO_MAX];
                    109: int    ipqmaxlen = IFQ_MAXLEN;
1.22      mycroft   110: struct in_ifaddrhead in_ifaddr;
1.13      mycroft   111: struct ifqueue ipintrq;
1.1       cgd       112:
                    113: /*
                    114:  * We need to save the IP options in case a protocol wants to respond
                    115:  * to an incoming packet over the same route if the packet got here
                    116:  * using IP source routing.  This allows connection establishment and
                    117:  * maintenance when the remote end is on a network that is not known
                    118:  * to us.
                    119:  */
                    120: int    ip_nhops = 0;
                    121: static struct ip_srcrt {
                    122:        struct  in_addr dst;                    /* final destination */
                    123:        char    nop;                            /* one NOP to align */
                    124:        char    srcopt[IPOPT_OFFSET + 1];       /* OPTVAL, OLEN and OFFSET */
                    125:        struct  in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
                    126: } ip_srcrt;
                    127:
1.13      mycroft   128: static void save_rte __P((u_char *, struct in_addr));
1.35      mycroft   129:
1.1       cgd       130: /*
                    131:  * IP initialization: fill in IP protocol switch table.
                    132:  * All protocols not implemented in kernel go to raw IP protocol handler.
                    133:  */
1.8       mycroft   134: void
1.1       cgd       135: ip_init()
                    136: {
                    137:        register struct protosw *pr;
                    138:        register int i;
                    139:
                    140:        pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
                    141:        if (pr == 0)
                    142:                panic("ip_init");
                    143:        for (i = 0; i < IPPROTO_MAX; i++)
                    144:                ip_protox[i] = pr - inetsw;
                    145:        for (pr = inetdomain.dom_protosw;
                    146:            pr < inetdomain.dom_protoswNPROTOSW; pr++)
                    147:                if (pr->pr_domain->dom_family == PF_INET &&
                    148:                    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
                    149:                        ip_protox[pr->pr_protocol] = pr - inetsw;
1.25      cgd       150:        LIST_INIT(&ipq);
1.1       cgd       151:        ip_id = time.tv_sec & 0xffff;
                    152:        ipintrq.ifq_maxlen = ipqmaxlen;
1.22      mycroft   153:        TAILQ_INIT(&in_ifaddr);
1.1       cgd       154: }
                    155:
                    156: struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
                    157: struct route ipforward_rt;
                    158:
                    159: /*
                    160:  * Ip input routine.  Checksum and byte swap header.  If fragmented
                    161:  * try to reassemble.  Process options.  Pass to next level.
                    162:  */
1.8       mycroft   163: void
1.1       cgd       164: ipintr()
                    165: {
1.33      mrg       166:        register struct ip *ip = NULL;
1.1       cgd       167:        register struct mbuf *m;
                    168:        register struct ipq *fp;
                    169:        register struct in_ifaddr *ia;
1.25      cgd       170:        struct ipqent *ipqe;
1.35      mycroft   171:        int hlen = 0, mff, len, s;
1.36      mrg       172: #ifdef PFIL_HOOKS
1.33      mrg       173:        struct packet_filter_hook *pfh;
                    174:        struct mbuf *m0;
1.43      mrg       175:        int rv;
1.36      mrg       176: #endif /* PFIL_HOOKS */
1.1       cgd       177:
                    178: next:
                    179:        /*
                    180:         * Get next datagram off input queue and get IP header
                    181:         * in first mbuf.
                    182:         */
                    183:        s = splimp();
                    184:        IF_DEQUEUE(&ipintrq, m);
                    185:        splx(s);
1.13      mycroft   186:        if (m == 0)
1.1       cgd       187:                return;
                    188: #ifdef DIAGNOSTIC
                    189:        if ((m->m_flags & M_PKTHDR) == 0)
                    190:                panic("ipintr no HDR");
                    191: #endif
                    192:        /*
                    193:         * If no IP addresses have been set yet but the interfaces
                    194:         * are receiving, can't do anything with incoming packets yet.
                    195:         */
1.22      mycroft   196:        if (in_ifaddr.tqh_first == 0)
1.1       cgd       197:                goto bad;
                    198:        ipstat.ips_total++;
                    199:        if (m->m_len < sizeof (struct ip) &&
                    200:            (m = m_pullup(m, sizeof (struct ip))) == 0) {
                    201:                ipstat.ips_toosmall++;
                    202:                goto next;
                    203:        }
                    204:        ip = mtod(m, struct ip *);
1.13      mycroft   205:        if (ip->ip_v != IPVERSION) {
                    206:                ipstat.ips_badvers++;
                    207:                goto bad;
                    208:        }
1.1       cgd       209:        hlen = ip->ip_hl << 2;
                    210:        if (hlen < sizeof(struct ip)) { /* minimum header length */
                    211:                ipstat.ips_badhlen++;
                    212:                goto bad;
                    213:        }
                    214:        if (hlen > m->m_len) {
                    215:                if ((m = m_pullup(m, hlen)) == 0) {
                    216:                        ipstat.ips_badhlen++;
                    217:                        goto next;
                    218:                }
                    219:                ip = mtod(m, struct ip *);
                    220:        }
1.28      christos  221:        if ((ip->ip_sum = in_cksum(m, hlen)) != 0) {
1.1       cgd       222:                ipstat.ips_badsum++;
                    223:                goto bad;
                    224:        }
                    225:
                    226:        /*
                    227:         * Convert fields to host representation.
                    228:         */
                    229:        NTOHS(ip->ip_len);
                    230:        NTOHS(ip->ip_id);
                    231:        NTOHS(ip->ip_off);
1.35      mycroft   232:        len = ip->ip_len;
1.1       cgd       233:
                    234:        /*
                    235:         * Check that the amount of data in the buffers
                    236:         * is as at least much as the IP header would have us expect.
                    237:         * Trim mbufs if longer than we expect.
                    238:         * Drop packet if shorter than we expect.
                    239:         */
1.35      mycroft   240:        if (m->m_pkthdr.len < len) {
1.1       cgd       241:                ipstat.ips_tooshort++;
                    242:                goto bad;
                    243:        }
1.35      mycroft   244:        if (m->m_pkthdr.len > len) {
1.1       cgd       245:                if (m->m_len == m->m_pkthdr.len) {
1.35      mycroft   246:                        m->m_len = len;
                    247:                        m->m_pkthdr.len = len;
1.1       cgd       248:                } else
1.35      mycroft   249:                        m_adj(m, len - m->m_pkthdr.len);
1.1       cgd       250:        }
                    251:
1.36      mrg       252: #ifdef PFIL_HOOKS
1.33      mrg       253:        /*
                    254:         * Run through list of hooks for input packets.
