Annotation of src/sys/netinet/ip_input.c, Revision 1.12
1.1 cgd 1: /*
2: * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
3: * All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: * 3. All advertising materials mentioning features or use of this software
14: * must display the following acknowledgement:
15: * This product includes software developed by the University of
16: * California, Berkeley and its contributors.
17: * 4. Neither the name of the University nor the names of its contributors
18: * may be used to endorse or promote products derived from this software
19: * without specific prior written permission.
20: *
21: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31: * SUCH DAMAGE.
32: *
1.3 cgd 33: * from: @(#)ip_input.c 7.19 (Berkeley) 5/25/91
1.12 ! mycroft 34: * $Id: ip_input.c,v 1.11 1994/02/02 05:59:04 hpeyerl Exp $
1.1 cgd 35: */
36:
1.5 mycroft 37: #include <sys/param.h>
38: #include <sys/systm.h>
39: #include <sys/malloc.h>
40: #include <sys/mbuf.h>
41: #include <sys/domain.h>
42: #include <sys/protosw.h>
43: #include <sys/socket.h>
44: #include <sys/errno.h>
45: #include <sys/time.h>
46: #include <sys/kernel.h>
1.1 cgd 47:
1.5 mycroft 48: #include <net/if.h>
49: #include <net/route.h>
1.1 cgd 50:
1.5 mycroft 51: #include <netinet/in.h>
52: #include <netinet/in_systm.h>
53: #include <netinet/ip.h>
54: #include <netinet/in_pcb.h>
55: #include <netinet/in_var.h>
56: #include <netinet/ip_var.h>
57: #include <netinet/ip_icmp.h>
1.8 mycroft 58: #include <netinet/ip_mroute.h>
1.1 cgd 59:
60: #ifndef IPFORWARDING
61: #ifdef GATEWAY
62: #define IPFORWARDING 1 /* forward IP packets not for us */
63: #else /* GATEWAY */
64: #define IPFORWARDING 0 /* don't forward IP packets not for us */
65: #endif /* GATEWAY */
66: #endif /* IPFORWARDING */
67: #ifndef IPSENDREDIRECTS
68: #define IPSENDREDIRECTS 1
69: #endif
70: int ipforwarding = IPFORWARDING;
71: int ipsendredirects = IPSENDREDIRECTS;
72: #ifdef DIAGNOSTIC
73: int ipprintfs = 0;
74: #endif
75:
76: extern struct domain inetdomain;
77: extern struct protosw inetsw[];
78: u_char ip_protox[IPPROTO_MAX];
79: int ipqmaxlen = IFQ_MAXLEN;
80: struct in_ifaddr *in_ifaddr; /* first inet address */
81:
82: /*
83: * We need to save the IP options in case a protocol wants to respond
84: * to an incoming packet over the same route if the packet got here
85: * using IP source routing. This allows connection establishment and
86: * maintenance when the remote end is on a network that is not known
87: * to us.
88: */
89: int ip_nhops = 0;
90: static struct ip_srcrt {
91: struct in_addr dst; /* final destination */
92: char nop; /* one NOP to align */
93: char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */
94: struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
95: } ip_srcrt;
96:
97: #ifdef GATEWAY
98: extern int if_index;
99: u_long *ip_ifmatrix;
100: #endif
101:
1.8 mycroft 102: static void ip_forward __P((struct mbuf *, int));
103: static void save_rte __P((u_char *, struct in_addr));
104:
1.1 cgd 105: /*
106: * IP initialization: fill in IP protocol switch table.
107: * All protocols not implemented in kernel go to raw IP protocol handler.
108: */
1.8 mycroft 109: void
1.1 cgd 110: ip_init()
111: {
112: register struct protosw *pr;
113: register int i;
114:
115: pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
116: if (pr == 0)
117: panic("ip_init");
118: for (i = 0; i < IPPROTO_MAX; i++)
119: ip_protox[i] = pr - inetsw;
120: for (pr = inetdomain.dom_protosw;
121: pr < inetdomain.dom_protoswNPROTOSW; pr++)
122: if (pr->pr_domain->dom_family == PF_INET &&
123: pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
124: ip_protox[pr->pr_protocol] = pr - inetsw;
125: ipq.next = ipq.prev = &ipq;
126: ip_id = time.tv_sec & 0xffff;
127: ipintrq.ifq_maxlen = ipqmaxlen;
128: #ifdef GATEWAY
129: i = (if_index + 1) * (if_index + 1) * sizeof (u_long);
130: if ((ip_ifmatrix = (u_long *) malloc(i, M_RTABLE, M_WAITOK)) == 0)
131: panic("no memory for ip_ifmatrix");
132: #endif
133: }
134:
135: struct ip *ip_reass();
136: struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
137: struct route ipforward_rt;
138:
139: /*
140: * Ip input routine. Checksum and byte swap header. If fragmented
141: * try to reassemble. Process options. Pass to next level.
