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