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Annotation of src/sys/netinet6/frag6.c, Revision 1.10

1.10    ! itojun      1: /*     $NetBSD: frag6.c,v 1.9 2000/02/03 18:13:01 itojun Exp $ */
1.3       thorpej     2:
1.2       itojun      3: /*
                      4:  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
                      5:  * All rights reserved.
                      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. Neither the name of the project nor the names of its contributors
                     16:  *    may be used to endorse or promote products derived from this software
                     17:  *    without specific prior written permission.
                     18:  *
                     19:  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
                     20:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     21:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     22:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
                     23:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     24:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     25:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     26:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     27:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     28:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     29:  * SUCH DAMAGE.
                     30:  */
                     31:
                     32: #include <sys/param.h>
                     33: #include <sys/systm.h>
                     34: #include <sys/malloc.h>
                     35: #include <sys/mbuf.h>
                     36: #include <sys/domain.h>
                     37: #include <sys/protosw.h>
                     38: #include <sys/socket.h>
                     39: #include <sys/errno.h>
                     40: #include <sys/time.h>
                     41: #include <sys/kernel.h>
                     42: #include <sys/syslog.h>
                     43:
                     44: #include <net/if.h>
                     45: #include <net/route.h>
                     46:
                     47: #include <netinet/in.h>
                     48: #include <netinet/in_var.h>
1.10    ! itojun     49: #include <netinet/ip6.h>
1.2       itojun     50: #include <netinet6/in6_pcb.h>
                     51: #include <netinet6/ip6_var.h>
1.10    ! itojun     52: #include <netinet/icmp6.h>
1.2       itojun     53:
1.7       itojun     54: #include <net/net_osdep.h>
                     55:
                     56: /*
                     57:  * Define it to get a correct behavior on per-interface statistics.
                     58:  * You will need to perform an extra routing table lookup, per fragment,
                     59:  * to do it.  This may, or may not be, a performance hit.
                     60:  */
                     61: #define IN6_IFSTAT_STRICT
                     62:
1.2       itojun     63: static void frag6_enq __P((struct ip6asfrag *, struct ip6asfrag *));
                     64: static void frag6_deq __P((struct ip6asfrag *));
                     65: static void frag6_insque __P((struct ip6q *, struct ip6q *));
                     66: static void frag6_remque __P((struct ip6q *));
                     67: static void frag6_freef __P((struct ip6q *));
                     68:
                     69: int frag6_doing_reass;
                     70: u_int frag6_nfragpackets;
                     71: struct ip6q ip6q;      /* ip6 reassemble queue */
                     72:
1.9       itojun     73: #ifndef offsetof               /* XXX */
                     74: #define        offsetof(type, member)  ((size_t)(&((type *)0)->member))
                     75: #endif
                     76:
1.2       itojun     77: /*
                     78:  * Initialise reassembly queue and fragment identifier.
                     79:  */
                     80: void
                     81: frag6_init()
                     82: {
1.6       itojun     83:        struct timeval tv;
                     84:
                     85:        /*
                     86:         * in many cases, random() here does NOT return random number
                     87:         * as initialization during bootstrap time occur in fixed order.
                     88:         */
                     89:        microtime(&tv);
1.9       itojun     90:        ip6_id = random() ^ tv.tv_usec;
1.2       itojun     91:        ip6q.ip6q_next = ip6q.ip6q_prev = &ip6q;
                     92: }
                     93:
                     94: /*
1.9       itojun     95:  * In RFC2460, fragment and reassembly rule do not agree with each other,
                     96:  * in terms of next header field handling in fragment header.
                     97:  * While the sender will use the same value for all of the fragmented packets,
                     98:  * receiver is suggested not to check the consistency.
                     99:  *
                    100:  * fragment rule (p20):
                    101:  *     (2) A Fragment header containing:
                    102:  *     The Next Header value that identifies the first header of
                    103:  *     the Fragmentable Part of the original packet.