142: */
1.8 mycroft 143: void
1.1 cgd 144: ipintr()
145: {
146: register struct ip *ip;
147: register struct mbuf *m;
148: register struct ipq *fp;
149: register struct in_ifaddr *ia;
150: int hlen, s;
1.12 ! mycroft 151: #ifdef DIAGNOSTIC
1.2 cgd 152: static int busy = 0;
1.1 cgd 153:
1.2 cgd 154: if (busy)
155: panic("ipintr: called recursively\n");
156: ++busy;
157: #endif
1.1 cgd 158: next:
159: /*
160: * Get next datagram off input queue and get IP header
161: * in first mbuf.
162: */
163: s = splimp();
164: IF_DEQUEUE(&ipintrq, m);
165: splx(s);
1.2 cgd 166: if (m == 0) {
1.12 ! mycroft 167: #ifdef DIAGNOSTIC
1.2 cgd 168: --busy;
169: #endif
1.1 cgd 170: return;
1.2 cgd 171: }
1.1 cgd 172: #ifdef DIAGNOSTIC
173: if ((m->m_flags & M_PKTHDR) == 0)
174: panic("ipintr no HDR");
175: #endif
176: /*
177: * If no IP addresses have been set yet but the interfaces
178: * are receiving, can't do anything with incoming packets yet.
179: */
180: if (in_ifaddr == NULL)
181: goto bad;
182: ipstat.ips_total++;
183: if (m->m_len < sizeof (struct ip) &&
184: (m = m_pullup(m, sizeof (struct ip))) == 0) {
185: ipstat.ips_toosmall++;
186: goto next;
187: }
188: ip = mtod(m, struct ip *);
189: hlen = ip->ip_hl << 2;
190: if (hlen < sizeof(struct ip)) { /* minimum header length */
191: ipstat.ips_badhlen++;
192: goto bad;
193: }
194: if (hlen > m->m_len) {
195: if ((m = m_pullup(m, hlen)) == 0) {
196: ipstat.ips_badhlen++;
197: goto next;
198: }
199: ip = mtod(m, struct ip *);
200: }
201: if (ip->ip_sum = in_cksum(m, hlen)) {
202: ipstat.ips_badsum++;
203: goto bad;
204: }
205:
206: /*
207: * Convert fields to host representation.
208: */
209: NTOHS(ip->ip_len);
210: if (ip->ip_len < hlen) {
211: ipstat.ips_badlen++;
212: goto bad;
213: }
214: NTOHS(ip->ip_id);
215: NTOHS(ip->ip_off);
216:
217: /*
218: * Check that the amount of data in the buffers
219: * is as at least much as the IP header would have us expect.
220: * Trim mbufs if longer than we expect.
221: * Drop packet if shorter than we expect.
222: */
223: if (m->m_pkthdr.len < ip->ip_len) {
224: ipstat.ips_tooshort++;
225: goto bad;
226: }
227: if (m->m_pkthdr.len > ip->ip_len) {
228: if (m->m_len == m->m_pkthdr.len) {
229: m->m_len = ip->ip_len;
230: m->m_pkthdr.len = ip->ip_len;
231: } else
232: m_adj(m, ip->ip_len - m->m_pkthdr.len);
233: }
234:
235: /*
236: * Process options and, if not destined for us,
237: * ship it on. ip_dooptions returns 1 when an
238: * error was detected (causing an icmp message
239: * to be sent and the original packet to be freed).
240: */
241: ip_nhops = 0; /* for source routed packets */
242: if (hlen > sizeof (struct ip) && ip_dooptions(m))
243: goto next;
244:
245: /*
246: * Check our list of addresses, to see if the packet is for us.
247: */
248: for (ia = in_ifaddr; ia; ia = ia->ia_next) {
249: #define satosin(sa) ((struct sockaddr_in *)(sa))
250:
251: if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
252: goto ours;
253: if (
254: #ifdef DIRECTED_BROADCAST
255: ia->ia_ifp == m->m_pkthdr.rcvif &&
256: #endif
257: (ia->ia_ifp->if_flags & IFF_BROADCAST)) {
258: u_long t;
259:
260: if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
261: ip->ip_dst.s_addr)
262: goto ours;
263: if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr)
264: goto ours;
265: /*
266: * Look for all-0's host part (old broadcast addr),
267: * either for subnet or net.
