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Annotation of src/sys/netinet/ip_input.c, Revision 1.9

1.1       cgd         1: /*
                      2:  * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
                      3:  * All rights reserved.
                      4:  *
                      5:  * Redistribution and use in source and binary forms, with or without
                      6:  * modification, are permitted provided that the following conditions
                      7:  * are met:
                      8:  * 1. Redistributions of source code must retain the above copyright
                      9:  *    notice, this list of conditions and the following disclaimer.
                     10:  * 2. Redistributions in binary form must reproduce the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer in the
                     12:  *    documentation and/or other materials provided with the distribution.
                     13:  * 3. All advertising materials mentioning features or use of this software
                     14:  *    must display the following acknowledgement:
                     15:  *     This product includes software developed by the University of
                     16:  *     California, Berkeley and its contributors.
                     17:  * 4. Neither the name of the University nor the names of its contributors
                     18:  *    may be used to endorse or promote products derived from this software
                     19:  *    without specific prior written permission.
                     20:  *
                     21:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     22:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     23:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     24:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     25:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     26:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     27:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     28:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     29:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     30:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     31:  * SUCH DAMAGE.
                     32:  *
1.3       cgd        33:  *     from: @(#)ip_input.c    7.19 (Berkeley) 5/25/91
1.9     ! mycroft    34:  *     $Id: ip_input.c,v 1.8 1994/01/09 01:06:13 mycroft Exp $
1.1       cgd        35:  */
                     36:
1.5       mycroft    37: #include <sys/param.h>
                     38: #include <sys/systm.h>
                     39: #include <sys/malloc.h>
                     40: #include <sys/mbuf.h>
                     41: #include <sys/domain.h>
                     42: #include <sys/protosw.h>
                     43: #include <sys/socket.h>
                     44: #include <sys/errno.h>
                     45: #include <sys/time.h>
                     46: #include <sys/kernel.h>
1.1       cgd        47:
1.5       mycroft    48: #include <net/if.h>
                     49: #include <net/route.h>
1.1       cgd        50:
1.5       mycroft    51: #include <netinet/in.h>
                     52: #include <netinet/in_systm.h>
                     53: #include <netinet/ip.h>
                     54: #include <netinet/in_pcb.h>
                     55: #include <netinet/in_var.h>
                     56: #include <netinet/ip_var.h>
                     57: #include <netinet/ip_icmp.h>
1.8       mycroft    58: #include <netinet/ip_mroute.h>
1.1       cgd        59:
                     60: #ifndef        IPFORWARDING
                     61: #ifdef GATEWAY
                     62: #define        IPFORWARDING    1       /* forward IP packets not for us */
                     63: #else /* GATEWAY */
                     64: #define        IPFORWARDING    0       /* don't forward IP packets not for us */
                     65: #endif /* GATEWAY */
                     66: #endif /* IPFORWARDING */
                     67: #ifndef        IPSENDREDIRECTS
                     68: #define        IPSENDREDIRECTS 1
                     69: #endif
                     70: int    ipforwarding = IPFORWARDING;
                     71: int    ipsendredirects = IPSENDREDIRECTS;
                     72: #ifdef DIAGNOSTIC
                     73: int    ipprintfs = 0;
                     74: #endif
                     75:
                     76: extern struct domain inetdomain;
                     77: extern struct protosw inetsw[];
                     78: u_char ip_protox[IPPROTO_MAX];
                     79: int    ipqmaxlen = IFQ_MAXLEN;
                     80: struct in_ifaddr *in_ifaddr;                   /* first inet address */
                     81:
                     82: /*
                     83:  * We need to save the IP options in case a protocol wants to respond
                     84:  * to an incoming packet over the same route if the packet got here
                     85:  * using IP source routing.  This allows connection establishment and
                     86:  * maintenance when the remote end is on a network that is not known
                     87:  * to us.
                     88:  */
                     89: int    ip_nhops = 0;
                     90: static struct ip_srcrt {
                     91:        struct  in_addr dst;                    /* final destination */
                     92:        char    nop;                            /* one NOP to align */
                     93:        char    srcopt[IPOPT_OFFSET + 1];       /* OPTVAL, OLEN and OFFSET */
                     94:        struct  in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
                     95: } ip_srcrt;
                     96:
                     97: #ifdef GATEWAY
                     98: extern int if_index;
                     99: u_long *ip_ifmatrix;
                    100: #endif
                    101:
1.8       mycroft   102: static void    ip_forward __P((struct mbuf *, int));
                    103: static void    save_rte __P((u_char *, struct in_addr));
                    104:
1.1       cgd       105: /*
                    106:  * IP initialization: fill in IP protocol switch table.
                    107:  * All protocols not implemented in kernel go to raw IP protocol handler.
                    108:  */
1.8       mycroft   109: void
1.1       cgd       110: ip_init()
                    111: {
                    112:        register struct protosw *pr;
                    113:        register int i;
                    114:
                    115:        pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
                    116:        if (pr == 0)
                    117:                panic("ip_init");
                    118:        for (i = 0; i < IPPROTO_MAX; i++)
                    119:                ip_protox[i] = pr - inetsw;
                    120:        for (pr = inetdomain.dom_protosw;
                    121:            pr < inetdomain.dom_protoswNPROTOSW; pr++)
                    122:                if (pr->pr_domain->dom_family == PF_INET &&
                    123:                    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
                    124:                        ip_protox[pr->pr_protocol] = pr - inetsw;
                    125:        ipq.next = ipq.prev = &ipq;
                    126:        ip_id = time.tv_sec & 0xffff;
                    127:        ipintrq.ifq_maxlen = ipqmaxlen;
                    128: #ifdef GATEWAY
                    129:        i = (if_index + 1) * (if_index + 1) * sizeof (u_long);
                    130:        if ((ip_ifmatrix = (u_long *) malloc(i, M_RTABLE, M_WAITOK)) == 0)
                    131:                panic("no memory for ip_ifmatrix");
                    132: #endif
                    133: }
                    134:
                    135: struct ip *ip_reass();
                    136: struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
                    137: struct route ipforward_rt;
                    138:
                    139: /*
                    140:  * Ip input routine.  Checksum and byte swap header.  If fragmented
                    141:  * try to reassemble.  Process options.  Pass to next level.