                    255:         */
                    256:        m0 = m;
                    257:        for (pfh = pfil_hook_get(PFIL_IN); pfh; pfh = pfh->pfil_link.le_next)
                    258:                if (pfh->pfil_func) {
1.43      mrg       259:                        rv = pfh->pfil_func(ip, hlen, m->m_pkthdr.rcvif, 0, &m0);
                    260:                        ip = mtod(m = m0, struct ip *);
                    261:                        if (rv)
1.40      veego     262:                                goto next;
1.33      mrg       263:                }
1.36      mrg       264: #endif /* PFIL_HOOKS */
1.33      mrg       265:
1.1       cgd       266:        /*
                    267:         * Process options and, if not destined for us,
                    268:         * ship it on.  ip_dooptions returns 1 when an
                    269:         * error was detected (causing an icmp message
                    270:         * to be sent and the original packet to be freed).
                    271:         */
                    272:        ip_nhops = 0;           /* for source routed packets */
                    273:        if (hlen > sizeof (struct ip) && ip_dooptions(m))
                    274:                goto next;
                    275:
                    276:        /*
                    277:         * Check our list of addresses, to see if the packet is for us.
                    278:         */
1.22      mycroft   279:        for (ia = in_ifaddr.tqh_first; ia; ia = ia->ia_list.tqe_next) {
1.35      mycroft   280:                if (in_hosteq(ip->ip_dst, ia->ia_addr.sin_addr))
1.1       cgd       281:                        goto ours;
1.27      thorpej   282:                if (((ip_directedbcast == 0) || (ip_directedbcast &&
                    283:                    ia->ia_ifp == m->m_pkthdr.rcvif)) &&
1.1       cgd       284:                    (ia->ia_ifp->if_flags & IFF_BROADCAST)) {
1.35      mycroft   285:                        if (in_hosteq(ip->ip_dst, ia->ia_broadaddr.sin_addr) ||
                    286:                            in_hosteq(ip->ip_dst, ia->ia_netbroadcast) ||
1.20      mycroft   287:                            /*
                    288:                             * Look for all-0's host part (old broadcast addr),
                    289:                             * either for subnet or net.
                    290:                             */
                    291:                            ip->ip_dst.s_addr == ia->ia_subnet ||
1.18      mycroft   292:                            ip->ip_dst.s_addr == ia->ia_net)
1.1       cgd       293:                                goto ours;
                    294:                }
                    295:        }
1.18      mycroft   296:        if (IN_MULTICAST(ip->ip_dst.s_addr)) {
1.4       hpeyerl   297:                struct in_multi *inm;
                    298: #ifdef MROUTING
                    299:                extern struct socket *ip_mrouter;
1.10      brezak    300:
                    301:                if (m->m_flags & M_EXT) {
                    302:                        if ((m = m_pullup(m, hlen)) == 0) {
                    303:                                ipstat.ips_toosmall++;
                    304:                                goto next;
                    305:                        }
                    306:                        ip = mtod(m, struct ip *);
                    307:                }
1.4       hpeyerl   308:
                    309:                if (ip_mrouter) {
                    310:                        /*
                    311:                         * If we are acting as a multicast router, all
                    312:                         * incoming multicast packets are passed to the
                    313:                         * kernel-level multicast forwarding function.
                    314:                         * The packet is returned (relatively) intact; if
                    315:                         * ip_mforward() returns a non-zero value, the packet
                    316:                         * must be discarded, else it may be accepted below.
                    317:                         *
                    318:                         * (The IP ident field is put in the same byte order
                    319:                         * as expected when ip_mforward() is called from
                    320:                         * ip_output().)
                    321:                         */
                    322:                        ip->ip_id = htons(ip->ip_id);
1.13      mycroft   323:                        if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) {
                    324:                                ipstat.ips_cantforward++;
1.4       hpeyerl   325:                                m_freem(m);
                    326:                                goto next;
                    327:                        }
                    328:                        ip->ip_id = ntohs(ip->ip_id);
                    329:
                    330:                        /*
                    331:                         * The process-level routing demon needs to receive
                    332:                         * all multicast IGMP packets, whether or not this
                    333:                         * host belongs to their destination groups.
                    334:                         */
                    335:                        if (ip->ip_p == IPPROTO_IGMP)
                    336:                                goto ours;
1.13      mycroft   337:                        ipstat.ips_forward++;
1.4       hpeyerl   338:                }
                    339: #endif
                    340:                /*
                    341:                 * See if we belong to the destination multicast group on the
                    342:                 * arrival interface.
                    343:                 */
                    344:                IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
                    345:                if (inm == NULL) {
1.13      mycroft   346:                        ipstat.ips_cantforward++;
1.4       hpeyerl   347:                        m_freem(m);
                    348:                        goto next;
                    349:                }
                    350:                goto ours;
                    351:        }
1.19      mycroft   352:        if (ip->ip_dst.s_addr == INADDR_BROADCAST ||
1.35      mycroft   353:            in_nullhost(ip->ip_dst))
1.1       cgd       354:                goto ours;
                    355:
                    356:        /*
                    357:         * Not for us; forward if possible and desirable.
                    358:         */
                    359:        if (ipforwarding == 0) {
                    360:                ipstat.ips_cantforward++;
                    361:                m_freem(m);
                    362:        } else
                    363:                ip_forward(m, 0);
                    364:        goto next;
                    365:
                    366: ours:
                    367:        /*
                    368:         * If offset or IP_MF are set, must reassemble.
                    369:         * Otherwise, nothing need be done.
                    370:         * (We could look in the reassembly queue to see
                    371:         * if the packet was previously fragmented,
                    372:         * but it's not worth the time; just let them time out.)
                    373:         */
1.37      perry     374:        if (ip->ip_off & ~(IP_DF|IP_RF)) {
1.1       cgd       375:                if (m->m_flags & M_EXT) {               /* XXX */
                    376:                        if ((m = m_pullup(m, sizeof (struct ip))) == 0) {
                    377:                                ipstat.ips_toosmall++;
                    378:                                goto next;
                    379:                        }
                    380:                        ip = mtod(m, struct ip *);
                    381:                }
                    382:                /*
                    383:                 * Look for queue of fragments
                    384:                 * of this datagram.
