Annotation of src/sys/netinet/ip_input.c, Revision 1.19
1.19 ! mycroft 1: /* $NetBSD: ip_input.c,v 1.18 1995/06/01 21:36:27 mycroft Exp $ */
1.14 cgd 2:
1.1 cgd 3: /*
1.13 mycroft 4: * Copyright (c) 1982, 1986, 1988, 1993
5: * The Regents of the University of California. All rights reserved.
1.1 cgd 6: *
7: * Redistribution and use in source and binary forms, with or without
8: * modification, are permitted provided that the following conditions
9: * are met:
10: * 1. Redistributions of source code must retain the above copyright
11: * notice, this list of conditions and the following disclaimer.
12: * 2. Redistributions in binary form must reproduce the above copyright
13: * notice, this list of conditions and the following disclaimer in the
14: * documentation and/or other materials provided with the distribution.
15: * 3. All advertising materials mentioning features or use of this software
16: * must display the following acknowledgement:
17: * This product includes software developed by the University of
18: * California, Berkeley and its contributors.
19: * 4. Neither the name of the University nor the names of its contributors
20: * may be used to endorse or promote products derived from this software
21: * without specific prior written permission.
22: *
23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33: * SUCH DAMAGE.
34: *
1.14 cgd 35: * @(#)ip_input.c 8.2 (Berkeley) 1/4/94
1.1 cgd 36: */
37:
1.5 mycroft 38: #include <sys/param.h>
39: #include <sys/systm.h>
40: #include <sys/malloc.h>
41: #include <sys/mbuf.h>
42: #include <sys/domain.h>
43: #include <sys/protosw.h>
44: #include <sys/socket.h>
45: #include <sys/errno.h>
46: #include <sys/time.h>
47: #include <sys/kernel.h>
1.1 cgd 48:
1.5 mycroft 49: #include <net/if.h>
50: #include <net/route.h>
1.1 cgd 51:
1.5 mycroft 52: #include <netinet/in.h>
53: #include <netinet/in_systm.h>
54: #include <netinet/ip.h>
55: #include <netinet/in_pcb.h>
56: #include <netinet/in_var.h>
57: #include <netinet/ip_var.h>
58: #include <netinet/ip_icmp.h>
1.1 cgd 59:
60: #ifndef IPFORWARDING
61: #ifdef GATEWAY
62: #define IPFORWARDING 1 /* forward IP packets not for us */
63: #else /* GATEWAY */
64: #define IPFORWARDING 0 /* don't forward IP packets not for us */
65: #endif /* GATEWAY */
66: #endif /* IPFORWARDING */
67: #ifndef IPSENDREDIRECTS
68: #define IPSENDREDIRECTS 1
69: #endif
70: int ipforwarding = IPFORWARDING;
71: int ipsendredirects = IPSENDREDIRECTS;
1.13 mycroft 72: int ip_defttl = IPDEFTTL;
1.1 cgd 73: #ifdef DIAGNOSTIC
74: int ipprintfs = 0;
75: #endif
76:
77: extern struct domain inetdomain;
78: extern struct protosw inetsw[];
79: u_char ip_protox[IPPROTO_MAX];
80: int ipqmaxlen = IFQ_MAXLEN;
81: struct in_ifaddr *in_ifaddr; /* first inet address */
1.13 mycroft 82: struct ifqueue ipintrq;
1.1 cgd 83:
84: /*
85: * We need to save the IP options in case a protocol wants to respond
86: * to an incoming packet over the same route if the packet got here
87: * using IP source routing. This allows connection establishment and
88: * maintenance when the remote end is on a network that is not known
89: * to us.
90: */
91: int ip_nhops = 0;
92: static struct ip_srcrt {
93: struct in_addr dst; /* final destination */
94: char nop; /* one NOP to align */
95: char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */
96: struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
97: } ip_srcrt;
98:
99: #ifdef GATEWAY
100: extern int if_index;
1.15 cgd 101: u_int32_t *ip_ifmatrix;
1.1 cgd 102: #endif
103:
1.13 mycroft 104: static void save_rte __P((u_char *, struct in_addr));
1.1 cgd 105: /*
106: * IP initialization: fill in IP protocol switch table.
107: * All protocols not implemented in kernel go to raw IP protocol handler.
108: */
1.8 mycroft 109: void
1.1 cgd 110: ip_init()
111: {
112: register struct protosw *pr;
113: register int i;
114:
115: pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
116: if (pr == 0)
117: panic("ip_init");
118: for (i = 0; i < IPPROTO_MAX; i++)
119: ip_protox[i] = pr - inetsw;
120: for (pr = inetdomain.dom_protosw;
121: pr < inetdomain.dom_protoswNPROTOSW; pr++)
122: if (pr->pr_domain->dom_family == PF_INET &&
123: pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
124: ip_protox[pr->pr_protocol] = pr - inetsw;
125: ipq.next = ipq.prev = &ipq;
126: ip_id = time.tv_sec & 0xffff;
127: ipintrq.ifq_maxlen = ipqmaxlen;
128: #ifdef GATEWAY
1.15 cgd 129: i = (if_index + 1) * (if_index + 1) * sizeof (u_int32_t);
130: ip_ifmatrix = (u_int32_t *) malloc(i, M_RTABLE, M_WAITOK);
1.13 mycroft 131: bzero((char *)ip_ifmatrix, i);
1.1 cgd 132: #endif
133: }
134:
135: struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
136: struct route ipforward_rt;
137:
138: /*
139: * Ip input routine. Checksum and byte swap header. If fragmented
140: * try to reassemble. Process options. Pass to next level.