                    104:  *             -> next header field is same for all fragments
                    105:  *
                    106:  * reassembly rule (p21):
                    107:  *     The Next Header field of the last header of the Unfragmentable
                    108:  *     Part is obtained from the Next Header field of the first
                    109:  *     fragment's Fragment header.
                    110:  *             -> should grab it from the first fragment only
                    111:  *
                    112:  * The following note also contradicts with fragment rule - noone is going to
                    113:  * send different fragment with different next header field.
                    114:  *
                    115:  * additional note (p22):
                    116:  *     The Next Header values in the Fragment headers of different
                    117:  *     fragments of the same original packet may differ.  Only the value
                    118:  *     from the Offset zero fragment packet is used for reassembly.
                    119:  *             -> should grab it from the first fragment only
                    120:  *
                    121:  * There is no explicit reason given in the RFC.  Historical reason maybe?
                    122:  */
                    123: /*
1.2       itojun    124:  * Fragment input
                    125:  */
                    126: int
                    127: frag6_input(mp, offp, proto)
                    128:        struct mbuf **mp;
                    129:        int *offp, proto;
                    130: {
                    131:        struct mbuf *m = *mp, *t;
                    132:        struct ip6_hdr *ip6;
                    133:        struct ip6_frag *ip6f;
                    134:        struct ip6q *q6;
1.9       itojun    135:        struct ip6asfrag *af6, *ip6af, *af6dwn;
1.2       itojun    136:        int offset = *offp, nxt, i, next;
                    137:        int first_frag = 0;
1.9       itojun    138:        int fragoff, frgpartlen;        /* must be larger than u_int16_t */
1.7       itojun    139:        struct ifnet *dstifp;
                    140: #ifdef IN6_IFSTAT_STRICT
                    141:        static struct route_in6 ro;
                    142:        struct sockaddr_in6 *dst;
                    143: #endif
1.2       itojun    144:
1.7       itojun    145:        ip6 = mtod(m, struct ip6_hdr *);
                    146: #ifndef PULLDOWN_TEST
1.2       itojun    147:        IP6_EXTHDR_CHECK(m, offset, sizeof(struct ip6_frag), IPPROTO_DONE);
1.7       itojun    148:        ip6f = (struct ip6_frag *)((caddr_t)ip6 + offset);
                    149: #else
                    150:        IP6_EXTHDR_GET(ip6f, struct ip6_frag *, m, offset, sizeof(*ip6f));
                    151:        if (ip6f == NULL)
                    152:                return IPPROTO_DONE;
                    153: #endif
1.2       itojun    154:
1.7       itojun    155:        dstifp = NULL;
                    156: #ifdef IN6_IFSTAT_STRICT
                    157:        /* find the destination interface of the packet. */
                    158:        dst = (struct sockaddr_in6 *)&ro.ro_dst;
                    159:        if (ro.ro_rt
                    160:         && ((ro.ro_rt->rt_flags & RTF_UP) == 0
                    161:          || !IN6_ARE_ADDR_EQUAL(&dst->sin6_addr, &ip6->ip6_dst))) {
                    162:                RTFREE(ro.ro_rt);
                    163:                ro.ro_rt = (struct rtentry *)0;
                    164:        }
                    165:        if (ro.ro_rt == NULL) {
                    166:                bzero(dst, sizeof(*dst));
                    167:                dst->sin6_family = AF_INET6;
                    168:                dst->sin6_len = sizeof(struct sockaddr_in6);
                    169:                dst->sin6_addr = ip6->ip6_dst;
                    170:        }
                    171:        rtalloc((struct route *)&ro);
                    172:        if (ro.ro_rt != NULL && ro.ro_rt->rt_ifa != NULL)
                    173:                dstifp = ((struct in6_ifaddr *)ro.ro_rt->rt_ifa)->ia_ifp;
                    174: #else
                    175:        /* we are violating the spec, this is not the destination interface */
                    176:        if ((m->m_flags & M_PKTHDR) != 0)
                    177:                dstifp = m->m_pkthdr.rcvif;
                    178: #endif
1.2       itojun    179:
                    180:        /* jumbo payload can't contain a fragment header */
                    181:        if (ip6->ip6_plen == 0) {
                    182:                icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offset);
1.7       itojun    183:                in6_ifstat_inc(dstifp, ifs6_reass_fail);
1.2       itojun    184:                return IPPROTO_DONE;
                    185:        }
                    186:
                    187:        /*
                    188:         * check whether fragment packet's fragment length is
                    189:         * multiple of 8 octets.
