Annotation of src/sys/netinet/ip_input.c, Revision 1.1.1.1
1.1 cgd 1: /*
2: * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
3: * All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: * 3. All advertising materials mentioning features or use of this software
14: * must display the following acknowledgement:
15: * This product includes software developed by the University of
16: * California, Berkeley and its contributors.
17: * 4. Neither the name of the University nor the names of its contributors
18: * may be used to endorse or promote products derived from this software
19: * without specific prior written permission.
20: *
21: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31: * SUCH DAMAGE.
32: *
33: * @(#)ip_input.c 7.19 (Berkeley) 5/25/91
34: */
35:
36: #include "param.h"
37: #include "systm.h"
38: #include "malloc.h"
39: #include "mbuf.h"
40: #include "domain.h"
41: #include "protosw.h"
42: #include "socket.h"
43: #include "errno.h"
44: #include "time.h"
45: #include "kernel.h"
46:
47: #include "../net/if.h"
48: #include "../net/route.h"
49:
50: #include "in.h"
51: #include "in_systm.h"
52: #include "ip.h"
53: #include "in_pcb.h"
54: #include "in_var.h"
55: #include "ip_var.h"
56: #include "ip_icmp.h"
57:
58: #ifndef IPFORWARDING
59: #ifdef GATEWAY
60: #define IPFORWARDING 1 /* forward IP packets not for us */
61: #else /* GATEWAY */
62: #define IPFORWARDING 0 /* don't forward IP packets not for us */
63: #endif /* GATEWAY */
64: #endif /* IPFORWARDING */
65: #ifndef IPSENDREDIRECTS
66: #define IPSENDREDIRECTS 1
67: #endif
68: int ipforwarding = IPFORWARDING;
69: int ipsendredirects = IPSENDREDIRECTS;
70: #ifdef DIAGNOSTIC
71: int ipprintfs = 0;
72: #endif
73:
74: extern struct domain inetdomain;
75: extern struct protosw inetsw[];
76: u_char ip_protox[IPPROTO_MAX];
77: int ipqmaxlen = IFQ_MAXLEN;
78: struct in_ifaddr *in_ifaddr; /* first inet address */
79:
80: /*
81: * We need to save the IP options in case a protocol wants to respond
82: * to an incoming packet over the same route if the packet got here
83: * using IP source routing. This allows connection establishment and
84: * maintenance when the remote end is on a network that is not known
85: * to us.
86: */
87: int ip_nhops = 0;
88: static struct ip_srcrt {
89: struct in_addr dst; /* final destination */
90: char nop; /* one NOP to align */
91: char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */
92: struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
93: } ip_srcrt;
94:
95: #ifdef GATEWAY
96: extern int if_index;
97: u_long *ip_ifmatrix;
98: #endif
99:
100: /*
101: * IP initialization: fill in IP protocol switch table.
102: * All protocols not implemented in kernel go to raw IP protocol handler.
103: */
104: ip_init()
105: {
106: register struct protosw *pr;
107: register int i;
108:
109: pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
110: if (pr == 0)
111: panic("ip_init");
112: for (i = 0; i < IPPROTO_MAX; i++)
113: ip_protox[i] = pr - inetsw;
114: for (pr = inetdomain.dom_protosw;
115: pr < inetdomain.dom_protoswNPROTOSW; pr++)
116: if (pr->pr_domain->dom_family == PF_INET &&
117: pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
118: ip_protox[pr->pr_protocol] = pr - inetsw;
119: ipq.next = ipq.prev = &ipq;
120: ip_id = time.tv_sec & 0xffff;
121: ipintrq.ifq_maxlen = ipqmaxlen;
122: #ifdef GATEWAY
123: i = (if_index + 1) * (if_index + 1) * sizeof (u_long);
124: if ((ip_ifmatrix = (u_long *) malloc(i, M_RTABLE, M_WAITOK)) == 0)
125: panic("no memory for ip_ifmatrix");
126: #endif
127: }
128:
129: struct ip *ip_reass();
130: struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
131: struct route ipforward_rt;
132:
133: /*
134: * Ip input routine. Checksum and byte swap header. If fragmented
135: * try to reassemble. Process options. Pass to next level.
136: */
137: ipintr()
138: {
139: register struct ip *ip;
140: register struct mbuf *m;
141: register struct ipq *fp;
142: register struct in_ifaddr *ia;
143: int hlen, s;
144:
145: next:
146: /*
147: * Get next datagram off input queue and get IP header
148: * in first mbuf.
149: */
150: s = splimp();
151: IF_DEQUEUE(&ipintrq, m);
152: splx(s);
153: if (m == 0)
154: return;
155: #ifdef DIAGNOSTIC
156: if ((m->m_flags & M_PKTHDR) == 0)
157: panic("ipintr no HDR");
158: #endif
159: /*
160: * If no IP addresses have been set yet but the interfaces
161: * are receiving, can't do anything with incoming packets yet.