141: */
1.8 mycroft 142: void
1.1 cgd 143: ipintr()
144: {
145: register struct ip *ip;
146: register struct mbuf *m;
147: register struct ipq *fp;
148: register struct in_ifaddr *ia;
149: int hlen, s;
150:
151: next:
152: /*
153: * Get next datagram off input queue and get IP header
154: * in first mbuf.
155: */
156: s = splimp();
157: IF_DEQUEUE(&ipintrq, m);
158: splx(s);
1.13 mycroft 159: if (m == 0)
1.1 cgd 160: return;
161: #ifdef DIAGNOSTIC
162: if ((m->m_flags & M_PKTHDR) == 0)
163: panic("ipintr no HDR");
164: #endif
165: /*
166: * If no IP addresses have been set yet but the interfaces
167: * are receiving, can't do anything with incoming packets yet.
168: */
169: if (in_ifaddr == NULL)
170: goto bad;
171: ipstat.ips_total++;
172: if (m->m_len < sizeof (struct ip) &&
173: (m = m_pullup(m, sizeof (struct ip))) == 0) {
174: ipstat.ips_toosmall++;
175: goto next;
176: }
177: ip = mtod(m, struct ip *);
1.13 mycroft 178: if (ip->ip_v != IPVERSION) {
179: ipstat.ips_badvers++;
180: goto bad;
181: }
1.1 cgd 182: hlen = ip->ip_hl << 2;
183: if (hlen < sizeof(struct ip)) { /* minimum header length */
184: ipstat.ips_badhlen++;
185: goto bad;
186: }
187: if (hlen > m->m_len) {
188: if ((m = m_pullup(m, hlen)) == 0) {
189: ipstat.ips_badhlen++;
190: goto next;
191: }
192: ip = mtod(m, struct ip *);
193: }
194: if (ip->ip_sum = in_cksum(m, hlen)) {
195: ipstat.ips_badsum++;
196: goto bad;
197: }
198:
199: /*
200: * Convert fields to host representation.
201: */
202: NTOHS(ip->ip_len);
203: if (ip->ip_len < hlen) {
204: ipstat.ips_badlen++;
205: goto bad;
206: }
207: NTOHS(ip->ip_id);
208: NTOHS(ip->ip_off);
209:
210: /*
211: * Check that the amount of data in the buffers
212: * is as at least much as the IP header would have us expect.
213: * Trim mbufs if longer than we expect.
214: * Drop packet if shorter than we expect.
215: */
216: if (m->m_pkthdr.len < ip->ip_len) {
217: ipstat.ips_tooshort++;
218: goto bad;
219: }
220: if (m->m_pkthdr.len > ip->ip_len) {
221: if (m->m_len == m->m_pkthdr.len) {
222: m->m_len = ip->ip_len;
223: m->m_pkthdr.len = ip->ip_len;
224: } else
225: m_adj(m, ip->ip_len - m->m_pkthdr.len);
226: }
227:
228: /*
229: * Process options and, if not destined for us,
230: * ship it on. ip_dooptions returns 1 when an
231: * error was detected (causing an icmp message
232: * to be sent and the original packet to be freed).
233: */
234: ip_nhops = 0; /* for source routed packets */
235: if (hlen > sizeof (struct ip) && ip_dooptions(m))
236: goto next;
237:
238: /*
239: * Check our list of addresses, to see if the packet is for us.
240: */
241: for (ia = in_ifaddr; ia; ia = ia->ia_next) {
242: if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
243: goto ours;
244: if (
245: #ifdef DIRECTED_BROADCAST
246: ia->ia_ifp == m->m_pkthdr.rcvif &&
247: #endif
248: (ia->ia_ifp->if_flags & IFF_BROADCAST)) {
1.18 mycroft 249: if (ip->ip_dst.s_addr ==
250: satosin(&ia->ia_broadaddr)->sin_addr.s_addr)
1.1 cgd 251: goto ours;
252: if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr)
253: goto ours;
254: /*
255: * Look for all-0's host part (old broadcast addr),
256: * either for subnet or net.
257: */
1.18 mycroft 258: if (ip->ip_dst.s_addr == ia->ia_subnet ||
259: ip->ip_dst.s_addr == ia->ia_net)
1.1 cgd 260: goto ours;
261: }
262: }
1.18 mycroft 263: if (IN_MULTICAST(ip->ip_dst.s_addr)) {
1.4 hpeyerl 264: struct in_multi *inm;
265: #ifdef MROUTING
266: extern struct socket *ip_mrouter;
1.10 brezak 267:
268: if (m->m_flags & M_EXT) {
269: if ((m = m_pullup(m, hlen)) == 0) {
270: ipstat.ips_toosmall++;
271: goto next;
272: }
273: ip = mtod(m, struct ip *);
274: }
1.4 hpeyerl 275:
276: if (ip_mrouter) {
277: /*
278: * If we are acting as a multicast router, all
279: * incoming multicast packets are passed to the
280: * kernel-level multicast forwarding function.