                    190:         * sizeof(struct ip6_frag) == 8
                    191:         * sizeof(struct ip6_hdr) = 40
                    192:         */
                    193:        if ((ip6f->ip6f_offlg & IP6F_MORE_FRAG) &&
                    194:            (((ntohs(ip6->ip6_plen) - offset) & 0x7) != 0)) {
                    195:                icmp6_error(m, ICMP6_PARAM_PROB,
                    196:                            ICMP6_PARAMPROB_HEADER,
1.9       itojun    197:                            offsetof(struct ip6_hdr, ip6_plen));
1.7       itojun    198:                in6_ifstat_inc(dstifp, ifs6_reass_fail);
1.2       itojun    199:                return IPPROTO_DONE;
                    200:        }
                    201:
                    202:        ip6stat.ip6s_fragments++;
1.7       itojun    203:        in6_ifstat_inc(dstifp, ifs6_reass_reqd);
1.2       itojun    204:
1.9       itojun    205:        /* offset now points to data portion */
1.2       itojun    206:        offset += sizeof(struct ip6_frag);
                    207:
                    208:        for (q6 = ip6q.ip6q_next; q6 != &ip6q; q6 = q6->ip6q_next)
                    209:                if (ip6f->ip6f_ident == q6->ip6q_ident &&
                    210:                    IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &q6->ip6q_src) &&
                    211:                    IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &q6->ip6q_dst))
                    212:                        break;
                    213:
                    214:        if (q6 == &ip6q) {
                    215:                /*
                    216:                 * the first fragment to arrive, create a reassembly queue.
                    217:                 */
                    218:                first_frag = 1;
                    219:                frag6_nfragpackets++;
                    220:
                    221:                /*
                    222:                 * Enforce upper bound on number of fragmented packets
                    223:                 * for which we attempt reassembly;
                    224:                 * If maxfrag is 0, never accept fragments.
                    225:                 * If maxfrag is -1, accept all fragments without limitation.
                    226:                 */
                    227:                if (frag6_nfragpackets >= (u_int)ip6_maxfragpackets) {
                    228:                        ip6stat.ip6s_fragoverflow++;
1.7       itojun    229:                        in6_ifstat_inc(dstifp, ifs6_reass_fail);
1.2       itojun    230:                        frag6_freef(ip6q.ip6q_prev);
                    231:                }
                    232:                q6 = (struct ip6q *)malloc(sizeof(struct ip6q), M_FTABLE,
                    233:                        M_DONTWAIT);
                    234:                if (q6 == NULL)
                    235:                        goto dropfrag;
1.9       itojun    236:                bzero(q6, sizeof(*q6));
1.2       itojun    237:
                    238:                frag6_insque(q6, &ip6q);
                    239:
1.9       itojun    240:                /* ip6q_nxt will be filled afterwards, from 1st fragment */
1.2       itojun    241:                q6->ip6q_down   = q6->ip6q_up = (struct ip6asfrag *)q6;
                    242: #ifdef notyet
                    243:                q6->ip6q_nxtp   = (u_char *)nxtp;
                    244: #endif
                    245:                q6->ip6q_ident  = ip6f->ip6f_ident;
                    246:                q6->ip6q_arrive = 0; /* Is it used anywhere? */
                    247:                q6->ip6q_ttl    = IPV6_FRAGTTL;
                    248:                q6->ip6q_src    = ip6->ip6_src;
                    249:                q6->ip6q_dst    = ip6->ip6_dst;
                    250:                q6->ip6q_unfrglen = -1; /* The 1st fragment has not arrived. */
                    251:        }
                    252:
                    253:        /*
                    254:         * If it's the 1st fragment, record the length of the
                    255:         * unfragmentable part and the next header of the fragment header.