268: */
269: t = ntohl(ip->ip_dst.s_addr);
270: if (t == ia->ia_subnet)
271: goto ours;
272: if (t == ia->ia_net)
273: goto ours;
274: }
275: }
1.4 hpeyerl 276: if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
277: struct in_multi *inm;
278: #ifdef MROUTING
279: extern struct socket *ip_mrouter;
1.10 brezak 280:
281: if (m->m_flags & M_EXT) {
282: if ((m = m_pullup(m, hlen)) == 0) {
283: ipstat.ips_toosmall++;
284: goto next;
285: }
286: ip = mtod(m, struct ip *);
287: }
1.4 hpeyerl 288:
289: if (ip_mrouter) {
290: /*
291: * If we are acting as a multicast router, all
292: * incoming multicast packets are passed to the
293: * kernel-level multicast forwarding function.
294: * The packet is returned (relatively) intact; if
295: * ip_mforward() returns a non-zero value, the packet
296: * must be discarded, else it may be accepted below.
297: *
298: * (The IP ident field is put in the same byte order
299: * as expected when ip_mforward() is called from
300: * ip_output().)
301: */
302: ip->ip_id = htons(ip->ip_id);
303: if (ip_mforward(ip, m->m_pkthdr.rcvif, m) != 0) {
304: m_freem(m);
305: goto next;
306: }
307: ip->ip_id = ntohs(ip->ip_id);
308:
309: /*
310: * The process-level routing demon needs to receive
311: * all multicast IGMP packets, whether or not this
312: * host belongs to their destination groups.
313: */
314: if (ip->ip_p == IPPROTO_IGMP)
315: goto ours;
316: }
317: #endif
318: /*
319: * See if we belong to the destination multicast group on the
320: * arrival interface.
321: */
322: IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
323: if (inm == NULL) {
324: m_freem(m);
325: goto next;
326: }
327: goto ours;
328: }
1.1 cgd 329: if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
330: goto ours;
331: if (ip->ip_dst.s_addr == INADDR_ANY)
332: goto ours;
333:
334: /*
335: * Not for us; forward if possible and desirable.
336: */
337: if (ipforwarding == 0) {
338: ipstat.ips_cantforward++;
339: m_freem(m);
340: } else
341: ip_forward(m, 0);
342: goto next;
343:
344: ours:
345: /*
346: * If offset or IP_MF are set, must reassemble.
347: * Otherwise, nothing need be done.
348: * (We could look in the reassembly queue to see
349: * if the packet was previously fragmented,
350: * but it's not worth the time; just let them time out.)
351: */
352: if (ip->ip_off &~ IP_DF) {
353: if (m->m_flags & M_EXT) { /* XXX */
354: if ((m = m_pullup(m, sizeof (struct ip))) == 0) {
355: ipstat.ips_toosmall++;
356: goto next;
357: }
358: ip = mtod(m, struct ip *);
359: }
360: /*
361: * Look for queue of fragments
362: * of this datagram.
363: */
364: for (fp = ipq.next; fp != &ipq; fp = fp->next)
365: if (ip->ip_id == fp->ipq_id &&
366: ip->ip_src.s_addr == fp->ipq_src.s_addr &&
367: ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
368: ip->ip_p == fp->ipq_p)
369: goto found;
370: fp = 0;
371: found:
372:
373: /*
374: * Adjust ip_len to not reflect header,
375: * set ip_mff if more fragments are expected,
376: * convert offset of this to bytes.
377: */
378: ip->ip_len -= hlen;
379: ((struct ipasfrag *)ip)->ipf_mff = 0;
380: if (ip->ip_off & IP_MF)
381: ((struct ipasfrag *)ip)->ipf_mff = 1;
382: ip->ip_off <<= 3;
383:
384: /*
385: * If datagram marked as having more fragments
386: * or if this is not the first fragment,
387: * attempt reassembly; if it succeeds, proceed.
388: */
389: if (((struct ipasfrag *)ip)->ipf_mff || ip->ip_off) {
390: ipstat.ips_fragments++;
391: ip = ip_reass((struct ipasfrag *)ip, fp);
392: if (ip == 0)
393: goto next;
394: else
395: ipstat.ips_reassembled++;
396: m = dtom(ip);
397: } else
398: if (fp)
399: ip_freef(fp);
400: } else
401: ip->ip_len -= hlen;
402:
403: /*
404: * Switch out to protocol's input routine.
405: */
406: ipstat.ips_delivered++;
407: (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
408: goto next;
409: bad:
410: m_freem(m);
411: goto next;
412: }
413:
414: /*
415: * Take incoming datagram fragment and try to
416: * reassemble it into whole datagram. If a chain for
417: * reassembly of this datagram already exists, then it
418: * is given as fp; otherwise have to make a chain.
