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