                    256:         */
                    257:        fragoff = ntohs(ip6f->ip6f_offlg & IP6F_OFF_MASK);
                    258:        if (fragoff == 0) {
                    259:                q6->ip6q_unfrglen = offset - sizeof(struct ip6_hdr)
                    260:                        - sizeof(struct ip6_frag);
                    261:                q6->ip6q_nxt = ip6f->ip6f_nxt;
                    262:        }
                    263:
                    264:        /*
                    265:         * Check that the reassembled packet would not exceed 65535 bytes
                    266:         * in size.
                    267:         * If it would exceed, discard the fragment and return an ICMP error.
                    268:         */
1.9       itojun    269:        frgpartlen = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen) - offset;
1.2       itojun    270:        if (q6->ip6q_unfrglen >= 0) {
                    271:                /* The 1st fragment has already arrived. */
                    272:                if (q6->ip6q_unfrglen + fragoff + frgpartlen > IPV6_MAXPACKET) {
                    273:                        icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
1.9       itojun    274:                                    offset - sizeof(struct ip6_frag) +
                    275:                                        offsetof(struct ip6_frag, ip6f_offlg));
1.2       itojun    276:                        return(IPPROTO_DONE);
                    277:                }
                    278:        }
                    279:        else if (fragoff + frgpartlen > IPV6_MAXPACKET) {
                    280:                icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER,
1.9       itojun    281:                            offset - sizeof(struct ip6_frag) +
                    282:                                offsetof(struct ip6_frag, ip6f_offlg));
1.2       itojun    283:                return(IPPROTO_DONE);
                    284:        }
                    285:        /*
                    286:         * If it's the first fragment, do the above check for each
                    287:         * fragment already stored in the reassembly queue.
                    288:         */
                    289:        if (fragoff == 0) {
                    290:                for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
                    291:                     af6 = af6dwn) {
                    292:                        af6dwn = af6->ip6af_down;
                    293:
                    294:                        if (q6->ip6q_unfrglen + af6->ip6af_off + af6->ip6af_frglen >
                    295:                            IPV6_MAXPACKET) {
                    296:                                struct mbuf *merr = IP6_REASS_MBUF(af6);
                    297:                                struct ip6_hdr *ip6err;
                    298:                                int erroff = af6->ip6af_offset;
                    299:
                    300:                                /* dequeue the fragment. */
                    301:                                frag6_deq(af6);
1.9       itojun    302:                                free(af6, M_FTABLE);
1.2       itojun    303:
                    304:                                /* adjust pointer. */
                    305:                                ip6err = mtod(merr, struct ip6_hdr *);
                    306:
                    307:                                /*
                    308:                                 * Restore source and destination addresses
                    309:                                 * in the erroneous IPv6 header.