                    385:                 */
1.25      cgd       386:                for (fp = ipq.lh_first; fp != NULL; fp = fp->ipq_q.le_next)
1.1       cgd       387:                        if (ip->ip_id == fp->ipq_id &&
1.35      mycroft   388:                            in_hosteq(ip->ip_src, fp->ipq_src) &&
                    389:                            in_hosteq(ip->ip_dst, fp->ipq_dst) &&
1.1       cgd       390:                            ip->ip_p == fp->ipq_p)
                    391:                                goto found;
                    392:                fp = 0;
                    393: found:
                    394:
                    395:                /*
                    396:                 * Adjust ip_len to not reflect header,
1.25      cgd       397:                 * set ipqe_mff if more fragments are expected,
1.1       cgd       398:                 * convert offset of this to bytes.
                    399:                 */
                    400:                ip->ip_len -= hlen;
1.25      cgd       401:                mff = (ip->ip_off & IP_MF) != 0;
                    402:                if (mff) {
1.16      cgd       403:                        /*
                    404:                         * Make sure that fragments have a data length
                    405:                         * that's a non-zero multiple of 8 bytes.
                    406:                         */
1.17      cgd       407:                        if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
1.16      cgd       408:                                ipstat.ips_badfrags++;
                    409:                                goto bad;
                    410:                        }
                    411:                }
1.1       cgd       412:                ip->ip_off <<= 3;
                    413:
                    414:                /*
                    415:                 * If datagram marked as having more fragments
                    416:                 * or if this is not the first fragment,
                    417:                 * attempt reassembly; if it succeeds, proceed.
                    418:                 */
1.25      cgd       419:                if (mff || ip->ip_off) {
1.1       cgd       420:                        ipstat.ips_fragments++;
1.25      cgd       421:                        MALLOC(ipqe, struct ipqent *, sizeof (struct ipqent),
                    422:                            M_IPQ, M_NOWAIT);
                    423:                        if (ipqe == NULL) {
                    424:                                ipstat.ips_rcvmemdrop++;
                    425:                                goto bad;
                    426:                        }
                    427:                        ipqe->ipqe_mff = mff;
                    428:                        ipqe->ipqe_ip = ip;
                    429:                        ip = ip_reass(ipqe, fp);
1.1       cgd       430:                        if (ip == 0)
                    431:                                goto next;
1.13      mycroft   432:                        ipstat.ips_reassembled++;
1.1       cgd       433:                        m = dtom(ip);
                    434:                } else
                    435:                        if (fp)
                    436:                                ip_freef(fp);
                    437:        } else
                    438:                ip->ip_len -= hlen;
                    439:
                    440:        /*
                    441:         * Switch out to protocol's input routine.
                    442:         */
                    443:        ipstat.ips_delivered++;
                    444:        (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
                    445:        goto next;
                    446: bad:
                    447:        m_freem(m);
                    448:        goto next;
                    449: }
                    450:
                    451: /*
                    452:  * Take incoming datagram fragment and try to
                    453:  * reassemble it into whole datagram.  If a chain for
                    454:  * reassembly of this datagram already exists, then it
                    455:  * is given as fp; otherwise have to make a chain.
                    456:  */
                    457: struct ip *
1.25      cgd       458: ip_reass(ipqe, fp)
                    459:        register struct ipqent *ipqe;
1.1       cgd       460:        register struct ipq *fp;
                    461: {
1.25      cgd       462:        register struct mbuf *m = dtom(ipqe->ipqe_ip);
                    463:        register struct ipqent *nq, *p, *q;
                    464:        struct ip *ip;
1.1       cgd       465:        struct mbuf *t;
1.25      cgd       466:        int hlen = ipqe->ipqe_ip->ip_hl << 2;
1.1       cgd       467:        int i, next;
                    468:
                    469:        /*
                    470:         * Presence of header sizes in mbufs
                    471:         * would confuse code below.
                    472:         */
                    473:        m->m_data += hlen;
                    474:        m->m_len -= hlen;
                    475:
                    476:        /*
                    477:         * If first fragment to arrive, create a reassembly queue.
                    478:         */
                    479:        if (fp == 0) {
                    480:                if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
                    481:                        goto dropfrag;
                    482:                fp = mtod(t, struct ipq *);
1.25      cgd       483:                LIST_INSERT_HEAD(&ipq, fp, ipq_q);
1.1       cgd       484:                fp->ipq_ttl = IPFRAGTTL;
1.25      cgd       485:                fp->ipq_p = ipqe->ipqe_ip->ip_p;
                    486:                fp->ipq_id = ipqe->ipqe_ip->ip_id;
                    487:                LIST_INIT(&fp->ipq_fragq);
                    488:                fp->ipq_src = ipqe->ipqe_ip->ip_src;
                    489:                fp->ipq_dst = ipqe->ipqe_ip->ip_dst;
                    490:                p = NULL;
1.1       cgd       491:                goto insert;
                    492:        }
                    493:
                    494:        /*
                    495:         * Find a segment which begins after this one does.
                    496:         */
1.25      cgd       497:        for (p = NULL, q = fp->ipq_fragq.lh_first; q != NULL;
                    498:            p = q, q = q->ipqe_q.le_next)
                    499:                if (q->ipqe_ip->ip_off > ipqe->ipqe_ip->ip_off)
1.1       cgd       500:                        break;
                    501:
                    502:        /*
                    503:         * If there is a preceding segment, it may provide some of
                    504:         * our data already.  If so, drop the data from the incoming
                    505:         * segment.  If it provides all of our data, drop us.
                    506:         */
1.25      cgd       507:        if (p != NULL) {
                    508:                i = p->ipqe_ip->ip_off + p->ipqe_ip->ip_len -
                    509:                    ipqe->ipqe_ip->ip_off;
1.1       cgd       510:                if (i > 0) {
1.25      cgd       511:                        if (i >= ipqe->ipqe_ip->ip_len)
1.1       cgd       512:                                goto dropfrag;
1.25      cgd       513:                        m_adj(dtom(ipqe->ipqe_ip), i);
                    514:                        ipqe->ipqe_ip->ip_off += i;
                    515:                        ipqe->ipqe_ip->ip_len -= i;
1.1       cgd       516:                }
                    517:        }
                    518:
                    519:        /*
                    520:         * While we overlap succeeding segments trim them or,
                    521:         * if they are completely covered, dequeue them.
                    522:         */
1.25      cgd       523:        for (; q != NULL && ipqe->ipqe_ip->ip_off + ipqe->ipqe_ip->ip_len >
                    524:            q->ipqe_ip->ip_off; q = nq) {
                    525:                i = (ipqe->ipqe_ip->ip_off + ipqe->ipqe_ip->ip_len) -
                    526:                    q->ipqe_ip->ip_off;
                    527:                if (i < q->ipqe_ip->ip_len) {
                    528:                        q->ipqe_ip->ip_len -= i;
                    529:                        q->ipqe_ip->ip_off += i;
                    530:                        m_adj(dtom(q->ipqe_ip), i);
1.1       cgd       531:                        break;
                    532:                }
1.25      cgd       533:                nq = q->ipqe_q.le_next;
                    534:                m_freem(dtom(q->ipqe_ip));
                    535:                LIST_REMOVE(q, ipqe_q);
                    536:                FREE(q, M_IPQ);
1.1       cgd       537:        }
                    538:
                    539: insert:
                    540:        /*
                    541:         * Stick new segment in its place;
                    542:         * check for complete reassembly.