                    142:  */
1.8       mycroft   143: void
1.1       cgd       144: ipintr()
                    145: {
                    146:        register struct ip *ip;
                    147:        register struct mbuf *m;
                    148:        register struct ipq *fp;
                    149:        register struct in_ifaddr *ia;
                    150:        int hlen, s;
1.2       cgd       151: #ifdef PARANOID
                    152:        static int busy = 0;
1.1       cgd       153:
1.2       cgd       154:        if (busy)
                    155:                panic("ipintr: called recursively\n");
                    156:        ++busy;
                    157: #endif
1.1       cgd       158: next:
                    159:        /*
                    160:         * Get next datagram off input queue and get IP header
                    161:         * in first mbuf.
                    162:         */
                    163:        s = splimp();
                    164:        IF_DEQUEUE(&ipintrq, m);
                    165:        splx(s);
1.2       cgd       166:        if (m == 0) {
                    167: #ifdef PARANOID
                    168:                --busy;
                    169: #endif
1.1       cgd       170:                return;
1.2       cgd       171:        }
1.1       cgd       172: #ifdef DIAGNOSTIC
                    173:        if ((m->m_flags & M_PKTHDR) == 0)
                    174:                panic("ipintr no HDR");
                    175: #endif
                    176:        /*
                    177:         * If no IP addresses have been set yet but the interfaces
                    178:         * are receiving, can't do anything with incoming packets yet.
                    179:         */
                    180:        if (in_ifaddr == NULL)
                    181:                goto bad;
                    182:        ipstat.ips_total++;
                    183:        if (m->m_len < sizeof (struct ip) &&
                    184:            (m = m_pullup(m, sizeof (struct ip))) == 0) {
                    185:                ipstat.ips_toosmall++;
                    186:                goto next;
                    187:        }
                    188:        ip = mtod(m, struct ip *);
                    189:        hlen = ip->ip_hl << 2;
                    190:        if (hlen < sizeof(struct ip)) { /* minimum header length */
                    191:                ipstat.ips_badhlen++;
                    192:                goto bad;
                    193:        }
                    194:        if (hlen > m->m_len) {
                    195:                if ((m = m_pullup(m, hlen)) == 0) {
                    196:                        ipstat.ips_badhlen++;
                    197:                        goto next;
                    198:                }
                    199:                ip = mtod(m, struct ip *);
                    200:        }
                    201:        if (ip->ip_sum = in_cksum(m, hlen)) {
                    202:                ipstat.ips_badsum++;
                    203:                goto bad;
                    204:        }
                    205:
                    206:        /*
                    207:         * Convert fields to host representation.
                    208:         */
                    209:        NTOHS(ip->ip_len);
                    210:        if (ip->ip_len < hlen) {
                    211:                ipstat.ips_badlen++;
                    212:                goto bad;
                    213:        }
                    214:        NTOHS(ip->ip_id);
                    215:        NTOHS(ip->ip_off);
                    216:
                    217:        /*
                    218:         * Check that the amount of data in the buffers
                    219:         * is as at least much as the IP header would have us expect.
                    220:         * Trim mbufs if longer than we expect.
                    221:         * Drop packet if shorter than we expect.
                    222:         */
                    223:        if (m->m_pkthdr.len < ip->ip_len) {
                    224:                ipstat.ips_tooshort++;
                    225:                goto bad;
                    226:        }
                    227:        if (m->m_pkthdr.len > ip->ip_len) {
                    228:                if (m->m_len == m->m_pkthdr.len) {
                    229:                        m->m_len = ip->ip_len;
                    230:                        m->m_pkthdr.len = ip->ip_len;
                    231:                } else
                    232:                        m_adj(m, ip->ip_len - m->m_pkthdr.len);
                    233:        }
                    234:
                    235:        /*
                    236:         * Process options and, if not destined for us,
                    237:         * ship it on.  ip_dooptions returns 1 when an
                    238:         * error was detected (causing an icmp message
                    239:         * to be sent and the original packet to be freed).
                    240:         */
                    241:        ip_nhops = 0;           /* for source routed packets */
                    242:        if (hlen > sizeof (struct ip) && ip_dooptions(m))
                    243:                goto next;
                    244:
                    245:        /*
                    246:         * Check our list of addresses, to see if the packet is for us.
                    247:         */
                    248:        for (ia = in_ifaddr; ia; ia = ia->ia_next) {
                    249: #define        satosin(sa)     ((struct sockaddr_in *)(sa))
                    250:
                    251:                if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
                    252:                        goto ours;
                    253:                if (
                    254: #ifdef DIRECTED_BROADCAST
                    255:                    ia->ia_ifp == m->m_pkthdr.rcvif &&
                    256: #endif
                    257:                    (ia->ia_ifp->if_flags & IFF_BROADCAST)) {
                    258:                        u_long t;
                    259:
                    260:                        if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
                    261:                            ip->ip_dst.s_addr)
                    262:                                goto ours;
                    263:                        if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr)
                    264:                                goto ours;
                    265:                        /*
                    266:                         * Look for all-0's host part (old broadcast addr),
                    267:                         * either for subnet or net.