                    310:                                 */
                    311:                                ip6err->ip6_src = q6->ip6q_src;
                    312:                                ip6err->ip6_dst = q6->ip6q_dst;
                    313:
                    314:                                icmp6_error(merr, ICMP6_PARAM_PROB,
                    315:                                            ICMP6_PARAMPROB_HEADER,
1.9       itojun    316:                                            erroff - sizeof(struct ip6_frag) +
                    317:                                                offsetof(struct ip6_frag, ip6f_offlg));
1.2       itojun    318:                        }
                    319:                }
                    320:        }
                    321:
1.9       itojun    322:        ip6af = (struct ip6asfrag *)malloc(sizeof(struct ip6asfrag), M_FTABLE,
                    323:            M_DONTWAIT);
                    324:        if (ip6af == NULL)
                    325:                goto dropfrag;
                    326:        bzero(ip6af, sizeof(*ip6af));
                    327:        ip6af->ip6af_head = ip6->ip6_flow;
                    328:        ip6af->ip6af_len = ip6->ip6_plen;
                    329:        ip6af->ip6af_nxt = ip6->ip6_nxt;
                    330:        ip6af->ip6af_hlim = ip6->ip6_hlim;
1.2       itojun    331:        ip6af->ip6af_mff = ip6f->ip6f_offlg & IP6F_MORE_FRAG;
                    332:        ip6af->ip6af_off = fragoff;
                    333:        ip6af->ip6af_frglen = frgpartlen;
                    334:        ip6af->ip6af_offset = offset;
                    335:        IP6_REASS_MBUF(ip6af) = m;
                    336:
                    337:        if (first_frag) {
                    338:                af6 = (struct ip6asfrag *)q6;
                    339:                goto insert;
                    340:        }
                    341:
                    342:        /*
                    343:         * Find a segment which begins after this one does.
                    344:         */
                    345:        for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
                    346:             af6 = af6->ip6af_down)
                    347:                if (af6->ip6af_off > ip6af->ip6af_off)
                    348:                        break;
                    349:
                    350: #if 0
                    351:        /*
                    352:         * If there is a preceding segment, it may provide some of
                    353:         * our data already.  If so, drop the data from the incoming
                    354:         * segment.  If it provides all of our data, drop us.
                    355:         */
                    356:        if (af6->ip6af_up != (struct ip6asfrag *)q6) {
                    357:                i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
                    358:                        - ip6af->ip6af_off;
                    359:                if (i > 0) {
                    360:                        if (i >= ip6af->ip6af_frglen)
                    361:                                goto dropfrag;
                    362:                        m_adj(IP6_REASS_MBUF(ip6af), i);
                    363:                        ip6af->ip6af_off += i;
                    364:                        ip6af->ip6af_frglen -= i;
                    365:                }
                    366:        }
                    367:
                    368:        /*
                    369:         * While we overlap succeeding segments trim them or,
                    370:         * if they are completely covered, dequeue them.
                    371:         */
                    372:        while (af6 != (struct ip6asfrag *)q6 &&
                    373:               ip6af->ip6af_off + ip6af->ip6af_frglen > af6->ip6af_off) {
                    374:                i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
                    375:                if (i < af6->ip6af_frglen) {
                    376:                        af6->ip6af_frglen -= i;
                    377:                        af6->ip6af_off += i;
                    378:                        m_adj(IP6_REASS_MBUF(af6), i);
                    379:                        break;
                    380:                }
                    381:                af6 = af6->ip6af_down;
                    382:                m_freem(IP6_REASS_MBUF(af6->ip6af_up));
                    383:                frag6_deq(af6->ip6af_up);
                    384:        }
                    385: #else
                    386:        /*
                    387:         * If the incoming framgent overlaps some existing fragments in
                    388:         * the reassembly queue, drop it, since it is dangerous to override
                    389:         * existing fragments from a security point of view.
                    390:         */
                    391:        if (af6->ip6af_up != (struct ip6asfrag *)q6) {
                    392:                i = af6->ip6af_up->ip6af_off + af6->ip6af_up->ip6af_frglen
                    393:                        - ip6af->ip6af_off;
                    394:                if (i > 0) {
                    395:                        log(LOG_ERR, "%d bytes of a fragment from %s "
                    396:                            "overlaps the previous fragment\n",
                    397:                            i, ip6_sprintf(&q6->ip6q_src));
                    398:                        goto dropfrag;
                    399:                }
                    400:        }
                    401:        if (af6 != (struct ip6asfrag *)q6) {
                    402:                i = (ip6af->ip6af_off + ip6af->ip6af_frglen) - af6->ip6af_off;
                    403:                if (i > 0) {
                    404:                        log(LOG_ERR, "%d bytes of a fragment from %s "
                    405:                            "overlaps the succeeding fragment",
                    406:                            i, ip6_sprintf(&q6->ip6q_src));
                    407:                        goto dropfrag;
                    408:                }
                    409:        }
                    410: #endif
                    411:
                    412: insert:
                    413:
                    414:        /*
                    415:         * Stick new segment in its place;
                    416:         * check for complete reassembly.