                    543:         */
1.25      cgd       544:        if (p == NULL) {
                    545:                LIST_INSERT_HEAD(&fp->ipq_fragq, ipqe, ipqe_q);
                    546:        } else {
                    547:                LIST_INSERT_AFTER(p, ipqe, ipqe_q);
                    548:        }
1.1       cgd       549:        next = 0;
1.25      cgd       550:        for (p = NULL, q = fp->ipq_fragq.lh_first; q != NULL;
                    551:            p = q, q = q->ipqe_q.le_next) {
                    552:                if (q->ipqe_ip->ip_off != next)
1.1       cgd       553:                        return (0);
1.25      cgd       554:                next += q->ipqe_ip->ip_len;
1.1       cgd       555:        }
1.25      cgd       556:        if (p->ipqe_mff)
1.1       cgd       557:                return (0);
                    558:
                    559:        /*
1.41      thorpej   560:         * Reassembly is complete.  Check for a bogus message size and
                    561:         * concatenate fragments.
1.1       cgd       562:         */
1.25      cgd       563:        q = fp->ipq_fragq.lh_first;
                    564:        ip = q->ipqe_ip;
1.41      thorpej   565:        if ((next + (ip->ip_hl << 2)) > IP_MAXPACKET) {
                    566:                ipstat.ips_toolong++;
                    567:                ip_freef(fp);
                    568:                return (0);
                    569:        }
1.25      cgd       570:        m = dtom(q->ipqe_ip);
1.1       cgd       571:        t = m->m_next;
                    572:        m->m_next = 0;
                    573:        m_cat(m, t);
1.25      cgd       574:        nq = q->ipqe_q.le_next;
                    575:        FREE(q, M_IPQ);
                    576:        for (q = nq; q != NULL; q = nq) {
                    577:                t = dtom(q->ipqe_ip);
                    578:                nq = q->ipqe_q.le_next;
                    579:                FREE(q, M_IPQ);
1.1       cgd       580:                m_cat(m, t);
                    581:        }
                    582:
                    583:        /*
                    584:         * Create header for new ip packet by
                    585:         * modifying header of first packet;
                    586:         * dequeue and discard fragment reassembly header.
                    587:         * Make header visible.
                    588:         */
                    589:        ip->ip_len = next;
1.25      cgd       590:        ip->ip_src = fp->ipq_src;
                    591:        ip->ip_dst = fp->ipq_dst;
                    592:        LIST_REMOVE(fp, ipq_q);
1.1       cgd       593:        (void) m_free(dtom(fp));
                    594:        m->m_len += (ip->ip_hl << 2);
                    595:        m->m_data -= (ip->ip_hl << 2);
                    596:        /* some debugging cruft by sklower, below, will go away soon */
                    597:        if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
                    598:                register int plen = 0;
                    599:                for (t = m; m; m = m->m_next)
                    600:                        plen += m->m_len;
                    601:                t->m_pkthdr.len = plen;
                    602:        }
1.25      cgd       603:        return (ip);
1.1       cgd       604:
                    605: dropfrag:
                    606:        ipstat.ips_fragdropped++;
                    607:        m_freem(m);
1.25      cgd       608:        FREE(ipqe, M_IPQ);
1.1       cgd       609:        return (0);
                    610: }
                    611:
                    612: /*
                    613:  * Free a fragment reassembly header and all
                    614:  * associated datagrams.
                    615:  */
1.8       mycroft   616: void
1.1       cgd       617: ip_freef(fp)
                    618:        struct ipq *fp;
                    619: {
1.25      cgd       620:        register struct ipqent *q, *p;
1.1       cgd       621:
1.25      cgd       622:        for (q = fp->ipq_fragq.lh_first; q != NULL; q = p) {
                    623:                p = q->ipqe_q.le_next;
                    624:                m_freem(dtom(q->ipqe_ip));
                    625:                LIST_REMOVE(q, ipqe_q);
                    626:                FREE(q, M_IPQ);
1.1       cgd       627:        }
1.25      cgd       628:        LIST_REMOVE(fp, ipq_q);
1.1       cgd       629:        (void) m_free(dtom(fp));
                    630: }
                    631:
                    632: /*
                    633:  * IP timer processing;
                    634:  * if a timer expires on a reassembly
                    635:  * queue, discard it.
                    636:  */
1.8       mycroft   637: void
1.1       cgd       638: ip_slowtimo()
                    639: {
1.25      cgd       640:        register struct ipq *fp, *nfp;
1.24      mycroft   641:        int s = splsoftnet();
1.1       cgd       642:
1.25      cgd       643:        for (fp = ipq.lh_first; fp != NULL; fp = nfp) {
                    644:                nfp = fp->ipq_q.le_next;
                    645:                if (--fp->ipq_ttl == 0) {
1.1       cgd       646:                        ipstat.ips_fragtimeout++;
1.25      cgd       647:                        ip_freef(fp);
1.1       cgd       648:                }
                    649:        }
                    650:        splx(s);
                    651: }
                    652:
                    653: /*
                    654:  * Drain off all datagram fragments.
                    655:  */
1.8       mycroft   656: void
1.1       cgd       657: ip_drain()
                    658: {
                    659:
1.25      cgd       660:        while (ipq.lh_first != NULL) {
1.1       cgd       661:                ipstat.ips_fragdropped++;
1.25      cgd       662:                ip_freef(ipq.lh_first);
1.1       cgd       663:        }
                    664: }
                    665:
                    666: /*
                    667:  * Do option processing on a datagram,
                    668:  * possibly discarding it if bad options are encountered,
                    669:  * or forwarding it if source-routed.
                    670:  * Returns 1 if packet has been forwarded/freed,
                    671:  * 0 if the packet should be processed further.