281: * The packet is returned (relatively) intact; if
282: * ip_mforward() returns a non-zero value, the packet
283: * must be discarded, else it may be accepted below.
284: *
285: * (The IP ident field is put in the same byte order
286: * as expected when ip_mforward() is called from
287: * ip_output().)
288: */
289: ip->ip_id = htons(ip->ip_id);
1.13 mycroft 290: if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) {
291: ipstat.ips_cantforward++;
1.4 hpeyerl 292: m_freem(m);
293: goto next;
294: }
295: ip->ip_id = ntohs(ip->ip_id);
296:
297: /*
298: * The process-level routing demon needs to receive
299: * all multicast IGMP packets, whether or not this
300: * host belongs to their destination groups.
301: */
302: if (ip->ip_p == IPPROTO_IGMP)
303: goto ours;
1.13 mycroft 304: ipstat.ips_forward++;
1.4 hpeyerl 305: }
306: #endif
307: /*
308: * See if we belong to the destination multicast group on the
309: * arrival interface.
310: */
311: IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
312: if (inm == NULL) {
1.13 mycroft 313: ipstat.ips_cantforward++;
1.4 hpeyerl 314: m_freem(m);
315: goto next;
316: }
317: goto ours;
318: }
1.19 ! mycroft 319: if (ip->ip_dst.s_addr == INADDR_BROADCAST ||
! 320: ip->ip_dst.s_addr == INADDR_ANY)
1.1 cgd 321: goto ours;
322:
323: /*
324: * Not for us; forward if possible and desirable.
325: */
326: if (ipforwarding == 0) {
327: ipstat.ips_cantforward++;
328: m_freem(m);
329: } else
330: ip_forward(m, 0);
331: goto next;
332:
333: ours:
334: /*
335: * If offset or IP_MF are set, must reassemble.
336: * Otherwise, nothing need be done.
337: * (We could look in the reassembly queue to see
338: * if the packet was previously fragmented,
339: * but it's not worth the time; just let them time out.)
340: */
341: if (ip->ip_off &~ IP_DF) {
342: if (m->m_flags & M_EXT) { /* XXX */
343: if ((m = m_pullup(m, sizeof (struct ip))) == 0) {
344: ipstat.ips_toosmall++;
345: goto next;
346: }
347: ip = mtod(m, struct ip *);
348: }
349: /*
350: * Look for queue of fragments
351: * of this datagram.
352: */
353: for (fp = ipq.next; fp != &ipq; fp = fp->next)
354: if (ip->ip_id == fp->ipq_id &&
355: ip->ip_src.s_addr == fp->ipq_src.s_addr &&
356: ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
357: ip->ip_p == fp->ipq_p)
358: goto found;
359: fp = 0;
360: found:
361:
362: /*
363: * Adjust ip_len to not reflect header,
364: * set ip_mff if more fragments are expected,
365: * convert offset of this to bytes.
366: */
367: ip->ip_len -= hlen;
1.13 mycroft 368: ((struct ipasfrag *)ip)->ipf_mff &= ~1;
1.16 cgd 369: if (ip->ip_off & IP_MF) {
370: /*
371: * Make sure that fragments have a data length
372: * that's a non-zero multiple of 8 bytes.
373: */
1.17 cgd 374: if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
1.16 cgd 375: ipstat.ips_badfrags++;
376: goto bad;
377: }
1.13 mycroft 378: ((struct ipasfrag *)ip)->ipf_mff |= 1;
1.16 cgd 379: }
1.1 cgd 380: ip->ip_off <<= 3;
381:
382: /*
383: * If datagram marked as having more fragments
384: * or if this is not the first fragment,
385: * attempt reassembly; if it succeeds, proceed.
386: */
1.13 mycroft 387: if (((struct ipasfrag *)ip)->ipf_mff & 1 || ip->ip_off) {
1.1 cgd 388: ipstat.ips_fragments++;
389: ip = ip_reass((struct ipasfrag *)ip, fp);
390: if (ip == 0)
391: goto next;
1.13 mycroft 392: ipstat.ips_reassembled++;
1.1 cgd 393: m = dtom(ip);
394: } else
395: if (fp)
396: ip_freef(fp);
397: } else
398: ip->ip_len -= hlen;
399:
400: /*
401: * Switch out to protocol's input routine.
402: */
403: ipstat.ips_delivered++;
404: (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
405: goto next;
406: bad:
407: m_freem(m);
408: goto next;
409: }
410:
411: /*
412: * Take incoming datagram fragment and try to
413: * reassemble it into whole datagram. If a chain for
414: * reassembly of this datagram already exists, then it
415: * is given as fp; otherwise have to make a chain.