                    417:         * Move to front of packet queue, as we are
                    418:         * the most recently active fragmented packet.
                    419:         */
                    420:        frag6_enq(ip6af, af6->ip6af_up);
                    421: #if 0 /* xxx */
                    422:        if (q6 != ip6q.ip6q_next) {
                    423:                frag6_remque(q6);
                    424:                frag6_insque(q6, &ip6q);
                    425:        }
                    426: #endif
                    427:        next = 0;
                    428:        for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
                    429:             af6 = af6->ip6af_down) {
                    430:                if (af6->ip6af_off != next) {
                    431:                        frag6_doing_reass = 0;
                    432:                        return IPPROTO_DONE;
                    433:                }
                    434:                next += af6->ip6af_frglen;
                    435:        }
                    436:        if (af6->ip6af_up->ip6af_mff) {
                    437:                frag6_doing_reass = 0;
                    438:                return IPPROTO_DONE;
                    439:        }
                    440:
                    441:        /*
                    442:         * Reassembly is complete; concatenate fragments.
                    443:         */
                    444:        ip6af = q6->ip6q_down;
                    445:        t = m = IP6_REASS_MBUF(ip6af);
                    446:        af6 = ip6af->ip6af_down;
1.9       itojun    447:        frag6_deq(ip6af);
1.2       itojun    448:        while (af6 != (struct ip6asfrag *)q6) {
1.9       itojun    449:                af6dwn = af6->ip6af_down;
                    450:                frag6_deq(af6);
1.2       itojun    451:                while (t->m_next)
                    452:                        t = t->m_next;
                    453:                t->m_next = IP6_REASS_MBUF(af6);
1.9       itojun    454:                m_adj(t->m_next, af6->ip6af_offset);
                    455:                free(af6, M_FTABLE);
                    456:                af6 = af6dwn;
1.2       itojun    457:        }
                    458:
                    459:        /* adjust offset to point where the original next header starts */
                    460:        offset = ip6af->ip6af_offset - sizeof(struct ip6_frag);
1.9       itojun    461:        free(ip6af, M_FTABLE);
                    462:        ip6 = mtod(m, struct ip6_hdr *);
1.2       itojun    463:        ip6->ip6_plen = htons((u_short)next + offset - sizeof(struct ip6_hdr));
                    464:        ip6->ip6_src = q6->ip6q_src;
                    465:        ip6->ip6_dst = q6->ip6q_dst;
                    466:        nxt = q6->ip6q_nxt;
                    467: #ifdef notyet
                    468:        *q6->ip6q_nxtp = (u_char)(nxt & 0xff);
                    469: #endif
                    470:
                    471:        /*
                    472:         * Delete frag6 header with as a few cost as possible.
                    473:         */
1.9       itojun    474:        if (offset < m->m_len) {
1.7       itojun    475:                ovbcopy((caddr_t)ip6, (caddr_t)ip6 + sizeof(struct ip6_frag),
1.2       itojun    476:                        offset);
1.9       itojun    477:                m->m_data += sizeof(struct ip6_frag);
                    478:                m->m_len -= sizeof(struct ip6_frag);
                    479:        } else {
                    480:                /* this comes with no copy if the boundary is on cluster */
                    481:                if ((t = m_split(m, offset, M_DONTWAIT)) == NULL) {
                    482:                        frag6_remque(q6);
                    483:                        free(q6, M_FTABLE);
                    484:                        frag6_nfragpackets--;
                    485:                        goto dropfrag;
                    486:                }
                    487:                m_adj(t, sizeof(struct ip6_frag));
                    488:                m_cat(m, t);
1.2       itojun    489:        }
                    490:
                    491:        /*
                    492:         * Store NXT to the original.