                    672:  */
1.8       mycroft   673: int
1.1       cgd       674: ip_dooptions(m)
                    675:        struct mbuf *m;
                    676: {
                    677:        register struct ip *ip = mtod(m, struct ip *);
                    678:        register u_char *cp;
                    679:        register struct ip_timestamp *ipt;
                    680:        register struct in_ifaddr *ia;
                    681:        int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
1.13      mycroft   682:        struct in_addr *sin, dst;
1.1       cgd       683:        n_time ntime;
                    684:
1.13      mycroft   685:        dst = ip->ip_dst;
1.1       cgd       686:        cp = (u_char *)(ip + 1);
                    687:        cnt = (ip->ip_hl << 2) - sizeof (struct ip);
                    688:        for (; cnt > 0; cnt -= optlen, cp += optlen) {
                    689:                opt = cp[IPOPT_OPTVAL];
                    690:                if (opt == IPOPT_EOL)
                    691:                        break;
                    692:                if (opt == IPOPT_NOP)
                    693:                        optlen = 1;
                    694:                else {
                    695:                        optlen = cp[IPOPT_OLEN];
                    696:                        if (optlen <= 0 || optlen > cnt) {
                    697:                                code = &cp[IPOPT_OLEN] - (u_char *)ip;
                    698:                                goto bad;
                    699:                        }
                    700:                }
                    701:                switch (opt) {
                    702:
                    703:                default:
                    704:                        break;
                    705:
                    706:                /*
                    707:                 * Source routing with record.
                    708:                 * Find interface with current destination address.
                    709:                 * If none on this machine then drop if strictly routed,
                    710:                 * or do nothing if loosely routed.
                    711:                 * Record interface address and bring up next address
                    712:                 * component.  If strictly routed make sure next
                    713:                 * address is on directly accessible net.
                    714:                 */
                    715:                case IPOPT_LSRR:
                    716:                case IPOPT_SSRR:
                    717:                        if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
                    718:                                code = &cp[IPOPT_OFFSET] - (u_char *)ip;
                    719:                                goto bad;
                    720:                        }
                    721:                        ipaddr.sin_addr = ip->ip_dst;
1.19      mycroft   722:                        ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)));
1.1       cgd       723:                        if (ia == 0) {
                    724:                                if (opt == IPOPT_SSRR) {
                    725:                                        type = ICMP_UNREACH;
                    726:                                        code = ICMP_UNREACH_SRCFAIL;
                    727:                                        goto bad;
                    728:                                }
                    729:                                /*
                    730:                                 * Loose routing, and not at next destination
                    731:                                 * yet; nothing to do except forward.
                    732:                                 */
                    733:                                break;
                    734:                        }
                    735:                        off--;                  /* 0 origin */
                    736:                        if (off > optlen - sizeof(struct in_addr)) {
                    737:                                /*
                    738:                                 * End of source route.  Should be for us.
                    739:                                 */
                    740:                                save_rte(cp, ip->ip_src);
                    741:                                break;
                    742:                        }
                    743:                        /*
                    744:                         * locate outgoing interface
                    745:                         */
                    746:                        bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
                    747:                            sizeof(ipaddr.sin_addr));
                    748:                        if (opt == IPOPT_SSRR) {
                    749: #define        INA     struct in_ifaddr *
                    750: #define        SA      struct sockaddr *
1.29      mrg       751:                            ia = (INA)ifa_ifwithladdr((SA)&ipaddr);
1.1       cgd       752:                        } else
                    753:                                ia = ip_rtaddr(ipaddr.sin_addr);
                    754:                        if (ia == 0) {
                    755:                                type = ICMP_UNREACH;
                    756:                                code = ICMP_UNREACH_SRCFAIL;
                    757:                                goto bad;
                    758:                        }
                    759:                        ip->ip_dst = ipaddr.sin_addr;
1.20      mycroft   760:                        bcopy((caddr_t)&ia->ia_addr.sin_addr,
1.1       cgd       761:                            (caddr_t)(cp + off), sizeof(struct in_addr));
                    762:                        cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1.13      mycroft   763:                        /*
                    764:                         * Let ip_intr's mcast routing check handle mcast pkts
                    765:                         */
1.18      mycroft   766:                        forward = !IN_MULTICAST(ip->ip_dst.s_addr);
1.1       cgd       767:                        break;
                    768:
                    769:                case IPOPT_RR:
                    770:                        if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
                    771:                                code = &cp[IPOPT_OFFSET] - (u_char *)ip;
                    772:                                goto bad;
                    773:                        }
                    774:                        /*
                    775:                         * If no space remains, ignore.
                    776:                         */
                    777:                        off--;                  /* 0 origin */
                    778:                        if (off > optlen - sizeof(struct in_addr))
                    779:                                break;
                    780:                        bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
                    781:                            sizeof(ipaddr.sin_addr));
                    782:                        /*
                    783:                         * locate outgoing interface; if we're the destination,
                    784:                         * use the incoming interface (should be same).
                    785:                         */
                    786:                        if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
                    787:                            (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
                    788:                                type = ICMP_UNREACH;
                    789:                                code = ICMP_UNREACH_HOST;
                    790:                                goto bad;
                    791:                        }
1.20      mycroft   792:                        bcopy((caddr_t)&ia->ia_addr.sin_addr,
1.1       cgd       793:                            (caddr_t)(cp + off), sizeof(struct in_addr));
                    794:                        cp[IPOPT_OFFSET] += sizeof(struct in_addr);
                    795:                        break;
                    796:
                    797:                case IPOPT_TS:
                    798:                        code = cp - (u_char *)ip;
                    799:                        ipt = (struct ip_timestamp *)cp;
                    800:                        if (ipt->ipt_len < 5)
                    801:                                goto bad;
1.15      cgd       802:                        if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
1.1       cgd       803:                                if (++ipt->ipt_oflw == 0)
                    804:                                        goto bad;
                    805:                                break;
                    806:                        }
                    807:                        sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
                    808:                        switch (ipt->ipt_flg) {
                    809:
                    810:                        case IPOPT_TS_TSONLY:
                    811:                                break;
                    812:
                    813:                        case IPOPT_TS_TSANDADDR:
                    814:                                if (ipt->ipt_ptr + sizeof(n_time) +
                    815:                                    sizeof(struct in_addr) > ipt->ipt_len)
                    816:                                        goto bad;
1.13      mycroft   817:                                ipaddr.sin_addr = dst;
                    818:                                ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
                    819:                                                            m->m_pkthdr.rcvif);
                    820:                                if (ia == 0)
                    821:                                        continue;
1.20      mycroft   822:                                bcopy((caddr_t)&ia->ia_addr.sin_addr,
1.1       cgd       823:                                    (caddr_t)sin, sizeof(struct in_addr));
                    824:                                ipt->ipt_ptr += sizeof(struct in_addr);
                    825:                                break;
                    826:
                    827:                        case IPOPT_TS_PRESPEC:
                    828:                                if (ipt->ipt_ptr + sizeof(n_time) +
                    829:                                    sizeof(struct in_addr) > ipt->ipt_len)
                    830:                                        goto bad;
                    831:                                bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
                    832:                                    sizeof(struct in_addr));
                    833:                                if (ifa_ifwithaddr((SA)&ipaddr) == 0)
                    834:                                        continue;
                    835:                                ipt->ipt_ptr += sizeof(struct in_addr);
                    836:                                break;
                    837:
                    838:                        default:
                    839:                                goto bad;
                    840:                        }
                    841:                        ntime = iptime();
                    842:                        bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
                    843:                            sizeof(n_time));
                    844:                        ipt->ipt_ptr += sizeof(n_time);
                    845:                }
                    846:        }
                    847:        if (forward) {
1.26      thorpej   848:                if (ip_forwsrcrt == 0) {
                    849:                        type = ICMP_UNREACH;
                    850:                        code = ICMP_UNREACH_SRCFAIL;
                    851:                        goto bad;
                    852:                }
1.1       cgd       853:                ip_forward(m, 1);
                    854:                return (1);
1.13      mycroft   855:        }
                    856:        return (0);
1.1       cgd       857: bad:
1.13      mycroft   858:        ip->ip_len -= ip->ip_hl << 2;   /* XXX icmp_error adds in hdr length */
                    859:        icmp_error(m, type, code, 0, 0);
                    860:        ipstat.ips_badoptions++;
1.1       cgd       861:        return (1);
                    862: }
                    863:
                    864: /*
                    865:  * Given address of next destination (final or next hop),
                    866:  * return internet address info of interface to be used to get there.