416: */
417: struct ip *
418: ip_reass(ip, fp)
419: register struct ipasfrag *ip;
420: register struct ipq *fp;
421: {
422: register struct mbuf *m = dtom(ip);
423: register struct ipasfrag *q;
424: struct mbuf *t;
425: int hlen = ip->ip_hl << 2;
426: int i, next;
427:
428: /*
429: * Presence of header sizes in mbufs
430: * would confuse code below.
431: */
432: m->m_data += hlen;
433: m->m_len -= hlen;
434:
435: /*
436: * If first fragment to arrive, create a reassembly queue.
437: */
438: if (fp == 0) {
439: if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
440: goto dropfrag;
441: fp = mtod(t, struct ipq *);
442: insque(fp, &ipq);
443: fp->ipq_ttl = IPFRAGTTL;
444: fp->ipq_p = ip->ip_p;
445: fp->ipq_id = ip->ip_id;
446: fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp;
447: fp->ipq_src = ((struct ip *)ip)->ip_src;
448: fp->ipq_dst = ((struct ip *)ip)->ip_dst;
449: q = (struct ipasfrag *)fp;
450: goto insert;
451: }
452:
453: /*
454: * Find a segment which begins after this one does.
455: */
456: for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next)
457: if (q->ip_off > ip->ip_off)
458: break;
459:
460: /*
461: * If there is a preceding segment, it may provide some of
462: * our data already. If so, drop the data from the incoming
463: * segment. If it provides all of our data, drop us.
464: */
465: if (q->ipf_prev != (struct ipasfrag *)fp) {
466: i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off;
467: if (i > 0) {
468: if (i >= ip->ip_len)
469: goto dropfrag;
470: m_adj(dtom(ip), i);
471: ip->ip_off += i;
472: ip->ip_len -= i;
473: }
474: }
475:
476: /*
477: * While we overlap succeeding segments trim them or,
478: * if they are completely covered, dequeue them.
479: */
480: while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) {
481: i = (ip->ip_off + ip->ip_len) - q->ip_off;
482: if (i < q->ip_len) {
483: q->ip_len -= i;
484: q->ip_off += i;
485: m_adj(dtom(q), i);
486: break;
487: }
488: q = q->ipf_next;
489: m_freem(dtom(q->ipf_prev));
490: ip_deq(q->ipf_prev);
491: }
492:
493: insert:
494: /*
495: * Stick new segment in its place;
496: * check for complete reassembly.
497: */
498: ip_enq(ip, q->ipf_prev);
499: next = 0;
500: for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) {
501: if (q->ip_off != next)
502: return (0);
503: next += q->ip_len;
504: }
1.13 mycroft 505: if (q->ipf_prev->ipf_mff & 1)
1.1 cgd 506: return (0);
507:
508: /*
509: * Reassembly is complete; concatenate fragments.
510: */
511: q = fp->ipq_next;
512: m = dtom(q);
513: t = m->m_next;
514: m->m_next = 0;
515: m_cat(m, t);
516: q = q->ipf_next;
517: while (q != (struct ipasfrag *)fp) {
518: t = dtom(q);
519: q = q->ipf_next;
520: m_cat(m, t);
521: }
522:
523: /*
524: * Create header for new ip packet by
525: * modifying header of first packet;
526: * dequeue and discard fragment reassembly header.
527: * Make header visible.
528: */
529: ip = fp->ipq_next;
530: ip->ip_len = next;
1.13 mycroft 531: ip->ipf_mff &= ~1;
1.1 cgd 532: ((struct ip *)ip)->ip_src = fp->ipq_src;
533: ((struct ip *)ip)->ip_dst = fp->ipq_dst;
534: remque(fp);
535: (void) m_free(dtom(fp));
536: m = dtom(ip);
537: m->m_len += (ip->ip_hl << 2);
538: m->m_data -= (ip->ip_hl << 2);
539: /* some debugging cruft by sklower, below, will go away soon */
540: if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
541: register int plen = 0;
542: for (t = m; m; m = m->m_next)
543: plen += m->m_len;
544: t->m_pkthdr.len = plen;
545: }
546: return ((struct ip *)ip);
547:
548: dropfrag:
549: ipstat.ips_fragdropped++;
550: m_freem(m);
551: return (0);
552: }
553:
554: /*
555: * Free a fragment reassembly header and all
556: * associated datagrams.
557: */
1.8 mycroft 558: void
1.1 cgd 559: ip_freef(fp)
560: struct ipq *fp;
561: {
562: register struct ipasfrag *q, *p;
563:
564: for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) {
565: p = q->ipf_next;
566: ip_deq(q);
567: m_freem(dtom(q));
568: }
569: remque(fp);
570: (void) m_free(dtom(fp));
571: }
572:
573: /*
574: * Put an ip fragment on a reassembly chain.
575: * Like insque, but pointers in middle of structure.