                    493:         */
                    494:        {
                    495:                char *prvnxtp = ip6_get_prevhdr(m, offset); /* XXX */
                    496:                *prvnxtp = nxt;
                    497:        }
                    498:
                    499:        frag6_remque(q6);
                    500:        free(q6, M_FTABLE);
                    501:        frag6_nfragpackets--;
                    502:
                    503:        if (m->m_flags & M_PKTHDR) { /* Isn't it always true? */
                    504:                int plen = 0;
                    505:                for (t = m; t; t = t->m_next)
                    506:                        plen += t->m_len;
                    507:                m->m_pkthdr.len = plen;
                    508:        }
                    509:
                    510:        ip6stat.ip6s_reassembled++;
1.7       itojun    511:        in6_ifstat_inc(dstifp, ifs6_reass_ok);
1.2       itojun    512:
                    513:        /*
                    514:         * Tell launch routine the next header
                    515:         */
                    516:
                    517:        *mp = m;
                    518:        *offp = offset;
                    519:
                    520:        frag6_doing_reass = 0;
                    521:        return nxt;
                    522:
                    523:  dropfrag:
1.7       itojun    524:        in6_ifstat_inc(dstifp, ifs6_reass_fail);
1.2       itojun    525:        ip6stat.ip6s_fragdropped++;
                    526:        m_freem(m);
                    527:        return IPPROTO_DONE;
                    528: }
                    529:
                    530: /*
                    531:  * Free a fragment reassembly header and all
                    532:  * associated datagrams.
                    533:  */
                    534: void
                    535: frag6_freef(q6)
                    536:        struct ip6q *q6;
                    537: {
                    538:        struct ip6asfrag *af6, *down6;
                    539:
                    540:        for (af6 = q6->ip6q_down; af6 != (struct ip6asfrag *)q6;
                    541:             af6 = down6) {
                    542:                struct mbuf *m = IP6_REASS_MBUF(af6);
                    543:
                    544:                down6 = af6->ip6af_down;
                    545:                frag6_deq(af6);
                    546:
                    547:                /*
                    548:                 * Return ICMP time exceeded error for the 1st fragment.
                    549:                 * Just free other fragments.
                    550:                 */
                    551:                if (af6->ip6af_off == 0) {
                    552:                        struct ip6_hdr *ip6;
                    553:
                    554:                        /* adjust pointer */
                    555:                        ip6 = mtod(m, struct ip6_hdr *);
                    556:
                    557:                        /* restoure source and destination addresses */
                    558:                        ip6->ip6_src = q6->ip6q_src;
                    559:                        ip6->ip6_dst = q6->ip6q_dst;
                    560:
                    561:                        icmp6_error(m, ICMP6_TIME_EXCEEDED,
                    562:                                    ICMP6_TIME_EXCEED_REASSEMBLY, 0);
1.9       itojun    563:                } else
1.2       itojun    564:                        m_freem(m);
1.9       itojun    565:                free(af6, M_FTABLE);
1.2       itojun    566:        }
                    567:        frag6_remque(q6);
                    568:        free(q6, M_FTABLE);
                    569:        frag6_nfragpackets--;
                    570: }
                    571:
                    572: /*
                    573:  * Put an ip fragment on a reassembly chain.
                    574:  * Like insque, but pointers in middle of structure.
                    575:  */
                    576: void
                    577: frag6_enq(af6, up6)
                    578:        struct ip6asfrag *af6, *up6;
                    579: {
                    580:        af6->ip6af_up = up6;
                    581:        af6->ip6af_down = up6->ip6af_down;
                    582:        up6->ip6af_down->ip6af_up = af6;
                    583:        up6->ip6af_down = af6;
                    584: }
                    585:
                    586: /*
                    587:  * To frag6_enq as remque is to insque.