                    268:                         */
                    269:                        t = ntohl(ip->ip_dst.s_addr);
                    270:                        if (t == ia->ia_subnet)
                    271:                                goto ours;
                    272:                        if (t == ia->ia_net)
                    273:                                goto ours;
                    274:                }
                    275:        }
1.4       hpeyerl   276: #ifdef MULTICAST
                    277:        if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
                    278:                struct in_multi *inm;
                    279: #ifdef MROUTING
                    280:                extern struct socket *ip_mrouter;
                    281:
                    282:                if (ip_mrouter) {
                    283:                        /*
                    284:                         * If we are acting as a multicast router, all
                    285:                         * incoming multicast packets are passed to the
                    286:                         * kernel-level multicast forwarding function.
                    287:                         * The packet is returned (relatively) intact; if
                    288:                         * ip_mforward() returns a non-zero value, the packet
                    289:                         * must be discarded, else it may be accepted below.
                    290:                         *
                    291:                         * (The IP ident field is put in the same byte order
                    292:                         * as expected when ip_mforward() is called from
                    293:                         * ip_output().)
                    294:                         */
                    295:                        ip->ip_id = htons(ip->ip_id);
                    296:                        if (ip_mforward(ip, m->m_pkthdr.rcvif, m) != 0) {
                    297:                                m_freem(m);
                    298:                                goto next;
                    299:                        }
                    300:                        ip->ip_id = ntohs(ip->ip_id);
                    301:
                    302:                        /*
                    303:                         * The process-level routing demon needs to receive
                    304:                         * all multicast IGMP packets, whether or not this
                    305:                         * host belongs to their destination groups.
                    306:                         */
                    307:                        if (ip->ip_p == IPPROTO_IGMP)
                    308:                                goto ours;
                    309:                }
                    310: #endif
                    311:                /*
                    312:                 * See if we belong to the destination multicast group on the
                    313:                 * arrival interface.
                    314:                 */
                    315:                IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
                    316:                if (inm == NULL) {
                    317:                        m_freem(m);
                    318:                        goto next;
                    319:                }
                    320:                goto ours;
                    321:        }
                    322: #endif
1.1       cgd       323:        if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
                    324:                goto ours;
                    325:        if (ip->ip_dst.s_addr == INADDR_ANY)
                    326:                goto ours;
                    327:
                    328:        /*
                    329:         * Not for us; forward if possible and desirable.
                    330:         */
                    331:        if (ipforwarding == 0) {
                    332:                ipstat.ips_cantforward++;
                    333:                m_freem(m);
                    334:        } else
                    335:                ip_forward(m, 0);
                    336:        goto next;
                    337:
                    338: ours:
                    339:        /*
                    340:         * If offset or IP_MF are set, must reassemble.
                    341:         * Otherwise, nothing need be done.
                    342:         * (We could look in the reassembly queue to see
                    343:         * if the packet was previously fragmented,
                    344:         * but it's not worth the time; just let them time out.)
                    345:         */
                    346:        if (ip->ip_off &~ IP_DF) {
                    347:                if (m->m_flags & M_EXT) {               /* XXX */
                    348:                        if ((m = m_pullup(m, sizeof (struct ip))) == 0) {
                    349:                                ipstat.ips_toosmall++;
                    350:                                goto next;
                    351:                        }
                    352:                        ip = mtod(m, struct ip *);
                    353:                }
                    354:                /*
                    355:                 * Look for queue of fragments
                    356:                 * of this datagram.
                    357:                 */
                    358:                for (fp = ipq.next; fp != &ipq; fp = fp->next)
                    359:                        if (ip->ip_id == fp->ipq_id &&
                    360:                            ip->ip_src.s_addr == fp->ipq_src.s_addr &&
                    361:                            ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
                    362:                            ip->ip_p == fp->ipq_p)
                    363:                                goto found;
                    364:                fp = 0;
                    365: found:
                    366:
                    367:                /*
                    368:                 * Adjust ip_len to not reflect header,
                    369:                 * set ip_mff if more fragments are expected,
                    370:                 * convert offset of this to bytes.
                    371:                 */
                    372:                ip->ip_len -= hlen;
                    373:                ((struct ipasfrag *)ip)->ipf_mff = 0;
                    374:                if (ip->ip_off & IP_MF)
                    375:                        ((struct ipasfrag *)ip)->ipf_mff = 1;
                    376:                ip->ip_off <<= 3;
                    377:
                    378:                /*
                    379:                 * If datagram marked as having more fragments
                    380:                 * or if this is not the first fragment,
                    381:                 * attempt reassembly; if it succeeds, proceed.
                    382:                 */
                    383:                if (((struct ipasfrag *)ip)->ipf_mff || ip->ip_off) {
                    384:                        ipstat.ips_fragments++;
                    385:                        ip = ip_reass((struct ipasfrag *)ip, fp);
                    386:                        if (ip == 0)
                    387:                                goto next;
                    388:                        else
                    389:                                ipstat.ips_reassembled++;
                    390:                        m = dtom(ip);
                    391:                } else
                    392:                        if (fp)
                    393:                                ip_freef(fp);
                    394:        } else
                    395:                ip->ip_len -= hlen;
                    396:
                    397:        /*
                    398:         * Switch out to protocol's input routine.
                    399:         */
                    400:        ipstat.ips_delivered++;
                    401:        (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
                    402:        goto next;
                    403: bad:
                    404:        m_freem(m);
                    405:        goto next;
                    406: }
                    407:
                    408: /*
                    409:  * Take incoming datagram fragment and try to
                    410:  * reassemble it into whole datagram.  If a chain for
                    411:  * reassembly of this datagram already exists, then it
                    412:  * is given as fp; otherwise have to make a chain.
                    413:  */
                    414: struct ip *
                    415: ip_reass(ip, fp)
                    416:        register struct ipasfrag *ip;
                    417:        register struct ipq *fp;
                    418: {
                    419:        register struct mbuf *m = dtom(ip);
                    420:        register struct ipasfrag *q;
                    421:        struct mbuf *t;
                    422:        int hlen = ip->ip_hl << 2;
                    423:        int i, next;
                    424:
                    425:        /*
                    426:         * Presence of header sizes in mbufs
                    427:         * would confuse code below.