419: */
420: struct ip *
421: ip_reass(ip, fp)
422: register struct ipasfrag *ip;
423: register struct ipq *fp;
424: {
425: register struct mbuf *m = dtom(ip);
426: register struct ipasfrag *q;
427: struct mbuf *t;
428: int hlen = ip->ip_hl << 2;
429: int i, next;
430:
431: /*
432: * Presence of header sizes in mbufs
433: * would confuse code below.
434: */
435: m->m_data += hlen;
436: m->m_len -= hlen;
437:
438: /*
439: * If first fragment to arrive, create a reassembly queue.
440: */
441: if (fp == 0) {
442: if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
443: goto dropfrag;
444: fp = mtod(t, struct ipq *);
445: insque(fp, &ipq);
446: fp->ipq_ttl = IPFRAGTTL;
447: fp->ipq_p = ip->ip_p;
448: fp->ipq_id = ip->ip_id;
449: fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp;
450: fp->ipq_src = ((struct ip *)ip)->ip_src;
451: fp->ipq_dst = ((struct ip *)ip)->ip_dst;
452: q = (struct ipasfrag *)fp;
453: goto insert;
454: }
455:
456: /*
457: * Find a segment which begins after this one does.
458: */
459: for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next)
460: if (q->ip_off > ip->ip_off)
461: break;
462:
463: /*
464: * If there is a preceding segment, it may provide some of
465: * our data already. If so, drop the data from the incoming
466: * segment. If it provides all of our data, drop us.
467: */
468: if (q->ipf_prev != (struct ipasfrag *)fp) {
469: i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off;
470: if (i > 0) {
471: if (i >= ip->ip_len)
472: goto dropfrag;
473: m_adj(dtom(ip), i);
474: ip->ip_off += i;
475: ip->ip_len -= i;
476: }
477: }
478:
479: /*
480: * While we overlap succeeding segments trim them or,
481: * if they are completely covered, dequeue them.
482: */
483: while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) {
484: i = (ip->ip_off + ip->ip_len) - q->ip_off;
485: if (i < q->ip_len) {
486: q->ip_len -= i;
487: q->ip_off += i;
488: m_adj(dtom(q), i);
489: break;
490: }
491: q = q->ipf_next;
492: m_freem(dtom(q->ipf_prev));
493: ip_deq(q->ipf_prev);
494: }
495:
496: insert:
497: /*
498: * Stick new segment in its place;
499: * check for complete reassembly.
500: */
501: ip_enq(ip, q->ipf_prev);
502: next = 0;
503: for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) {
504: if (q->ip_off != next)
505: return (0);
506: next += q->ip_len;
507: }
508: if (q->ipf_prev->ipf_mff)
509: return (0);
510:
511: /*
512: * Reassembly is complete; concatenate fragments.
513: */
514: q = fp->ipq_next;
515: m = dtom(q);
516: t = m->m_next;
517: m->m_next = 0;
518: m_cat(m, t);
519: q = q->ipf_next;
520: while (q != (struct ipasfrag *)fp) {
521: t = dtom(q);
522: q = q->ipf_next;
523: m_cat(m, t);
524: }
525:
526: /*
527: * Create header for new ip packet by
528: * modifying header of first packet;
529: * dequeue and discard fragment reassembly header.
530: * Make header visible.
531: */
532: ip = fp->ipq_next;
533: ip->ip_len = next;
534: ((struct ip *)ip)->ip_src = fp->ipq_src;
535: ((struct ip *)ip)->ip_dst = fp->ipq_dst;
536: remque(fp);
537: (void) m_free(dtom(fp));
538: m = dtom(ip);
539: m->m_len += (ip->ip_hl << 2);
540: m->m_data -= (ip->ip_hl << 2);
541: /* some debugging cruft by sklower, below, will go away soon */
542: if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
543: register int plen = 0;
544: for (t = m; m; m = m->m_next)
545: plen += m->m_len;
546: t->m_pkthdr.len = plen;
547: }
548: return ((struct ip *)ip);
549:
550: dropfrag:
551: ipstat.ips_fragdropped++;
552: m_freem(m);
553: return (0);
554: }
555:
556: /*
557: * Free a fragment reassembly header and all
558: * associated datagrams.
559: */
1.8 mycroft 560: void
1.1 cgd 561: ip_freef(fp)
562: struct ipq *fp;
563: {
564: register struct ipasfrag *q, *p;
565:
566: for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) {
567: p = q->ipf_next;
568: ip_deq(q);
569: m_freem(dtom(q));
570: }
571: remque(fp);
572: (void) m_free(dtom(fp));
573: }
574:
575: /*
576: * Put an ip fragment on a reassembly chain.
577: * Like insque, but pointers in middle of structure.
