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Annotation of src/sys/netinet/ip_input.c, Revision 1.1.1.1

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

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