                    428:         */
                    429:        m->m_data += hlen;
                    430:        m->m_len -= hlen;
                    431:
                    432:        /*
                    433:         * If first fragment to arrive, create a reassembly queue.
                    434:         */
                    435:        if (fp == 0) {
                    436:                if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
                    437:                        goto dropfrag;
                    438:                fp = mtod(t, struct ipq *);
                    439:                insque(fp, &ipq);
                    440:                fp->ipq_ttl = IPFRAGTTL;
                    441:                fp->ipq_p = ip->ip_p;
                    442:                fp->ipq_id = ip->ip_id;
                    443:                fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp;
                    444:                fp->ipq_src = ((struct ip *)ip)->ip_src;
                    445:                fp->ipq_dst = ((struct ip *)ip)->ip_dst;
                    446:                q = (struct ipasfrag *)fp;
                    447:                goto insert;
                    448:        }
                    449:
                    450:        /*
                    451:         * Find a segment which begins after this one does.
                    452:         */
                    453:        for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next)
                    454:                if (q->ip_off > ip->ip_off)
                    455:                        break;
                    456:
                    457:        /*
                    458:         * If there is a preceding segment, it may provide some of
                    459:         * our data already.  If so, drop the data from the incoming
                    460:         * segment.  If it provides all of our data, drop us.
                    461:         */
                    462:        if (q->ipf_prev != (struct ipasfrag *)fp) {
                    463:                i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off;
                    464:                if (i > 0) {
                    465:                        if (i >= ip->ip_len)
                    466:                                goto dropfrag;
                    467:                        m_adj(dtom(ip), i);
                    468:                        ip->ip_off += i;
                    469:                        ip->ip_len -= i;
                    470:                }
                    471:        }
                    472:
                    473:        /*
                    474:         * While we overlap succeeding segments trim them or,
                    475:         * if they are completely covered, dequeue them.
                    476:         */
                    477:        while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) {
                    478:                i = (ip->ip_off + ip->ip_len) - q->ip_off;
                    479:                if (i < q->ip_len) {
                    480:                        q->ip_len -= i;
                    481:                        q->ip_off += i;
                    482:                        m_adj(dtom(q), i);
                    483:                        break;
                    484:                }
                    485:                q = q->ipf_next;
                    486:                m_freem(dtom(q->ipf_prev));
                    487:                ip_deq(q->ipf_prev);
                    488:        }
                    489:
                    490: insert:
                    491:        /*
                    492:         * Stick new segment in its place;
                    493:         * check for complete reassembly.
                    494:         */
                    495:        ip_enq(ip, q->ipf_prev);
                    496:        next = 0;
                    497:        for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) {
                    498:                if (q->ip_off != next)
                    499:                        return (0);
                    500:                next += q->ip_len;
                    501:        }
                    502:        if (q->ipf_prev->ipf_mff)
                    503:                return (0);
                    504:
                    505:        /*
                    506:         * Reassembly is complete; concatenate fragments.
                    507:         */
                    508:        q = fp->ipq_next;
                    509:        m = dtom(q);
                    510:        t = m->m_next;
                    511:        m->m_next = 0;
                    512:        m_cat(m, t);
                    513:        q = q->ipf_next;
                    514:        while (q != (struct ipasfrag *)fp) {
                    515:                t = dtom(q);
                    516:                q = q->ipf_next;
                    517:                m_cat(m, t);
                    518:        }
                    519:
                    520:        /*
                    521:         * Create header for new ip packet by
                    522:         * modifying header of first packet;
                    523:         * dequeue and discard fragment reassembly header.
                    524:         * Make header visible.
                    525:         */
                    526:        ip = fp->ipq_next;
                    527:        ip->ip_len = next;
                    528:        ((struct ip *)ip)->ip_src = fp->ipq_src;
                    529:        ((struct ip *)ip)->ip_dst = fp->ipq_dst;
                    530:        remque(fp);
                    531:        (void) m_free(dtom(fp));
                    532:        m = dtom(ip);
                    533:        m->m_len += (ip->ip_hl << 2);
                    534:        m->m_data -= (ip->ip_hl << 2);
                    535:        /* some debugging cruft by sklower, below, will go away soon */
                    536:        if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
                    537:                register int plen = 0;
                    538:                for (t = m; m; m = m->m_next)
                    539:                        plen += m->m_len;
                    540:                t->m_pkthdr.len = plen;
                    541:        }
                    542:        return ((struct ip *)ip);
                    543:
                    544: dropfrag:
                    545:        ipstat.ips_fragdropped++;
                    546:        m_freem(m);
                    547:        return (0);
                    548: }
                    549:
                    550: /*
                    551:  * Free a fragment reassembly header and all
                    552:  * associated datagrams.
                    553:  */
1.8       mycroft   554: void
1.1       cgd       555: ip_freef(fp)
                    556:        struct ipq *fp;
                    557: {
                    558:        register struct ipasfrag *q, *p;
                    559:
                    560:        for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) {
                    561:                p = q->ipf_next;
                    562:                ip_deq(q);
                    563:                m_freem(dtom(q));
                    564:        }
                    565:        remque(fp);
                    566:        (void) m_free(dtom(fp));
                    567: }
                    568:
                    569: /*
                    570:  * Put an ip fragment on a reassembly chain.
                    571:  * Like insque, but pointers in middle of structure.
                    572:  */
1.8       mycroft   573: void
1.1       cgd       574: ip_enq(p, prev)
                    575:        register struct ipasfrag *p, *prev;
                    576: {
                    577:
                    578:        p->ipf_prev = prev;
                    579:        p->ipf_next = prev->ipf_next;
                    580:        prev->ipf_next->ipf_prev = p;
                    581:        prev->ipf_next = p;
                    582: }
                    583:
                    584: /*
                    585:  * To ip_enq as remque is to insque.