578: */
1.8 mycroft 579: void
1.1 cgd 580: ip_enq(p, prev)
581: register struct ipasfrag *p, *prev;
582: {
583:
584: p->ipf_prev = prev;
585: p->ipf_next = prev->ipf_next;
586: prev->ipf_next->ipf_prev = p;
587: prev->ipf_next = p;
588: }
589:
590: /*
591: * To ip_enq as remque is to insque.
592: */
1.8 mycroft 593: void
1.1 cgd 594: ip_deq(p)
595: register struct ipasfrag *p;
596: {
597:
598: p->ipf_prev->ipf_next = p->ipf_next;
599: p->ipf_next->ipf_prev = p->ipf_prev;
600: }
601:
602: /*
603: * IP timer processing;
604: * if a timer expires on a reassembly
605: * queue, discard it.
606: */
1.8 mycroft 607: void
1.1 cgd 608: ip_slowtimo()
609: {
610: register struct ipq *fp;
611: int s = splnet();
612:
613: fp = ipq.next;
614: if (fp == 0) {
615: splx(s);
616: return;
617: }
618: while (fp != &ipq) {
619: --fp->ipq_ttl;
620: fp = fp->next;
621: if (fp->prev->ipq_ttl == 0) {
622: ipstat.ips_fragtimeout++;
623: ip_freef(fp->prev);
624: }
625: }
626: splx(s);
627: }
628:
629: /*
630: * Drain off all datagram fragments.
631: */
1.8 mycroft 632: void
1.1 cgd 633: ip_drain()
634: {
635:
636: while (ipq.next != &ipq) {
637: ipstat.ips_fragdropped++;
638: ip_freef(ipq.next);
639: }
640: }
641:
642: extern struct in_ifaddr *ifptoia();
643: struct in_ifaddr *ip_rtaddr();
644:
645: /*
646: * Do option processing on a datagram,
647: * possibly discarding it if bad options are encountered,
648: * or forwarding it if source-routed.
649: * Returns 1 if packet has been forwarded/freed,
650: * 0 if the packet should be processed further.
651: */
1.8 mycroft 652: int
1.1 cgd 653: ip_dooptions(m)
654: struct mbuf *m;
655: {
656: register struct ip *ip = mtod(m, struct ip *);
657: register u_char *cp;
658: register struct ip_timestamp *ipt;
659: register struct in_ifaddr *ia;
660: int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
661: struct in_addr *sin;
662: n_time ntime;
663:
664: cp = (u_char *)(ip + 1);
665: cnt = (ip->ip_hl << 2) - sizeof (struct ip);
666: for (; cnt > 0; cnt -= optlen, cp += optlen) {
667: opt = cp[IPOPT_OPTVAL];
668: if (opt == IPOPT_EOL)
669: break;
670: if (opt == IPOPT_NOP)
671: optlen = 1;
672: else {
673: optlen = cp[IPOPT_OLEN];
674: if (optlen <= 0 || optlen > cnt) {
675: code = &cp[IPOPT_OLEN] - (u_char *)ip;
676: goto bad;
677: }
678: }
679: switch (opt) {
680:
681: default:
682: break;
683:
684: /*
685: * Source routing with record.
686: * Find interface with current destination address.
687: * If none on this machine then drop if strictly routed,
688: * or do nothing if loosely routed.
689: * Record interface address and bring up next address
690: * component. If strictly routed make sure next
691: * address is on directly accessible net.
692: */
693: case IPOPT_LSRR:
694: case IPOPT_SSRR:
695: if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
696: code = &cp[IPOPT_OFFSET] - (u_char *)ip;
697: goto bad;
698: }
699: ipaddr.sin_addr = ip->ip_dst;
700: ia = (struct in_ifaddr *)
701: ifa_ifwithaddr((struct sockaddr *)&ipaddr);
702: if (ia == 0) {
703: if (opt == IPOPT_SSRR) {
704: type = ICMP_UNREACH;
705: code = ICMP_UNREACH_SRCFAIL;
706: goto bad;
707: }
708: /*
709: * Loose routing, and not at next destination
710: * yet; nothing to do except forward.
711: */
712: break;
713: }
714: off--; /* 0 origin */
715: if (off > optlen - sizeof(struct in_addr)) {
716: /*
717: * End of source route. Should be for us.
718: */
719: save_rte(cp, ip->ip_src);
720: break;
721: }
722: /*
723: * locate outgoing interface
724: */
725: bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
726: sizeof(ipaddr.sin_addr));
727: if (opt == IPOPT_SSRR) {
728: #define INA struct in_ifaddr *
729: #define SA struct sockaddr *
730: if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
731: ia = in_iaonnetof(in_netof(ipaddr.sin_addr));
732: } else
733: ia = ip_rtaddr(ipaddr.sin_addr);
734: if (ia == 0) {
735: type = ICMP_UNREACH;
736: code = ICMP_UNREACH_SRCFAIL;
737: goto bad;
738: }
739: ip->ip_dst = ipaddr.sin_addr;
740: bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
741: (caddr_t)(cp + off), sizeof(struct in_addr));
742: cp[IPOPT_OFFSET] += sizeof(struct in_addr);
743: forward = 1;
744: break;
745:
746: case IPOPT_RR:
747: if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
748: code = &cp[IPOPT_OFFSET] - (u_char *)ip;
749: goto bad;
750: }
751: /*
752: * If no space remains, ignore.