576: */
1.8 mycroft 577: void
1.1 cgd 578: ip_enq(p, prev)
579: register struct ipasfrag *p, *prev;
580: {
581:
582: p->ipf_prev = prev;
583: p->ipf_next = prev->ipf_next;
584: prev->ipf_next->ipf_prev = p;
585: prev->ipf_next = p;
586: }
587:
588: /*
589: * To ip_enq as remque is to insque.
590: */
1.8 mycroft 591: void
1.1 cgd 592: ip_deq(p)
593: register struct ipasfrag *p;
594: {
595:
596: p->ipf_prev->ipf_next = p->ipf_next;
597: p->ipf_next->ipf_prev = p->ipf_prev;
598: }
599:
600: /*
601: * IP timer processing;
602: * if a timer expires on a reassembly
603: * queue, discard it.
604: */
1.8 mycroft 605: void
1.1 cgd 606: ip_slowtimo()
607: {
608: register struct ipq *fp;
609: int s = splnet();
610:
611: fp = ipq.next;
612: if (fp == 0) {
613: splx(s);
614: return;
615: }
616: while (fp != &ipq) {
617: --fp->ipq_ttl;
618: fp = fp->next;
619: if (fp->prev->ipq_ttl == 0) {
620: ipstat.ips_fragtimeout++;
621: ip_freef(fp->prev);
622: }
623: }
624: splx(s);
625: }
626:
627: /*
628: * Drain off all datagram fragments.
629: */
1.8 mycroft 630: void
1.1 cgd 631: ip_drain()
632: {
633:
634: while (ipq.next != &ipq) {
635: ipstat.ips_fragdropped++;
636: ip_freef(ipq.next);
637: }
638: }
639:
640: /*
641: * Do option processing on a datagram,
642: * possibly discarding it if bad options are encountered,
643: * or forwarding it if source-routed.
644: * Returns 1 if packet has been forwarded/freed,
645: * 0 if the packet should be processed further.
646: */
1.8 mycroft 647: int
1.1 cgd 648: ip_dooptions(m)
649: struct mbuf *m;
650: {
651: register struct ip *ip = mtod(m, struct ip *);
652: register u_char *cp;
653: register struct ip_timestamp *ipt;
654: register struct in_ifaddr *ia;
655: int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
1.13 mycroft 656: struct in_addr *sin, dst;
1.1 cgd 657: n_time ntime;
658:
1.13 mycroft 659: dst = ip->ip_dst;
1.1 cgd 660: cp = (u_char *)(ip + 1);
661: cnt = (ip->ip_hl << 2) - sizeof (struct ip);
662: for (; cnt > 0; cnt -= optlen, cp += optlen) {
663: opt = cp[IPOPT_OPTVAL];
664: if (opt == IPOPT_EOL)
665: break;
666: if (opt == IPOPT_NOP)
667: optlen = 1;
668: else {
669: optlen = cp[IPOPT_OLEN];
670: if (optlen <= 0 || optlen > cnt) {
671: code = &cp[IPOPT_OLEN] - (u_char *)ip;
672: goto bad;
673: }
674: }
675: switch (opt) {
676:
677: default:
678: break;
679:
680: /*
681: * Source routing with record.
682: * Find interface with current destination address.
683: * If none on this machine then drop if strictly routed,
684: * or do nothing if loosely routed.
685: * Record interface address and bring up next address
686: * component. If strictly routed make sure next
687: * address is on directly accessible net.
688: */
689: case IPOPT_LSRR:
690: case IPOPT_SSRR:
691: if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
692: code = &cp[IPOPT_OFFSET] - (u_char *)ip;
693: goto bad;
694: }
695: ipaddr.sin_addr = ip->ip_dst;
1.19 ! mycroft 696: ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)));
1.1 cgd 697: if (ia == 0) {
698: if (opt == IPOPT_SSRR) {
699: type = ICMP_UNREACH;
700: code = ICMP_UNREACH_SRCFAIL;
701: goto bad;
702: }
703: /*
704: * Loose routing, and not at next destination
705: * yet; nothing to do except forward.
706: */
707: break;
708: }
709: off--; /* 0 origin */
710: if (off > optlen - sizeof(struct in_addr)) {
711: /*
712: * End of source route. Should be for us.
713: */
714: save_rte(cp, ip->ip_src);
715: break;
716: }
717: /*
718: * locate outgoing interface
719: */
720: bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
721: sizeof(ipaddr.sin_addr));
722: if (opt == IPOPT_SSRR) {
723: #define INA struct in_ifaddr *
724: #define SA struct sockaddr *
725: if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
1.13 mycroft 726: ia = (INA)ifa_ifwithnet((SA)&ipaddr);
1.1 cgd 727: } else
728: ia = ip_rtaddr(ipaddr.sin_addr);
729: if (ia == 0) {
730: type = ICMP_UNREACH;
731: code = ICMP_UNREACH_SRCFAIL;
732: goto bad;
733: }
734: ip->ip_dst = ipaddr.sin_addr;
735: bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
736: (caddr_t)(cp + off), sizeof(struct in_addr));
737: cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1.13 mycroft 738: /*
739: * Let ip_intr's mcast routing check handle mcast pkts
740: */
1.18 mycroft 741: forward = !IN_MULTICAST(ip->ip_dst.s_addr);
1.1 cgd 742: break;
743:
744: case IPOPT_RR:
745: if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
746: code = &cp[IPOPT_OFFSET] - (u_char *)ip;
747: goto bad;
748: }
749: /*
750: * If no space remains, ignore.