                    586:  */
1.8       mycroft   587: void
1.1       cgd       588: ip_deq(p)
                    589:        register struct ipasfrag *p;
                    590: {
                    591:
                    592:        p->ipf_prev->ipf_next = p->ipf_next;
                    593:        p->ipf_next->ipf_prev = p->ipf_prev;
                    594: }
                    595:
                    596: /*
                    597:  * IP timer processing;
                    598:  * if a timer expires on a reassembly
                    599:  * queue, discard it.
                    600:  */
1.8       mycroft   601: void
1.1       cgd       602: ip_slowtimo()
                    603: {
                    604:        register struct ipq *fp;
                    605:        int s = splnet();
                    606:
                    607:        fp = ipq.next;
                    608:        if (fp == 0) {
                    609:                splx(s);
                    610:                return;
                    611:        }
                    612:        while (fp != &ipq) {
                    613:                --fp->ipq_ttl;
                    614:                fp = fp->next;
                    615:                if (fp->prev->ipq_ttl == 0) {
                    616:                        ipstat.ips_fragtimeout++;
                    617:                        ip_freef(fp->prev);
                    618:                }
                    619:        }
                    620:        splx(s);
                    621: }
                    622:
                    623: /*
                    624:  * Drain off all datagram fragments.
                    625:  */
1.8       mycroft   626: void
1.1       cgd       627: ip_drain()
                    628: {
                    629:
                    630:        while (ipq.next != &ipq) {
                    631:                ipstat.ips_fragdropped++;
                    632:                ip_freef(ipq.next);
                    633:        }
                    634: }
                    635:
                    636: extern struct in_ifaddr *ifptoia();
                    637: struct in_ifaddr *ip_rtaddr();
                    638:
                    639: /*
                    640:  * Do option processing on a datagram,
                    641:  * possibly discarding it if bad options are encountered,
                    642:  * or forwarding it if source-routed.
                    643:  * Returns 1 if packet has been forwarded/freed,
                    644:  * 0 if the packet should be processed further.
                    645:  */
1.8       mycroft   646: int
1.1       cgd       647: ip_dooptions(m)
                    648:        struct mbuf *m;
                    649: {
                    650:        register struct ip *ip = mtod(m, struct ip *);
                    651:        register u_char *cp;
                    652:        register struct ip_timestamp *ipt;
                    653:        register struct in_ifaddr *ia;
                    654:        int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
                    655:        struct in_addr *sin;
                    656:        n_time ntime;
                    657:
                    658:        cp = (u_char *)(ip + 1);
                    659:        cnt = (ip->ip_hl << 2) - sizeof (struct ip);
                    660:        for (; cnt > 0; cnt -= optlen, cp += optlen) {
                    661:                opt = cp[IPOPT_OPTVAL];
                    662:                if (opt == IPOPT_EOL)
                    663:                        break;
                    664:                if (opt == IPOPT_NOP)
                    665:                        optlen = 1;
                    666:                else {
                    667:                        optlen = cp[IPOPT_OLEN];
                    668:                        if (optlen <= 0 || optlen > cnt) {
                    669:                                code = &cp[IPOPT_OLEN] - (u_char *)ip;
                    670:                                goto bad;
                    671:                        }
                    672:                }
                    673:                switch (opt) {
                    674:
                    675:                default:
                    676:                        break;
                    677:
                    678:                /*
                    679:                 * Source routing with record.
                    680:                 * Find interface with current destination address.
                    681:                 * If none on this machine then drop if strictly routed,
                    682:                 * or do nothing if loosely routed.
                    683:                 * Record interface address and bring up next address
                    684:                 * component.  If strictly routed make sure next
                    685:                 * address is on directly accessible net.
                    686:                 */
                    687:                case IPOPT_LSRR:
                    688:                case IPOPT_SSRR:
                    689:                        if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
                    690:                                code = &cp[IPOPT_OFFSET] - (u_char *)ip;
                    691:                                goto bad;
                    692:                        }
                    693:                        ipaddr.sin_addr = ip->ip_dst;
                    694:                        ia = (struct in_ifaddr *)
                    695:                                ifa_ifwithaddr((struct sockaddr *)&ipaddr);
                    696:                        if (ia == 0) {
                    697:                                if (opt == IPOPT_SSRR) {
                    698:                                        type = ICMP_UNREACH;
                    699:                                        code = ICMP_UNREACH_SRCFAIL;
                    700:                                        goto bad;
                    701:                                }
                    702:                                /*
                    703:                                 * Loose routing, and not at next destination
                    704:                                 * yet; nothing to do except forward.
                    705:                                 */
                    706:                                break;
                    707:                        }
                    708:                        off--;                  /* 0 origin */
                    709:                        if (off > optlen - sizeof(struct in_addr)) {
                    710:                                /*
                    711:                                 * End of source route.  Should be for us.
                    712:                                 */
                    713:                                save_rte(cp, ip->ip_src);
                    714:                                break;
                    715:                        }
                    716:                        /*
                    717:                         * locate outgoing interface
                    718:                         */
                    719:                        bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
                    720:                            sizeof(ipaddr.sin_addr));
                    721:                        if (opt == IPOPT_SSRR) {
                    722: #define        INA     struct in_ifaddr *
                    723: #define        SA      struct sockaddr *
                    724:                            if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
                    725:                                ia = in_iaonnetof(in_netof(ipaddr.sin_addr));
                    726:                        } else
                    727:                                ia = ip_rtaddr(ipaddr.sin_addr);
                    728:                        if (ia == 0) {
                    729:                                type = ICMP_UNREACH;
                    730:                                code = ICMP_UNREACH_SRCFAIL;
                    731:                                goto bad;
                    732:                        }
                    733:                        ip->ip_dst = ipaddr.sin_addr;
                    734:                        bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
                    735:                            (caddr_t)(cp + off), sizeof(struct in_addr));
                    736:                        cp[IPOPT_OFFSET] += sizeof(struct in_addr);
                    737:                        forward = 1;
                    738:                        break;
                    739:
                    740:                case IPOPT_RR:
                    741:                        if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
                    742:                                code = &cp[IPOPT_OFFSET] - (u_char *)ip;
                    743:                                goto bad;
                    744:                        }
                    745:                        /*
                    746:                         * If no space remains, ignore.