753: */
754: off--; /* 0 origin */
755: if (off > optlen - sizeof(struct in_addr))
756: break;
757: bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
758: sizeof(ipaddr.sin_addr));
759: /*
760: * locate outgoing interface; if we're the destination,
761: * use the incoming interface (should be same).
762: */
763: if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
764: (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
765: type = ICMP_UNREACH;
766: code = ICMP_UNREACH_HOST;
767: goto bad;
768: }
769: bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
770: (caddr_t)(cp + off), sizeof(struct in_addr));
771: cp[IPOPT_OFFSET] += sizeof(struct in_addr);
772: break;
773:
774: case IPOPT_TS:
775: code = cp - (u_char *)ip;
776: ipt = (struct ip_timestamp *)cp;
777: if (ipt->ipt_len < 5)
778: goto bad;
779: if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) {
780: if (++ipt->ipt_oflw == 0)
781: goto bad;
782: break;
783: }
784: sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
785: switch (ipt->ipt_flg) {
786:
787: case IPOPT_TS_TSONLY:
788: break;
789:
790: case IPOPT_TS_TSANDADDR:
791: if (ipt->ipt_ptr + sizeof(n_time) +
792: sizeof(struct in_addr) > ipt->ipt_len)
793: goto bad;
794: ia = ifptoia(m->m_pkthdr.rcvif);
795: bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
796: (caddr_t)sin, sizeof(struct in_addr));
797: ipt->ipt_ptr += sizeof(struct in_addr);
798: break;
799:
800: case IPOPT_TS_PRESPEC:
801: if (ipt->ipt_ptr + sizeof(n_time) +
802: sizeof(struct in_addr) > ipt->ipt_len)
803: goto bad;
804: bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
805: sizeof(struct in_addr));
806: if (ifa_ifwithaddr((SA)&ipaddr) == 0)
807: continue;
808: ipt->ipt_ptr += sizeof(struct in_addr);
809: break;
810:
811: default:
812: goto bad;
813: }
814: ntime = iptime();
815: bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
816: sizeof(n_time));
817: ipt->ipt_ptr += sizeof(n_time);
818: }
819: }
820: if (forward) {
821: ip_forward(m, 1);
822: return (1);
823: } else
824: return (0);
825: bad:
1.7 mycroft 826: {
827: register struct in_addr foo = {};
828: icmp_error(m, type, code, foo);
829: }
1.1 cgd 830: return (1);
831: }
832:
833: /*
834: * Given address of next destination (final or next hop),
835: * return internet address info of interface to be used to get there.
836: */
837: struct in_ifaddr *
838: ip_rtaddr(dst)
839: struct in_addr dst;
840: {
841: register struct sockaddr_in *sin;
842:
843: sin = (struct sockaddr_in *) &ipforward_rt.ro_dst;
844:
845: if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) {
846: if (ipforward_rt.ro_rt) {
847: RTFREE(ipforward_rt.ro_rt);
848: ipforward_rt.ro_rt = 0;
849: }
850: sin->sin_family = AF_INET;
851: sin->sin_len = sizeof(*sin);
852: sin->sin_addr = dst;
853:
854: rtalloc(&ipforward_rt);
855: }
856: if (ipforward_rt.ro_rt == 0)
857: return ((struct in_ifaddr *)0);
858: return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa);
859: }
860:
861: /*
862: * Save incoming source route for use in replies,
863: * to be picked up later by ip_srcroute if the receiver is interested.
864: */
1.8 mycroft 865: static void
1.1 cgd 866: save_rte(option, dst)
867: u_char *option;
868: struct in_addr dst;
869: {
870: unsigned olen;
871:
872: olen = option[IPOPT_OLEN];
873: #ifdef DIAGNOSTIC
874: if (ipprintfs)
875: printf("save_rte: olen %d\n", olen);
876: #endif
877: if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
878: return;
879: bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen);
880: ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
881: ip_srcrt.dst = dst;
882: }
883:
884: /*
885: * Retrieve incoming source route for use in replies,
886: * in the same form used by setsockopt.
887: * The first hop is placed before the options, will be removed later.