162: */
163: if (in_ifaddr == NULL)
164: goto bad;
165: ipstat.ips_total++;
166: if (m->m_len < sizeof (struct ip) &&
167: (m = m_pullup(m, sizeof (struct ip))) == 0) {
168: ipstat.ips_toosmall++;
169: goto next;
170: }
171: ip = mtod(m, struct ip *);
172: hlen = ip->ip_hl << 2;
173: if (hlen < sizeof(struct ip)) { /* minimum header length */
174: ipstat.ips_badhlen++;
175: goto bad;
176: }
177: if (hlen > m->m_len) {
178: if ((m = m_pullup(m, hlen)) == 0) {
179: ipstat.ips_badhlen++;
180: goto next;
181: }
182: ip = mtod(m, struct ip *);
183: }
184: if (ip->ip_sum = in_cksum(m, hlen)) {
185: ipstat.ips_badsum++;
186: goto bad;
187: }
188:
189: /*
190: * Convert fields to host representation.
191: */
192: NTOHS(ip->ip_len);
193: if (ip->ip_len < hlen) {
194: ipstat.ips_badlen++;
195: goto bad;
196: }
197: NTOHS(ip->ip_id);
198: NTOHS(ip->ip_off);
199:
200: /*
201: * Check that the amount of data in the buffers
202: * is as at least much as the IP header would have us expect.
203: * Trim mbufs if longer than we expect.
204: * Drop packet if shorter than we expect.
205: */
206: if (m->m_pkthdr.len < ip->ip_len) {
207: ipstat.ips_tooshort++;
208: goto bad;
209: }
210: if (m->m_pkthdr.len > ip->ip_len) {
211: if (m->m_len == m->m_pkthdr.len) {
212: m->m_len = ip->ip_len;
213: m->m_pkthdr.len = ip->ip_len;
214: } else
215: m_adj(m, ip->ip_len - m->m_pkthdr.len);
216: }
217:
218: /*
219: * Process options and, if not destined for us,
220: * ship it on. ip_dooptions returns 1 when an
221: * error was detected (causing an icmp message
222: * to be sent and the original packet to be freed).
223: */
224: ip_nhops = 0; /* for source routed packets */
225: if (hlen > sizeof (struct ip) && ip_dooptions(m))
226: goto next;
227:
228: /*
229: * Check our list of addresses, to see if the packet is for us.
230: */
231: for (ia = in_ifaddr; ia; ia = ia->ia_next) {
232: #define satosin(sa) ((struct sockaddr_in *)(sa))
233:
234: if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
235: goto ours;
236: if (
237: #ifdef DIRECTED_BROADCAST
238: ia->ia_ifp == m->m_pkthdr.rcvif &&
239: #endif
240: (ia->ia_ifp->if_flags & IFF_BROADCAST)) {
241: u_long t;
242:
243: if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
244: ip->ip_dst.s_addr)
245: goto ours;
246: if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr)
247: goto ours;
248: /*
249: * Look for all-0's host part (old broadcast addr),
250: * either for subnet or net.
251: */
252: t = ntohl(ip->ip_dst.s_addr);
253: if (t == ia->ia_subnet)
254: goto ours;
255: if (t == ia->ia_net)
256: goto ours;
257: }
258: }
259: if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
260: goto ours;
261: if (ip->ip_dst.s_addr == INADDR_ANY)
262: goto ours;
263:
264: /*
265: * Not for us; forward if possible and desirable.
266: */
267: if (ipforwarding == 0) {
268: ipstat.ips_cantforward++;
269: m_freem(m);
270: } else
271: ip_forward(m, 0);
272: goto next;
273:
274: ours:
275: /*
276: * If offset or IP_MF are set, must reassemble.
277: * Otherwise, nothing need be done.
278: * (We could look in the reassembly queue to see
279: * if the packet was previously fragmented,
280: * but it's not worth the time; just let them time out.)
281: */
282: if (ip->ip_off &~ IP_DF) {
283: if (m->m_flags & M_EXT) { /* XXX */
284: if ((m = m_pullup(m, sizeof (struct ip))) == 0) {
285: ipstat.ips_toosmall++;
286: goto next;
287: }
288: ip = mtod(m, struct ip *);
289: }
290: /*
291: * Look for queue of fragments
292: * of this datagram.
293: */
294: for (fp = ipq.next; fp != &ipq; fp = fp->next)
295: if (ip->ip_id == fp->ipq_id &&
296: ip->ip_src.s_addr == fp->ipq_src.s_addr &&
297: ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
298: ip->ip_p == fp->ipq_p)
299: goto found;
300: fp = 0;
301: found:
302:
303: /*
304: * Adjust ip_len to not reflect header,
305: * set ip_mff if more fragments are expected,
306: * convert offset of this to bytes.
307: */
308: ip->ip_len -= hlen;
309: ((struct ipasfrag *)ip)->ipf_mff = 0;
310: if (ip->ip_off & IP_MF)
311: ((struct ipasfrag *)ip)->ipf_mff = 1;
312: ip->ip_off <<= 3;
313:
314: /*
315: * If datagram marked as having more fragments
316: * or if this is not the first fragment,
317: * attempt reassembly; if it succeeds, proceed.