                    747:                         */
                    748:                        off--;                  /* 0 origin */
                    749:                        if (off > optlen - sizeof(struct in_addr))
                    750:                                break;
                    751:                        bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
                    752:                            sizeof(ipaddr.sin_addr));
                    753:                        /*
                    754:                         * locate outgoing interface; if we're the destination,
                    755:                         * use the incoming interface (should be same).
                    756:                         */
                    757:                        if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
                    758:                            (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
                    759:                                type = ICMP_UNREACH;
                    760:                                code = ICMP_UNREACH_HOST;
                    761:                                goto bad;
                    762:                        }
                    763:                        bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
                    764:                            (caddr_t)(cp + off), sizeof(struct in_addr));
                    765:                        cp[IPOPT_OFFSET] += sizeof(struct in_addr);
                    766:                        break;
                    767:
                    768:                case IPOPT_TS:
                    769:                        code = cp - (u_char *)ip;
                    770:                        ipt = (struct ip_timestamp *)cp;
                    771:                        if (ipt->ipt_len < 5)
                    772:                                goto bad;
                    773:                        if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) {
                    774:                                if (++ipt->ipt_oflw == 0)
                    775:                                        goto bad;
                    776:                                break;
                    777:                        }
                    778:                        sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
                    779:                        switch (ipt->ipt_flg) {
                    780:
                    781:                        case IPOPT_TS_TSONLY:
                    782:                                break;
                    783:
                    784:                        case IPOPT_TS_TSANDADDR:
                    785:                                if (ipt->ipt_ptr + sizeof(n_time) +
                    786:                                    sizeof(struct in_addr) > ipt->ipt_len)
                    787:                                        goto bad;
                    788:                                ia = ifptoia(m->m_pkthdr.rcvif);
                    789:                                bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
                    790:                                    (caddr_t)sin, sizeof(struct in_addr));
                    791:                                ipt->ipt_ptr += sizeof(struct in_addr);
                    792:                                break;
                    793:
                    794:                        case IPOPT_TS_PRESPEC:
                    795:                                if (ipt->ipt_ptr + sizeof(n_time) +
                    796:                                    sizeof(struct in_addr) > ipt->ipt_len)
                    797:                                        goto bad;
                    798:                                bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
                    799:                                    sizeof(struct in_addr));
                    800:                                if (ifa_ifwithaddr((SA)&ipaddr) == 0)
                    801:                                        continue;
                    802:                                ipt->ipt_ptr += sizeof(struct in_addr);
                    803:                                break;
                    804:
                    805:                        default:
                    806:                                goto bad;
                    807:                        }
                    808:                        ntime = iptime();
                    809:                        bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
                    810:                            sizeof(n_time));
                    811:                        ipt->ipt_ptr += sizeof(n_time);
                    812:                }
                    813:        }
                    814:        if (forward) {
                    815:                ip_forward(m, 1);
                    816:                return (1);
                    817:        } else
                    818:                return (0);
                    819: bad:
1.7       mycroft   820:     {
                    821:        register struct in_addr foo = {};
                    822:        icmp_error(m, type, code, foo);
                    823:     }
1.1       cgd       824:        return (1);
                    825: }
                    826:
                    827: /*
                    828:  * Given address of next destination (final or next hop),
                    829:  * return internet address info of interface to be used to get there.
                    830:  */
                    831: struct in_ifaddr *
                    832: ip_rtaddr(dst)
                    833:         struct in_addr dst;
                    834: {
                    835:        register struct sockaddr_in *sin;
                    836:
                    837:        sin = (struct sockaddr_in *) &ipforward_rt.ro_dst;
                    838:
                    839:        if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) {
                    840:                if (ipforward_rt.ro_rt) {
                    841:                        RTFREE(ipforward_rt.ro_rt);
                    842:                        ipforward_rt.ro_rt = 0;
                    843:                }
                    844:                sin->sin_family = AF_INET;
                    845:                sin->sin_len = sizeof(*sin);
                    846:                sin->sin_addr = dst;
                    847:
                    848:                rtalloc(&ipforward_rt);
                    849:        }
                    850:        if (ipforward_rt.ro_rt == 0)
                    851:                return ((struct in_ifaddr *)0);
                    852:        return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa);
                    853: }
                    854:
                    855: /*
                    856:  * Save incoming source route for use in replies,
                    857:  * to be picked up later by ip_srcroute if the receiver is interested.
                    858:  */
1.8       mycroft   859: static void
1.1       cgd       860: save_rte(option, dst)
                    861:        u_char *option;
                    862:        struct in_addr dst;
                    863: {
                    864:        unsigned olen;
                    865:
                    866:        olen = option[IPOPT_OLEN];
                    867: #ifdef DIAGNOSTIC
                    868:        if (ipprintfs)
                    869:                printf("save_rte: olen %d\n", olen);
                    870: #endif
                    871:        if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
                    872:                return;
                    873:        bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen);
                    874:        ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
                    875:        ip_srcrt.dst = dst;
                    876: }
                    877:
                    878: /*
                    879:  * Retrieve incoming source route for use in replies,
                    880:  * in the same form used by setsockopt.
                    881:  * The first hop is placed before the options, will be removed later.