888: */
889: struct mbuf *
890: ip_srcroute()
891: {
892: register struct in_addr *p, *q;
893: register struct mbuf *m;
894:
895: if (ip_nhops == 0)
896: return ((struct mbuf *)0);
897: m = m_get(M_DONTWAIT, MT_SOOPTS);
898: if (m == 0)
899: return ((struct mbuf *)0);
900:
1.6 mycroft 901: #define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
1.1 cgd 902:
903: /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
904: m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
905: OPTSIZ;
906: #ifdef DIAGNOSTIC
907: if (ipprintfs)
908: printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
909: #endif
910:
911: /*
912: * First save first hop for return route
913: */
914: p = &ip_srcrt.route[ip_nhops - 1];
915: *(mtod(m, struct in_addr *)) = *p--;
916: #ifdef DIAGNOSTIC
917: if (ipprintfs)
918: printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr));
919: #endif
920:
921: /*
922: * Copy option fields and padding (nop) to mbuf.
923: */
924: ip_srcrt.nop = IPOPT_NOP;
925: ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
926: bcopy((caddr_t)&ip_srcrt.nop,
927: mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ);
928: q = (struct in_addr *)(mtod(m, caddr_t) +
929: sizeof(struct in_addr) + OPTSIZ);
930: #undef OPTSIZ
931: /*
932: * Record return path as an IP source route,
933: * reversing the path (pointers are now aligned).
934: */
935: while (p >= ip_srcrt.route) {
936: #ifdef DIAGNOSTIC
937: if (ipprintfs)
938: printf(" %lx", ntohl(q->s_addr));
939: #endif
940: *q++ = *p--;
941: }
942: /*
943: * Last hop goes to final destination.
944: */
945: *q = ip_srcrt.dst;
946: #ifdef DIAGNOSTIC
947: if (ipprintfs)
948: printf(" %lx\n", ntohl(q->s_addr));
949: #endif
950: return (m);
951: }
952:
953: /*
954: * Strip out IP options, at higher
955: * level protocol in the kernel.
956: * Second argument is buffer to which options
957: * will be moved, and return value is their length.
958: * XXX should be deleted; last arg currently ignored.
959: */
1.8 mycroft 960: void
1.1 cgd 961: ip_stripoptions(m, mopt)
962: register struct mbuf *m;
963: struct mbuf *mopt;
964: {
965: register int i;
966: struct ip *ip = mtod(m, struct ip *);
967: register caddr_t opts;
968: int olen;
969:
970: olen = (ip->ip_hl<<2) - sizeof (struct ip);
971: opts = (caddr_t)(ip + 1);
972: i = m->m_len - (sizeof (struct ip) + olen);
973: bcopy(opts + olen, opts, (unsigned)i);
974: m->m_len -= olen;
975: if (m->m_flags & M_PKTHDR)
976: m->m_pkthdr.len -= olen;
977: ip->ip_hl = sizeof(struct ip) >> 2;
978: }
979:
980: u_char inetctlerrmap[PRC_NCMDS] = {
981: 0, 0, 0, 0,
982: 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH,
983: EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED,
984: EMSGSIZE, EHOSTUNREACH, 0, 0,
985: 0, 0, 0, 0,
986: ENOPROTOOPT
987: };
988:
989: /*
990: * Forward a packet. If some error occurs return the sender
991: * an icmp packet. Note we can't always generate a meaningful
992: * icmp message because icmp doesn't have a large enough repertoire
993: * of codes and types.
994: *
995: * If not forwarding, just drop the packet. This could be confusing
996: * if ipforwarding was zero but some routing protocol was advancing
997: * us as a gateway to somewhere. However, we must let the routing
998: * protocol deal with that.
999: *
1000: * The srcrt parameter indicates whether the packet is being forwarded
1001: * via a source route.
1002: */
1.8 mycroft 1003: static void
1.1 cgd 1004: ip_forward(m, srcrt)
1005: struct mbuf *m;
1006: int srcrt;
1007: {
1008: register struct ip *ip = mtod(m, struct ip *);
1009: register struct sockaddr_in *sin;
1010: register struct rtentry *rt;
1011: int error, type = 0, code;
1012: struct mbuf *mcopy;
1013: struct in_addr dest;
1014:
1015: dest.s_addr = 0;
1016: #ifdef DIAGNOSTIC
1017: if (ipprintfs)
1018: printf("forward: src %x dst %x ttl %x\n", ip->ip_src,
1019: ip->ip_dst, ip->ip_ttl);
1020: #endif
1021: if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) {
1022: ipstat.ips_cantforward++;
1023: m_freem(m);
1024: return;
1025: }
1026: HTONS(ip->ip_id);
1027: if (ip->ip_ttl <= IPTTLDEC) {
1028: icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest);
1029: return;
1030: }
1031: ip->ip_ttl -= IPTTLDEC;
1032:
1033: sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
1034: if ((rt = ipforward_rt.ro_rt) == 0 ||
1035: ip->ip_dst.s_addr != sin->sin_addr.s_addr) {
1036: if (ipforward_rt.ro_rt) {
1037: RTFREE(ipforward_rt.ro_rt);
1038: ipforward_rt.ro_rt = 0;
1039: }
1040: sin->sin_family = AF_INET;
1041: sin->sin_len = sizeof(*sin);
1042: sin->sin_addr = ip->ip_dst;
1043:
1044: rtalloc(&ipforward_rt);
1045: if (ipforward_rt.ro_rt == 0) {
1046: icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest);
1047: return;
1048: }
1049: rt = ipforward_rt.ro_rt;
1050: }
1051:
1052: /*
1053: * Save at most 64 bytes of the packet in case
1054: * we need to generate an ICMP message to the src.