                    867:  */
                    868: struct in_ifaddr *
                    869: ip_rtaddr(dst)
                    870:         struct in_addr dst;
                    871: {
                    872:        register struct sockaddr_in *sin;
                    873:
1.19      mycroft   874:        sin = satosin(&ipforward_rt.ro_dst);
1.1       cgd       875:
1.35      mycroft   876:        if (ipforward_rt.ro_rt == 0 || !in_hosteq(dst, sin->sin_addr)) {
1.1       cgd       877:                if (ipforward_rt.ro_rt) {
                    878:                        RTFREE(ipforward_rt.ro_rt);
                    879:                        ipforward_rt.ro_rt = 0;
                    880:                }
                    881:                sin->sin_family = AF_INET;
                    882:                sin->sin_len = sizeof(*sin);
                    883:                sin->sin_addr = dst;
                    884:
                    885:                rtalloc(&ipforward_rt);
                    886:        }
                    887:        if (ipforward_rt.ro_rt == 0)
                    888:                return ((struct in_ifaddr *)0);
1.19      mycroft   889:        return (ifatoia(ipforward_rt.ro_rt->rt_ifa));
1.1       cgd       890: }
                    891:
                    892: /*
                    893:  * Save incoming source route for use in replies,
                    894:  * to be picked up later by ip_srcroute if the receiver is interested.
                    895:  */
1.13      mycroft   896: void
1.1       cgd       897: save_rte(option, dst)
                    898:        u_char *option;
                    899:        struct in_addr dst;
                    900: {
                    901:        unsigned olen;
                    902:
                    903:        olen = option[IPOPT_OLEN];
                    904: #ifdef DIAGNOSTIC
                    905:        if (ipprintfs)
1.39      christos  906:                printf("save_rte: olen %d\n", olen);
1.1       cgd       907: #endif
                    908:        if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
                    909:                return;
                    910:        bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen);
                    911:        ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
                    912:        ip_srcrt.dst = dst;
                    913: }
                    914:
                    915: /*
                    916:  * Retrieve incoming source route for use in replies,
                    917:  * in the same form used by setsockopt.
                    918:  * The first hop is placed before the options, will be removed later.
                    919:  */
                    920: struct mbuf *
                    921: ip_srcroute()
                    922: {
                    923:        register struct in_addr *p, *q;
                    924:        register struct mbuf *m;
                    925:
                    926:        if (ip_nhops == 0)
                    927:                return ((struct mbuf *)0);
                    928:        m = m_get(M_DONTWAIT, MT_SOOPTS);
                    929:        if (m == 0)
                    930:                return ((struct mbuf *)0);
                    931:
1.13      mycroft   932: #define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
1.1       cgd       933:
                    934:        /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
                    935:        m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
                    936:            OPTSIZ;
                    937: #ifdef DIAGNOSTIC
                    938:        if (ipprintfs)
1.39      christos  939:                printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
1.1       cgd       940: #endif
                    941:
                    942:        /*
                    943:         * First save first hop for return route
                    944:         */
                    945:        p = &ip_srcrt.route[ip_nhops - 1];
                    946:        *(mtod(m, struct in_addr *)) = *p--;
                    947: #ifdef DIAGNOSTIC
                    948:        if (ipprintfs)
1.39      christos  949:                printf(" hops %x", ntohl(mtod(m, struct in_addr *)->s_addr));
1.1       cgd       950: #endif
                    951:
                    952:        /*
                    953:         * Copy option fields and padding (nop) to mbuf.
                    954:         */
                    955:        ip_srcrt.nop = IPOPT_NOP;
                    956:        ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
                    957:        bcopy((caddr_t)&ip_srcrt.nop,
                    958:            mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ);
                    959:        q = (struct in_addr *)(mtod(m, caddr_t) +
                    960:            sizeof(struct in_addr) + OPTSIZ);
                    961: #undef OPTSIZ
                    962:        /*
                    963:         * Record return path as an IP source route,
                    964:         * reversing the path (pointers are now aligned).
                    965:         */
                    966:        while (p >= ip_srcrt.route) {
                    967: #ifdef DIAGNOSTIC
                    968:                if (ipprintfs)
1.39      christos  969:                        printf(" %x", ntohl(q->s_addr));
1.1       cgd       970: #endif
                    971:                *q++ = *p--;
                    972:        }
                    973:        /*
                    974:         * Last hop goes to final destination.
                    975:         */
                    976:        *q = ip_srcrt.dst;
                    977: #ifdef DIAGNOSTIC
                    978:        if (ipprintfs)
1.39      christos  979:                printf(" %x\n", ntohl(q->s_addr));
1.1       cgd       980: #endif
                    981:        return (m);
                    982: }
                    983:
                    984: /*
                    985:  * Strip out IP options, at higher
                    986:  * level protocol in the kernel.
                    987:  * Second argument is buffer to which options
                    988:  * will be moved, and return value is their length.
                    989:  * XXX should be deleted; last arg currently ignored.