                    882:  */
                    883: struct mbuf *
                    884: ip_srcroute()
                    885: {
                    886:        register struct in_addr *p, *q;
                    887:        register struct mbuf *m;
                    888:
                    889:        if (ip_nhops == 0)
                    890:                return ((struct mbuf *)0);
                    891:        m = m_get(M_DONTWAIT, MT_SOOPTS);
                    892:        if (m == 0)
                    893:                return ((struct mbuf *)0);
                    894:
1.6       mycroft   895: #define        OPTSIZ  (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
1.1       cgd       896:
                    897:        /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
                    898:        m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
                    899:            OPTSIZ;
                    900: #ifdef DIAGNOSTIC
                    901:        if (ipprintfs)
                    902:                printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
                    903: #endif
                    904:
                    905:        /*
                    906:         * First save first hop for return route
                    907:         */
                    908:        p = &ip_srcrt.route[ip_nhops - 1];
                    909:        *(mtod(m, struct in_addr *)) = *p--;
                    910: #ifdef DIAGNOSTIC
                    911:        if (ipprintfs)
                    912:                printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr));
                    913: #endif
                    914:
                    915:        /*
                    916:         * Copy option fields and padding (nop) to mbuf.
                    917:         */
                    918:        ip_srcrt.nop = IPOPT_NOP;
                    919:        ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
                    920:        bcopy((caddr_t)&ip_srcrt.nop,
                    921:            mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ);
                    922:        q = (struct in_addr *)(mtod(m, caddr_t) +
                    923:            sizeof(struct in_addr) + OPTSIZ);
                    924: #undef OPTSIZ
                    925:        /*
                    926:         * Record return path as an IP source route,
                    927:         * reversing the path (pointers are now aligned).
                    928:         */
                    929:        while (p >= ip_srcrt.route) {
                    930: #ifdef DIAGNOSTIC
                    931:                if (ipprintfs)
                    932:                        printf(" %lx", ntohl(q->s_addr));
                    933: #endif
                    934:                *q++ = *p--;
                    935:        }
                    936:        /*
                    937:         * Last hop goes to final destination.
                    938:         */
                    939:        *q = ip_srcrt.dst;
                    940: #ifdef DIAGNOSTIC
                    941:        if (ipprintfs)
                    942:                printf(" %lx\n", ntohl(q->s_addr));
                    943: #endif
                    944:        return (m);
                    945: }
                    946:
                    947: /*
                    948:  * Strip out IP options, at higher
                    949:  * level protocol in the kernel.
                    950:  * Second argument is buffer to which options
                    951:  * will be moved, and return value is their length.
                    952:  * XXX should be deleted; last arg currently ignored.
                    953:  */
1.8       mycroft   954: void
1.1       cgd       955: ip_stripoptions(m, mopt)
                    956:        register struct mbuf *m;
                    957:        struct mbuf *mopt;
                    958: {
                    959:        register int i;
                    960:        struct ip *ip = mtod(m, struct ip *);
                    961:        register caddr_t opts;
                    962:        int olen;
                    963:
                    964:        olen = (ip->ip_hl<<2) - sizeof (struct ip);
                    965:        opts = (caddr_t)(ip + 1);
                    966:        i = m->m_len - (sizeof (struct ip) + olen);
                    967:        bcopy(opts  + olen, opts, (unsigned)i);
                    968:        m->m_len -= olen;
                    969:        if (m->m_flags & M_PKTHDR)
                    970:                m->m_pkthdr.len -= olen;
                    971:        ip->ip_hl = sizeof(struct ip) >> 2;
                    972: }
                    973:
                    974: u_char inetctlerrmap[PRC_NCMDS] = {
                    975:        0,              0,              0,              0,
                    976:        0,              EMSGSIZE,       EHOSTDOWN,      EHOSTUNREACH,
                    977:        EHOSTUNREACH,   EHOSTUNREACH,   ECONNREFUSED,   ECONNREFUSED,
                    978:        EMSGSIZE,       EHOSTUNREACH,   0,              0,
                    979:        0,              0,              0,              0,
                    980:        ENOPROTOOPT
                    981: };
                    982:
                    983: /*
                    984:  * Forward a packet.  If some error occurs return the sender
                    985:  * an icmp packet.  Note we can't always generate a meaningful
                    986:  * icmp message because icmp doesn't have a large enough repertoire
                    987:  * of codes and types.
                    988:  *
                    989:  * If not forwarding, just drop the packet.  This could be confusing
                    990:  * if ipforwarding was zero but some routing protocol was advancing
                    991:  * us as a gateway to somewhere.  However, we must let the routing
                    992:  * protocol deal with that.
                    993:  *
                    994:  * The srcrt parameter indicates whether the packet is being forwarded
                    995:  * via a source route.
                    996:  */
1.8       mycroft   997: static void
1.1       cgd       998: ip_forward(m, srcrt)
                    999:        struct mbuf *m;
                   1000:        int srcrt;
                   1001: {
                   1002:        register struct ip *ip = mtod(m, struct ip *);
                   1003:        register struct sockaddr_in *sin;
                   1004:        register struct rtentry *rt;
                   1005:        int error, type = 0, code;
                   1006:        struct mbuf *mcopy;
                   1007:        struct in_addr dest;
                   1008:
                   1009:        dest.s_addr = 0;
                   1010: #ifdef DIAGNOSTIC
                   1011:        if (ipprintfs)
                   1012:                printf("forward: src %x dst %x ttl %x\n", ip->ip_src,
                   1013:                        ip->ip_dst, ip->ip_ttl);
                   1014: #endif
                   1015:        if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) {
                   1016:                ipstat.ips_cantforward++;
                   1017:                m_freem(m);
                   1018:                return;
                   1019:        }
                   1020:        HTONS(ip->ip_id);
                   1021:        if (ip->ip_ttl <= IPTTLDEC) {
                   1022:                icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest);
                   1023:                return;
                   1024:        }
                   1025:        ip->ip_ttl -= IPTTLDEC;
                   1026:
                   1027:        sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
                   1028:        if ((rt = ipforward_rt.ro_rt) == 0 ||
                   1029:            ip->ip_dst.s_addr != sin->sin_addr.s_addr) {
                   1030:                if (ipforward_rt.ro_rt) {
                   1031:                        RTFREE(ipforward_rt.ro_rt);
                   1032:                        ipforward_rt.ro_rt = 0;
                   1033:                }
                   1034:                sin->sin_family = AF_INET;
                   1035:                sin->sin_len = sizeof(*sin);
                   1036:                sin->sin_addr = ip->ip_dst;
                   1037:
                   1038:                rtalloc(&ipforward_rt);
                   1039:                if (ipforward_rt.ro_rt == 0) {
                   1040:                        icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest);
                   1041:                        return;
                   1042:                }
                   1043:                rt = ipforward_rt.ro_rt;
                   1044:        }
                   1045:
                   1046:        /*
                   1047:         * Save at most 64 bytes of the packet in case
                   1048:         * we need to generate an ICMP message to the src.