751: */
752: off--; /* 0 origin */
753: if (off > optlen - sizeof(struct in_addr))
754: break;
755: bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
756: sizeof(ipaddr.sin_addr));
757: /*
758: * locate outgoing interface; if we're the destination,
759: * use the incoming interface (should be same).
760: */
761: if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
762: (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
763: type = ICMP_UNREACH;
764: code = ICMP_UNREACH_HOST;
765: goto bad;
766: }
767: bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
768: (caddr_t)(cp + off), sizeof(struct in_addr));
769: cp[IPOPT_OFFSET] += sizeof(struct in_addr);
770: break;
771:
772: case IPOPT_TS:
773: code = cp - (u_char *)ip;
774: ipt = (struct ip_timestamp *)cp;
775: if (ipt->ipt_len < 5)
776: goto bad;
1.15 cgd 777: if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
1.1 cgd 778: if (++ipt->ipt_oflw == 0)
779: goto bad;
780: break;
781: }
782: sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
783: switch (ipt->ipt_flg) {
784:
785: case IPOPT_TS_TSONLY:
786: break;
787:
788: case IPOPT_TS_TSANDADDR:
789: if (ipt->ipt_ptr + sizeof(n_time) +
790: sizeof(struct in_addr) > ipt->ipt_len)
791: goto bad;
1.13 mycroft 792: ipaddr.sin_addr = dst;
793: ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
794: m->m_pkthdr.rcvif);
795: if (ia == 0)
796: continue;
1.1 cgd 797: bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
798: (caddr_t)sin, sizeof(struct in_addr));
799: ipt->ipt_ptr += sizeof(struct in_addr);
800: break;
801:
802: case IPOPT_TS_PRESPEC:
803: if (ipt->ipt_ptr + sizeof(n_time) +
804: sizeof(struct in_addr) > ipt->ipt_len)
805: goto bad;
806: bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
807: sizeof(struct in_addr));
808: if (ifa_ifwithaddr((SA)&ipaddr) == 0)
809: continue;
810: ipt->ipt_ptr += sizeof(struct in_addr);
811: break;
812:
813: default:
814: goto bad;
815: }
816: ntime = iptime();
817: bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
818: sizeof(n_time));
819: ipt->ipt_ptr += sizeof(n_time);
820: }
821: }
822: if (forward) {
823: ip_forward(m, 1);
824: return (1);
1.13 mycroft 825: }
826: return (0);
1.1 cgd 827: bad:
1.13 mycroft 828: ip->ip_len -= ip->ip_hl << 2; /* XXX icmp_error adds in hdr length */
829: icmp_error(m, type, code, 0, 0);
830: ipstat.ips_badoptions++;
1.1 cgd 831: return (1);
832: }
833:
834: /*
835: * Given address of next destination (final or next hop),
836: * return internet address info of interface to be used to get there.
837: */
838: struct in_ifaddr *
839: ip_rtaddr(dst)
840: struct in_addr dst;
841: {
842: register struct sockaddr_in *sin;
843:
1.19 ! mycroft 844: sin = satosin(&ipforward_rt.ro_dst);
1.1 cgd 845:
846: if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) {
847: if (ipforward_rt.ro_rt) {
848: RTFREE(ipforward_rt.ro_rt);
849: ipforward_rt.ro_rt = 0;
850: }
851: sin->sin_family = AF_INET;
852: sin->sin_len = sizeof(*sin);
853: sin->sin_addr = dst;
854:
855: rtalloc(&ipforward_rt);
856: }
857: if (ipforward_rt.ro_rt == 0)
858: return ((struct in_ifaddr *)0);
1.19 ! mycroft 859: return (ifatoia(ipforward_rt.ro_rt->rt_ifa));
1.1 cgd 860: }
861:
862: /*
863: * Save incoming source route for use in replies,
864: * to be picked up later by ip_srcroute if the receiver is interested.
865: */
1.13 mycroft 866: void
1.1 cgd 867: save_rte(option, dst)
868: u_char *option;
869: struct in_addr dst;
870: {
871: unsigned olen;
872:
873: olen = option[IPOPT_OLEN];
874: #ifdef DIAGNOSTIC
875: if (ipprintfs)
876: printf("save_rte: olen %d\n", olen);
877: #endif
878: if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
879: return;
880: bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen);
881: ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
882: ip_srcrt.dst = dst;
883: }
884:
885: /*
886: * Retrieve incoming source route for use in replies,
887: * in the same form used by setsockopt.
888: * The first hop is placed before the options, will be removed later.