                    990:  */
1.8       mycroft   991: void
1.1       cgd       992: ip_stripoptions(m, mopt)
                    993:        register struct mbuf *m;
                    994:        struct mbuf *mopt;
                    995: {
                    996:        register int i;
                    997:        struct ip *ip = mtod(m, struct ip *);
                    998:        register caddr_t opts;
                    999:        int olen;
                   1000:
                   1001:        olen = (ip->ip_hl<<2) - sizeof (struct ip);
                   1002:        opts = (caddr_t)(ip + 1);
                   1003:        i = m->m_len - (sizeof (struct ip) + olen);
                   1004:        bcopy(opts  + olen, opts, (unsigned)i);
                   1005:        m->m_len -= olen;
                   1006:        if (m->m_flags & M_PKTHDR)
                   1007:                m->m_pkthdr.len -= olen;
                   1008:        ip->ip_hl = sizeof(struct ip) >> 2;
                   1009: }
                   1010:
1.23      mycroft  1011: int inetctlerrmap[PRC_NCMDS] = {
1.1       cgd      1012:        0,              0,              0,              0,
                   1013:        0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
                   1014:        EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
                   1015:        EMSGSIZE,       EHOSTUNREACH,   0,              0,
                   1016:        0,              0,              0,              0,
                   1017:        ENOPROTOOPT
                   1018: };
                   1019:
                   1020: /*
                   1021:  * Forward a packet.  If some error occurs return the sender
                   1022:  * an icmp packet.  Note we can't always generate a meaningful
                   1023:  * icmp message because icmp doesn't have a large enough repertoire
                   1024:  * of codes and types.
                   1025:  *
                   1026:  * If not forwarding, just drop the packet.  This could be confusing
                   1027:  * if ipforwarding was zero but some routing protocol was advancing
                   1028:  * us as a gateway to somewhere.  However, we must let the routing
                   1029:  * protocol deal with that.
                   1030:  *
                   1031:  * The srcrt parameter indicates whether the packet is being forwarded
                   1032:  * via a source route.
                   1033:  */
1.13      mycroft  1034: void
1.1       cgd      1035: ip_forward(m, srcrt)
                   1036:        struct mbuf *m;
                   1037:        int srcrt;
                   1038: {
                   1039:        register struct ip *ip = mtod(m, struct ip *);
                   1040:        register struct sockaddr_in *sin;
                   1041:        register struct rtentry *rt;
1.28      christos 1042:        int error, type = 0, code = 0;
1.1       cgd      1043:        struct mbuf *mcopy;
1.13      mycroft  1044:        n_long dest;
                   1045:        struct ifnet *destifp;
1.1       cgd      1046:
1.13      mycroft  1047:        dest = 0;
1.1       cgd      1048: #ifdef DIAGNOSTIC
                   1049:        if (ipprintfs)
1.39      christos 1050:                printf("forward: src %x dst %x ttl %x\n",
1.35      mycroft  1051:                    ip->ip_src.s_addr, ip->ip_dst.s_addr, ip->ip_ttl);
1.1       cgd      1052: #endif
                   1053:        if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) {
                   1054:                ipstat.ips_cantforward++;
                   1055:                m_freem(m);
                   1056:                return;
                   1057:        }
                   1058:        HTONS(ip->ip_id);
                   1059:        if (ip->ip_ttl <= IPTTLDEC) {
1.13      mycroft  1060:                icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
1.1       cgd      1061:                return;
                   1062:        }
                   1063:        ip->ip_ttl -= IPTTLDEC;
                   1064:
1.19      mycroft  1065:        sin = satosin(&ipforward_rt.ro_dst);
1.1       cgd      1066:        if ((rt = ipforward_rt.ro_rt) == 0 ||
1.35      mycroft  1067:            !in_hosteq(ip->ip_dst, sin->sin_addr)) {
1.1       cgd      1068:                if (ipforward_rt.ro_rt) {
                   1069:                        RTFREE(ipforward_rt.ro_rt);
                   1070:                        ipforward_rt.ro_rt = 0;
                   1071:                }
                   1072:                sin->sin_family = AF_INET;
1.35      mycroft  1073:                sin->sin_len = sizeof(struct sockaddr_in);
1.1       cgd      1074:                sin->sin_addr = ip->ip_dst;
                   1075:
                   1076:                rtalloc(&ipforward_rt);
                   1077:                if (ipforward_rt.ro_rt == 0) {
1.13      mycroft  1078:                        icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
1.1       cgd      1079:                        return;
                   1080:                }
                   1081:                rt = ipforward_rt.ro_rt;
                   1082:        }
                   1083:
                   1084:        /*
1.34      mycroft  1085:         * Save at most 68 bytes of the packet in case
1.1       cgd      1086:         * we need to generate an ICMP message to the src.
                   1087:         */
1.34      mycroft  1088:        mcopy = m_copy(m, 0, imin((int)ip->ip_len, 68));
1.1       cgd      1089:
                   1090:        /*
                   1091:         * If forwarding packet using same interface that it came in on,
                   1092:         * perhaps should send a redirect to sender to shortcut a hop.
                   1093:         * Only send redirect if source is sending directly to us,
                   1094:         * and if packet was not source routed (or has any options).
                   1095:         * Also, don't send redirect if forwarding using a default route
                   1096:         * or a route modified by a redirect.