                   1049:         */
                   1050:        mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64));
                   1051:
                   1052: #ifdef GATEWAY
                   1053:        ip_ifmatrix[rt->rt_ifp->if_index +
                   1054:             if_index * m->m_pkthdr.rcvif->if_index]++;
                   1055: #endif
                   1056:        /*
                   1057:         * If forwarding packet using same interface that it came in on,
                   1058:         * perhaps should send a redirect to sender to shortcut a hop.
                   1059:         * Only send redirect if source is sending directly to us,
                   1060:         * and if packet was not source routed (or has any options).
                   1061:         * Also, don't send redirect if forwarding using a default route
                   1062:         * or a route modified by a redirect.
                   1063:         */
                   1064: #define        satosin(sa)     ((struct sockaddr_in *)(sa))
                   1065:        if (rt->rt_ifp == m->m_pkthdr.rcvif &&
                   1066:            (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
                   1067:            satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
                   1068:            ipsendredirects && !srcrt) {
                   1069:                struct in_ifaddr *ia;
                   1070:                u_long src = ntohl(ip->ip_src.s_addr);
                   1071:                u_long dst = ntohl(ip->ip_dst.s_addr);
                   1072:
                   1073:                if ((ia = ifptoia(m->m_pkthdr.rcvif)) &&
                   1074:                   (src & ia->ia_subnetmask) == ia->ia_subnet) {
                   1075:                    if (rt->rt_flags & RTF_GATEWAY)
                   1076:                        dest = satosin(rt->rt_gateway)->sin_addr;
                   1077:                    else
                   1078:                        dest = ip->ip_dst;
                   1079:                    /*
                   1080:                     * If the destination is reached by a route to host,
                   1081:                     * is on a subnet of a local net, or is directly
                   1082:                     * on the attached net (!), use host redirect.
                   1083:                     * (We may be the correct first hop for other subnets.)
                   1084:                     */
                   1085: #define        RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
                   1086:                    type = ICMP_REDIRECT;
                   1087:                    if ((rt->rt_flags & RTF_HOST) ||
                   1088:                        (rt->rt_flags & RTF_GATEWAY) == 0)
                   1089:                            code = ICMP_REDIRECT_HOST;
                   1090:                    else if (RTA(rt)->ia_subnetmask != RTA(rt)->ia_netmask &&
                   1091:                        (dst & RTA(rt)->ia_netmask) ==  RTA(rt)->ia_net)
                   1092:                            code = ICMP_REDIRECT_HOST;
                   1093:                    else
                   1094:                            code = ICMP_REDIRECT_NET;
                   1095: #ifdef DIAGNOSTIC
                   1096:                    if (ipprintfs)
                   1097:                        printf("redirect (%d) to %x\n", code, dest.s_addr);
                   1098: #endif
                   1099:                }
                   1100:        }
                   1101:
1.9     ! mycroft  1102:        error = ip_output(m, NULL, &ipforward_rt, IP_FORWARDING
        !          1103: #ifdef DIRECTED_BROADCAST
        !          1104:            | IP_ALLOWBROADCAST
        !          1105: #endif
        !          1106:            , NULL);
1.1       cgd      1107:        if (error)
                   1108:                ipstat.ips_cantforward++;
                   1109:        else {
                   1110:                ipstat.ips_forward++;
                   1111:                if (type)
                   1112:                        ipstat.ips_redirectsent++;
                   1113:                else {
                   1114:                        if (mcopy)
                   1115:                                m_freem(mcopy);
                   1116:                        return;
                   1117:                }
                   1118:        }
                   1119:        if (mcopy == NULL)
                   1120:                return;
                   1121:        switch (error) {
                   1122:
                   1123:        case 0:                         /* forwarded, but need redirect */
                   1124:                /* type, code set above */
                   1125:                break;
                   1126:
                   1127:        case ENETUNREACH:               /* shouldn't happen, checked above */
                   1128:        case EHOSTUNREACH:
                   1129:        case ENETDOWN:
                   1130:        case EHOSTDOWN:
                   1131:        default:
                   1132:                type = ICMP_UNREACH;
                   1133:                code = ICMP_UNREACH_HOST;
                   1134:                break;
                   1135:
                   1136:        case EMSGSIZE:
                   1137:                type = ICMP_UNREACH;
                   1138:                code = ICMP_UNREACH_NEEDFRAG;
                   1139:                ipstat.ips_cantfrag++;
                   1140:                break;
                   1141:
                   1142:        case ENOBUFS:
                   1143:                type = ICMP_SOURCEQUENCH;
                   1144:                code = 0;
                   1145:                break;
                   1146:        }
                   1147:        icmp_error(mcopy, type, code, dest);
                   1148: }

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