                    588:  */
                    589: void
                    590: frag6_deq(af6)
                    591:        struct ip6asfrag *af6;
                    592: {
                    593:        af6->ip6af_up->ip6af_down = af6->ip6af_down;
                    594:        af6->ip6af_down->ip6af_up = af6->ip6af_up;
                    595: }
                    596:
                    597: void
                    598: frag6_insque(new, old)
                    599:        struct ip6q *new, *old;
                    600: {
                    601:        new->ip6q_prev = old;
                    602:        new->ip6q_next = old->ip6q_next;
                    603:        old->ip6q_next->ip6q_prev= new;
                    604:        old->ip6q_next = new;
                    605: }
                    606:
                    607: void
                    608: frag6_remque(p6)
                    609:        struct ip6q *p6;
                    610: {
                    611:        p6->ip6q_prev->ip6q_next = p6->ip6q_next;
                    612:        p6->ip6q_next->ip6q_prev = p6->ip6q_prev;
                    613: }
                    614:
                    615: /*
                    616:  * IP timer processing;
                    617:  * if a timer expires on a reassembly
                    618:  * queue, discard it.
                    619:  */
                    620: void
                    621: frag6_slowtimo()
                    622: {
                    623:        struct ip6q *q6;
1.4       itojun    624:        int s = splsoftnet();
1.2       itojun    625: #if 0
                    626:        extern struct   route_in6 ip6_forward_rt;
                    627: #endif
                    628:
                    629:        frag6_doing_reass = 1;
                    630:        q6 = ip6q.ip6q_next;
                    631:        if (q6)
                    632:                while (q6 != &ip6q) {
                    633:                        --q6->ip6q_ttl;
                    634:                        q6 = q6->ip6q_next;
                    635:                        if (q6->ip6q_prev->ip6q_ttl == 0) {
                    636:                                ip6stat.ip6s_fragtimeout++;
1.7       itojun    637:                                /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
1.2       itojun    638:                                frag6_freef(q6->ip6q_prev);
                    639:                        }
                    640:                }
                    641:        /*
                    642:         * If we are over the maximum number of fragments
                    643:         * (due to the limit being lowered), drain off
                    644:         * enough to get down to the new limit.
                    645:         */
                    646:        while (frag6_nfragpackets > (u_int)ip6_maxfragpackets) {
                    647:                ip6stat.ip6s_fragoverflow++;
1.7       itojun    648:                /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
1.2       itojun    649:                frag6_freef(ip6q.ip6q_prev);
                    650:        }
                    651:        frag6_doing_reass = 0;
                    652:
                    653: #if 0
                    654:        /*
                    655:         * Routing changes might produce a better route than we last used;
                    656:         * make sure we notice eventually, even if forwarding only for one
                    657:         * destination and the cache is never replaced.
                    658:         */
                    659:        if (ip6_forward_rt.ro_rt) {
                    660:                RTFREE(ip6_forward_rt.ro_rt);
                    661:                ip6_forward_rt.ro_rt = 0;
                    662:        }
                    663:        if (ipsrcchk_rt.ro_rt) {
                    664:                RTFREE(ipsrcchk_rt.ro_rt);
                    665:                ipsrcchk_rt.ro_rt = 0;
                    666:        }
                    667: #endif
                    668:
                    669:        splx(s);
                    670: }
                    671:
                    672: /*
                    673:  * Drain off all datagram fragments.
                    674:  */
                    675: void
                    676: frag6_drain()
                    677: {
                    678:        if (frag6_doing_reass)
                    679:                return;
                    680:        while (ip6q.ip6q_next != &ip6q) {
                    681:                ip6stat.ip6s_fragdropped++;
1.7       itojun    682:                /* XXX in6_ifstat_inc(ifp, ifs6_reass_fail) */
1.2       itojun    683:                frag6_freef(ip6q.ip6q_next);
                    684:        }
                    685: }

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