                   1097:         */
                   1098:        if (rt->rt_ifp == m->m_pkthdr.rcvif &&
                   1099:            (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1.35      mycroft  1100:            !in_nullhost(satosin(rt_key(rt))->sin_addr) &&
1.1       cgd      1101:            ipsendredirects && !srcrt) {
1.19      mycroft  1102:                if (rt->rt_ifa &&
                   1103:                    (ip->ip_src.s_addr & ifatoia(rt->rt_ifa)->ia_subnetmask) ==
                   1104:                    ifatoia(rt->rt_ifa)->ia_subnet) {
1.1       cgd      1105:                    if (rt->rt_flags & RTF_GATEWAY)
1.13      mycroft  1106:                        dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
1.1       cgd      1107:                    else
1.13      mycroft  1108:                        dest = ip->ip_dst.s_addr;
                   1109:                    /* Router requirements says to only send host redirects */
1.1       cgd      1110:                    type = ICMP_REDIRECT;
1.13      mycroft  1111:                    code = ICMP_REDIRECT_HOST;
1.1       cgd      1112: #ifdef DIAGNOSTIC
                   1113:                    if (ipprintfs)
1.39      christos 1114:                        printf("redirect (%d) to %x\n", code, (u_int32_t)dest);
1.1       cgd      1115: #endif
                   1116:                }
                   1117:        }
                   1118:
1.27      thorpej  1119:        error = ip_output(m, (struct mbuf *)0, &ipforward_rt,
                   1120:            (IP_FORWARDING | (ip_directedbcast ? IP_ALLOWBROADCAST : 0)), 0);
1.1       cgd      1121:        if (error)
                   1122:                ipstat.ips_cantforward++;
                   1123:        else {
                   1124:                ipstat.ips_forward++;
                   1125:                if (type)
                   1126:                        ipstat.ips_redirectsent++;
                   1127:                else {
                   1128:                        if (mcopy)
                   1129:                                m_freem(mcopy);
                   1130:                        return;
                   1131:                }
                   1132:        }
                   1133:        if (mcopy == NULL)
                   1134:                return;
1.13      mycroft  1135:        destifp = NULL;
                   1136:
1.1       cgd      1137:        switch (error) {
                   1138:
                   1139:        case 0:                         /* forwarded, but need redirect */
                   1140:                /* type, code set above */
                   1141:                break;
                   1142:
                   1143:        case ENETUNREACH:               /* shouldn't happen, checked above */
                   1144:        case EHOSTUNREACH:
                   1145:        case ENETDOWN:
                   1146:        case EHOSTDOWN:
                   1147:        default:
                   1148:                type = ICMP_UNREACH;
                   1149:                code = ICMP_UNREACH_HOST;
                   1150:                break;
                   1151:
                   1152:        case EMSGSIZE:
                   1153:                type = ICMP_UNREACH;
                   1154:                code = ICMP_UNREACH_NEEDFRAG;
1.13      mycroft  1155:                if (ipforward_rt.ro_rt)
                   1156:                        destifp = ipforward_rt.ro_rt->rt_ifp;
1.1       cgd      1157:                ipstat.ips_cantfrag++;
                   1158:                break;
                   1159:
                   1160:        case ENOBUFS:
                   1161:                type = ICMP_SOURCEQUENCH;
                   1162:                code = 0;
                   1163:                break;
                   1164:        }
1.13      mycroft  1165:        icmp_error(mcopy, type, code, dest, destifp);
1.44    ! thorpej  1166: }
        !          1167:
        !          1168: void
        !          1169: ip_savecontrol(inp, mp, ip, m)
        !          1170:        register struct inpcb *inp;
        !          1171:        register struct mbuf **mp;
        !          1172:        register struct ip *ip;
        !          1173:        register struct mbuf *m;
        !          1174: {
        !          1175:
        !          1176:        if (inp->inp_socket->so_options & SO_TIMESTAMP) {
        !          1177:                struct timeval tv;
        !          1178:
        !          1179:                microtime(&tv);
        !          1180:                *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
        !          1181:                    SCM_TIMESTAMP, SOL_SOCKET);
        !          1182:                if (*mp)
        !          1183:                        mp = &(*mp)->m_next;
        !          1184:        }
        !          1185:        if (inp->inp_flags & INP_RECVDSTADDR) {
        !          1186:                *mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
        !          1187:                    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
        !          1188:                if (*mp)
        !          1189:                        mp = &(*mp)->m_next;
        !          1190:        }
        !          1191: #ifdef notyet
        !          1192:        /*
        !          1193:         * XXX
        !          1194:         * Moving these out of udp_input() made them even more broken
        !          1195:         * than they already were.
        !          1196:         *      - fenner@parc.xerox.com
        !          1197:         */
        !          1198:        /* options were tossed already */
        !          1199:        if (inp->inp_flags & INP_RECVOPTS) {
        !          1200:                *mp = sbcreatecontrol((caddr_t) opts_deleted_above,
        !          1201:                    sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
        !          1202:                if (*mp)
        !          1203:                        mp = &(*mp)->m_next;
        !          1204:        }
        !          1205:        /* ip_srcroute doesn't do what we want here, need to fix */
        !          1206:        if (inp->inp_flags & INP_RECVRETOPTS) {
        !          1207:                *mp = sbcreatecontrol((caddr_t) ip_srcroute(),
        !          1208:                    sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
        !          1209:                if (*mp)
        !          1210:                        mp = &(*mp)->m_next;
        !          1211:        }
        !          1212: #endif
        !          1213:        if (inp->inp_flags & INP_RECVIF) {
        !          1214:                struct sockaddr_dl sdl;
        !          1215:
        !          1216:                sdl.sdl_len = offsetof(struct sockaddr_dl, sdl_data[0]);
        !          1217:                sdl.sdl_family = AF_LINK;
        !          1218:                sdl.sdl_index = m->m_pkthdr.rcvif ?
        !          1219:                    m->m_pkthdr.rcvif->if_index : 0;
        !          1220:                sdl.sdl_nlen = sdl.sdl_alen = sdl.sdl_slen = 0;
        !          1221:                *mp = sbcreatecontrol((caddr_t) &sdl, sdl.sdl_len,
        !          1222:                    IP_RECVIF, IPPROTO_IP);
        !          1223:                if (*mp)
        !          1224:                        mp = &(*mp)->m_next;
        !          1225:        }
1.13      mycroft  1226: }
                   1227:
                   1228: int
                   1229: ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
                   1230:        int *name;
                   1231:        u_int namelen;
                   1232:        void *oldp;
                   1233:        size_t *oldlenp;
                   1234:        void *newp;
                   1235:        size_t newlen;
                   1236: {
                   1237:        /* All sysctl names at this level are terminal. */
                   1238:        if (namelen != 1)
                   1239:                return (ENOTDIR);
                   1240:
                   1241:        switch (name[0]) {
                   1242:        case IPCTL_FORWARDING:
                   1243:                return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding));
                   1244:        case IPCTL_SENDREDIRECTS:
                   1245:                return (sysctl_int(oldp, oldlenp, newp, newlen,
                   1246:                        &ipsendredirects));
                   1247:        case IPCTL_DEFTTL:
                   1248:                return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl));
                   1249: #ifdef notyet
                   1250:        case IPCTL_DEFMTU:
                   1251:                return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu));
                   1252: #endif
1.26      thorpej  1253:        case IPCTL_FORWSRCRT:
                   1254:                /*
                   1255:                 * Don't allow this to change in a secure environment.
                   1256:                 */
                   1257:                if (securelevel > 0)
                   1258:                        return (EPERM);
                   1259:                return (sysctl_int(oldp, oldlenp, newp, newlen,
                   1260:                    &ip_forwsrcrt));
1.27      thorpej  1261:        case IPCTL_DIRECTEDBCAST:
                   1262:                return (sysctl_int(oldp, oldlenp, newp, newlen,
                   1263:                    &ip_directedbcast));
1.13      mycroft  1264:        default:
                   1265:                return (EOPNOTSUPP);
                   1266:        }
                   1267:        /* NOTREACHED */
1.1       cgd      1268: }

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