889: */
890: struct mbuf *
891: ip_srcroute()
892: {
893: register struct in_addr *p, *q;
894: register struct mbuf *m;
895:
896: if (ip_nhops == 0)
897: return ((struct mbuf *)0);
898: m = m_get(M_DONTWAIT, MT_SOOPTS);
899: if (m == 0)
900: return ((struct mbuf *)0);
901:
1.13 mycroft 902: #define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
1.1 cgd 903:
904: /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
905: m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
906: OPTSIZ;
907: #ifdef DIAGNOSTIC
908: if (ipprintfs)
909: printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
910: #endif
911:
912: /*
913: * First save first hop for return route
914: */
915: p = &ip_srcrt.route[ip_nhops - 1];
916: *(mtod(m, struct in_addr *)) = *p--;
917: #ifdef DIAGNOSTIC
918: if (ipprintfs)
919: printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr));
920: #endif
921:
922: /*
923: * Copy option fields and padding (nop) to mbuf.
924: */
925: ip_srcrt.nop = IPOPT_NOP;
926: ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
927: bcopy((caddr_t)&ip_srcrt.nop,
928: mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ);
929: q = (struct in_addr *)(mtod(m, caddr_t) +
930: sizeof(struct in_addr) + OPTSIZ);
931: #undef OPTSIZ
932: /*
933: * Record return path as an IP source route,
934: * reversing the path (pointers are now aligned).
935: */
936: while (p >= ip_srcrt.route) {
937: #ifdef DIAGNOSTIC
938: if (ipprintfs)
939: printf(" %lx", ntohl(q->s_addr));
940: #endif
941: *q++ = *p--;
942: }
943: /*
944: * Last hop goes to final destination.
945: */
946: *q = ip_srcrt.dst;
947: #ifdef DIAGNOSTIC
948: if (ipprintfs)
949: printf(" %lx\n", ntohl(q->s_addr));
950: #endif
951: return (m);
952: }
953:
954: /*
955: * Strip out IP options, at higher
956: * level protocol in the kernel.
957: * Second argument is buffer to which options
958: * will be moved, and return value is their length.
959: * XXX should be deleted; last arg currently ignored.
960: */
1.8 mycroft 961: void
1.1 cgd 962: ip_stripoptions(m, mopt)
963: register struct mbuf *m;
964: struct mbuf *mopt;
965: {
966: register int i;
967: struct ip *ip = mtod(m, struct ip *);
968: register caddr_t opts;
969: int olen;
970:
971: olen = (ip->ip_hl<<2) - sizeof (struct ip);
972: opts = (caddr_t)(ip + 1);
973: i = m->m_len - (sizeof (struct ip) + olen);
974: bcopy(opts + olen, opts, (unsigned)i);
975: m->m_len -= olen;
976: if (m->m_flags & M_PKTHDR)
977: m->m_pkthdr.len -= olen;
978: ip->ip_hl = sizeof(struct ip) >> 2;
979: }
980:
981: u_char inetctlerrmap[PRC_NCMDS] = {
982: 0, 0, 0, 0,
983: 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH,
984: EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED,
985: EMSGSIZE, EHOSTUNREACH, 0, 0,
986: 0, 0, 0, 0,
987: ENOPROTOOPT
988: };
989:
990: /*
991: * Forward a packet. If some error occurs return the sender
992: * an icmp packet. Note we can't always generate a meaningful
993: * icmp message because icmp doesn't have a large enough repertoire
994: * of codes and types.
995: *
996: * If not forwarding, just drop the packet. This could be confusing
997: * if ipforwarding was zero but some routing protocol was advancing
998: * us as a gateway to somewhere. However, we must let the routing
999: * protocol deal with that.
1000: *
1001: * The srcrt parameter indicates whether the packet is being forwarded
1002: * via a source route.
1003: */
1.13 mycroft 1004: void
1.1 cgd 1005: ip_forward(m, srcrt)
1006: struct mbuf *m;
1007: int srcrt;
1008: {
1009: register struct ip *ip = mtod(m, struct ip *);
1010: register struct sockaddr_in *sin;
1011: register struct rtentry *rt;
1012: int error, type = 0, code;
1013: struct mbuf *mcopy;
1.13 mycroft 1014: n_long dest;
1015: struct ifnet *destifp;
1.1 cgd 1016:
1.13 mycroft 1017: dest = 0;
1.1 cgd 1018: #ifdef DIAGNOSTIC
1019: if (ipprintfs)
1020: printf("forward: src %x dst %x ttl %x\n", ip->ip_src,
1021: ip->ip_dst, ip->ip_ttl);
1022: #endif
1023: if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) {
1024: ipstat.ips_cantforward++;
1025: m_freem(m);
1026: return;
1027: }
1028: HTONS(ip->ip_id);
1029: if (ip->ip_ttl <= IPTTLDEC) {
1.13 mycroft 1030: icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
1.1 cgd 1031: return;
1032: }
1033: ip->ip_ttl -= IPTTLDEC;
1034:
1.19 ! mycroft 1035: sin = satosin(&ipforward_rt.ro_dst);
1.1 cgd 1036: if ((rt = ipforward_rt.ro_rt) == 0 ||
1037: ip->ip_dst.s_addr != sin->sin_addr.s_addr) {
1038: if (ipforward_rt.ro_rt) {
1039: RTFREE(ipforward_rt.ro_rt);
1040: ipforward_rt.ro_rt = 0;
1041: }
1042: sin->sin_family = AF_INET;
1043: sin->sin_len = sizeof(*sin);
1044: sin->sin_addr = ip->ip_dst;
1045:
1046: rtalloc(&ipforward_rt);
1047: if (ipforward_rt.ro_rt == 0) {
1.13 mycroft 1048: icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
1.1 cgd 1049: return;
1050: }
1051: rt = ipforward_rt.ro_rt;
1052: }
1053:
1054: /*
1055: * Save at most 64 bytes of the packet in case
1056: * we need to generate an ICMP message to the src.