1055: */
1056: mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64));
1057:
1058: #ifdef GATEWAY
1059: ip_ifmatrix[rt->rt_ifp->if_index +
1060: if_index * m->m_pkthdr.rcvif->if_index]++;
1061: #endif
1062: /*
1063: * If forwarding packet using same interface that it came in on,
1064: * perhaps should send a redirect to sender to shortcut a hop.
1065: * Only send redirect if source is sending directly to us,
1066: * and if packet was not source routed (or has any options).
1067: * Also, don't send redirect if forwarding using a default route
1068: * or a route modified by a redirect.
1069: */
1070: #define satosin(sa) ((struct sockaddr_in *)(sa))
1071: if (rt->rt_ifp == m->m_pkthdr.rcvif &&
1072: (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1073: satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
1074: ipsendredirects && !srcrt) {
1075: struct in_ifaddr *ia;
1076: u_long src = ntohl(ip->ip_src.s_addr);
1077: u_long dst = ntohl(ip->ip_dst.s_addr);
1078:
1079: if ((ia = ifptoia(m->m_pkthdr.rcvif)) &&
1080: (src & ia->ia_subnetmask) == ia->ia_subnet) {
1081: if (rt->rt_flags & RTF_GATEWAY)
1082: dest = satosin(rt->rt_gateway)->sin_addr;
1083: else
1084: dest = ip->ip_dst;
1085: /*
1086: * If the destination is reached by a route to host,
1087: * is on a subnet of a local net, or is directly
1088: * on the attached net (!), use host redirect.
1089: * (We may be the correct first hop for other subnets.)
1090: */
1091: #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
1092: type = ICMP_REDIRECT;
1093: if ((rt->rt_flags & RTF_HOST) ||
1094: (rt->rt_flags & RTF_GATEWAY) == 0)
1095: code = ICMP_REDIRECT_HOST;
1096: else if (RTA(rt)->ia_subnetmask != RTA(rt)->ia_netmask &&
1097: (dst & RTA(rt)->ia_netmask) == RTA(rt)->ia_net)
1098: code = ICMP_REDIRECT_HOST;
1099: else
1100: code = ICMP_REDIRECT_NET;
1101: #ifdef DIAGNOSTIC
1102: if (ipprintfs)
1103: printf("redirect (%d) to %x\n", code, dest.s_addr);
1104: #endif
1105: }
1106: }
1107:
1.9 mycroft 1108: error = ip_output(m, NULL, &ipforward_rt, IP_FORWARDING
1109: #ifdef DIRECTED_BROADCAST
1110: | IP_ALLOWBROADCAST
1111: #endif
1112: , NULL);
1.1 cgd 1113: if (error)
1114: ipstat.ips_cantforward++;
1115: else {
1116: ipstat.ips_forward++;
1117: if (type)
1118: ipstat.ips_redirectsent++;
1119: else {
1120: if (mcopy)
1121: m_freem(mcopy);
1122: return;
1123: }
1124: }
1125: if (mcopy == NULL)
1126: return;
1127: switch (error) {
1128:
1129: case 0: /* forwarded, but need redirect */
1130: /* type, code set above */
1131: break;
1132:
1133: case ENETUNREACH: /* shouldn't happen, checked above */
1134: case EHOSTUNREACH:
1135: case ENETDOWN:
1136: case EHOSTDOWN:
1137: default:
1138: type = ICMP_UNREACH;
1139: code = ICMP_UNREACH_HOST;
1140: break;
1141:
1142: case EMSGSIZE:
1143: type = ICMP_UNREACH;
1144: code = ICMP_UNREACH_NEEDFRAG;
1145: ipstat.ips_cantfrag++;
1146: break;
1147:
1148: case ENOBUFS:
1149: type = ICMP_SOURCEQUENCH;
1150: code = 0;
1151: break;
1152: }
1153: icmp_error(mcopy, type, code, dest);
1154: }
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