1057: */
1058: mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64));
1059:
1060: #ifdef GATEWAY
1061: ip_ifmatrix[rt->rt_ifp->if_index +
1062: if_index * m->m_pkthdr.rcvif->if_index]++;
1063: #endif
1064: /*
1065: * If forwarding packet using same interface that it came in on,
1066: * perhaps should send a redirect to sender to shortcut a hop.
1067: * Only send redirect if source is sending directly to us,
1068: * and if packet was not source routed (or has any options).
1069: * Also, don't send redirect if forwarding using a default route
1070: * or a route modified by a redirect.
1071: */
1072: if (rt->rt_ifp == m->m_pkthdr.rcvif &&
1073: (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1074: satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
1075: ipsendredirects && !srcrt) {
1.19 ! mycroft 1076: if (rt->rt_ifa &&
! 1077: (ip->ip_src.s_addr & ifatoia(rt->rt_ifa)->ia_subnetmask) ==
! 1078: ifatoia(rt->rt_ifa)->ia_subnet) {
1.1 cgd 1079: if (rt->rt_flags & RTF_GATEWAY)
1.13 mycroft 1080: dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
1.1 cgd 1081: else
1.13 mycroft 1082: dest = ip->ip_dst.s_addr;
1083: /* Router requirements says to only send host redirects */
1.1 cgd 1084: type = ICMP_REDIRECT;
1.13 mycroft 1085: code = ICMP_REDIRECT_HOST;
1.1 cgd 1086: #ifdef DIAGNOSTIC
1087: if (ipprintfs)
1.15 cgd 1088: printf("redirect (%d) to %lx\n", code, (u_int32_t)dest);
1.1 cgd 1089: #endif
1090: }
1091: }
1092:
1.13 mycroft 1093: error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING
1.9 mycroft 1094: #ifdef DIRECTED_BROADCAST
1.13 mycroft 1095: | IP_ALLOWBROADCAST
1.9 mycroft 1096: #endif
1.13 mycroft 1097: , 0);
1.1 cgd 1098: if (error)
1099: ipstat.ips_cantforward++;
1100: else {
1101: ipstat.ips_forward++;
1102: if (type)
1103: ipstat.ips_redirectsent++;
1104: else {
1105: if (mcopy)
1106: m_freem(mcopy);
1107: return;
1108: }
1109: }
1110: if (mcopy == NULL)
1111: return;
1.13 mycroft 1112: destifp = NULL;
1113:
1.1 cgd 1114: switch (error) {
1115:
1116: case 0: /* forwarded, but need redirect */
1117: /* type, code set above */
1118: break;
1119:
1120: case ENETUNREACH: /* shouldn't happen, checked above */
1121: case EHOSTUNREACH:
1122: case ENETDOWN:
1123: case EHOSTDOWN:
1124: default:
1125: type = ICMP_UNREACH;
1126: code = ICMP_UNREACH_HOST;
1127: break;
1128:
1129: case EMSGSIZE:
1130: type = ICMP_UNREACH;
1131: code = ICMP_UNREACH_NEEDFRAG;
1.13 mycroft 1132: if (ipforward_rt.ro_rt)
1133: destifp = ipforward_rt.ro_rt->rt_ifp;
1.1 cgd 1134: ipstat.ips_cantfrag++;
1135: break;
1136:
1137: case ENOBUFS:
1138: type = ICMP_SOURCEQUENCH;
1139: code = 0;
1140: break;
1141: }
1.13 mycroft 1142: icmp_error(mcopy, type, code, dest, destifp);
1143: }
1144:
1145: int
1146: ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
1147: int *name;
1148: u_int namelen;
1149: void *oldp;
1150: size_t *oldlenp;
1151: void *newp;
1152: size_t newlen;
1153: {
1154: /* All sysctl names at this level are terminal. */
1155: if (namelen != 1)
1156: return (ENOTDIR);
1157:
1158: switch (name[0]) {
1159: case IPCTL_FORWARDING:
1160: return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding));
1161: case IPCTL_SENDREDIRECTS:
1162: return (sysctl_int(oldp, oldlenp, newp, newlen,
1163: &ipsendredirects));
1164: case IPCTL_DEFTTL:
1165: return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl));
1166: #ifdef notyet
1167: case IPCTL_DEFMTU:
1168: return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu));
1169: #endif
1170: default:
1171: return (EOPNOTSUPP);
1172: }
1173: /* NOTREACHED */
1.1 cgd 1174: }
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