318: */
319: if (((struct ipasfrag *)ip)->ipf_mff || ip->ip_off) {
320: ipstat.ips_fragments++;
321: ip = ip_reass((struct ipasfrag *)ip, fp);
322: if (ip == 0)
323: goto next;
324: else
325: ipstat.ips_reassembled++;
326: m = dtom(ip);
327: } else
328: if (fp)
329: ip_freef(fp);
330: } else
331: ip->ip_len -= hlen;
332:
333: /*
334: * Switch out to protocol's input routine.
335: */
336: ipstat.ips_delivered++;
337: (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
338: goto next;
339: bad:
340: m_freem(m);
341: goto next;
342: }
343:
344: /*
345: * Take incoming datagram fragment and try to
346: * reassemble it into whole datagram. If a chain for
347: * reassembly of this datagram already exists, then it
348: * is given as fp; otherwise have to make a chain.
349: */
350: struct ip *
351: ip_reass(ip, fp)
352: register struct ipasfrag *ip;
353: register struct ipq *fp;
354: {
355: register struct mbuf *m = dtom(ip);
356: register struct ipasfrag *q;
357: struct mbuf *t;
358: int hlen = ip->ip_hl << 2;
359: int i, next;
360:
361: /*
362: * Presence of header sizes in mbufs
363: * would confuse code below.
364: */
365: m->m_data += hlen;
366: m->m_len -= hlen;
367:
368: /*
369: * If first fragment to arrive, create a reassembly queue.
370: */
371: if (fp == 0) {
372: if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
373: goto dropfrag;
374: fp = mtod(t, struct ipq *);
375: insque(fp, &ipq);
376: fp->ipq_ttl = IPFRAGTTL;
377: fp->ipq_p = ip->ip_p;
378: fp->ipq_id = ip->ip_id;
379: fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp;
380: fp->ipq_src = ((struct ip *)ip)->ip_src;
381: fp->ipq_dst = ((struct ip *)ip)->ip_dst;
382: q = (struct ipasfrag *)fp;
383: goto insert;
384: }
385:
386: /*
387: * Find a segment which begins after this one does.
388: */
389: for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next)
390: if (q->ip_off > ip->ip_off)
391: break;
392:
393: /*
394: * If there is a preceding segment, it may provide some of
395: * our data already. If so, drop the data from the incoming
396: * segment. If it provides all of our data, drop us.
397: */
398: if (q->ipf_prev != (struct ipasfrag *)fp) {
399: i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off;
400: if (i > 0) {
401: if (i >= ip->ip_len)
402: goto dropfrag;
403: m_adj(dtom(ip), i);
404: ip->ip_off += i;
405: ip->ip_len -= i;
406: }
407: }
408:
409: /*
410: * While we overlap succeeding segments trim them or,
411: * if they are completely covered, dequeue them.
412: */
413: while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) {
414: i = (ip->ip_off + ip->ip_len) - q->ip_off;
415: if (i < q->ip_len) {
416: q->ip_len -= i;
417: q->ip_off += i;
418: m_adj(dtom(q), i);
419: break;
420: }
421: q = q->ipf_next;
422: m_freem(dtom(q->ipf_prev));
423: ip_deq(q->ipf_prev);
424: }
425:
426: insert:
427: /*
428: * Stick new segment in its place;
429: * check for complete reassembly.
430: */
431: ip_enq(ip, q->ipf_prev);
432: next = 0;
433: for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) {
434: if (q->ip_off != next)
435: return (0);
436: next += q->ip_len;
437: }
438: if (q->ipf_prev->ipf_mff)
439: return (0);
440:
441: /*
442: * Reassembly is complete; concatenate fragments.
443: */
444: q = fp->ipq_next;
445: m = dtom(q);
446: t = m->m_next;
447: m->m_next = 0;
448: m_cat(m, t);
449: q = q->ipf_next;
450: while (q != (struct ipasfrag *)fp) {
451: t = dtom(q);
452: q = q->ipf_next;
453: m_cat(m, t);
454: }
455:
456: /*
457: * Create header for new ip packet by
458: * modifying header of first packet;
459: * dequeue and discard fragment reassembly header.
460: * Make header visible.
461: */
462: ip = fp->ipq_next;
463: ip->ip_len = next;
464: ((struct ip *)ip)->ip_src = fp->ipq_src;
465: ((struct ip *)ip)->ip_dst = fp->ipq_dst;
466: remque(fp);
467: (void) m_free(dtom(fp));
468: m = dtom(ip);
469: m->m_len += (ip->ip_hl << 2);
470: m->m_data -= (ip->ip_hl << 2);
471: /* some debugging cruft by sklower, below, will go away soon */
472: if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
473: register int plen = 0;
474: for (t = m; m; m = m->m_next)
475: plen += m->m_len;
476: t->m_pkthdr.len = plen;
477: }
478: return ((struct ip *)ip);
479:
480: dropfrag:
481: ipstat.ips_fragdropped++;
482: m_freem(m);
483: return (0);
484: }
485:
486: /*
487: * Free a fragment reassembly header and all
488: * associated datagrams.
489: */
490: ip_freef(fp)
491: struct ipq *fp;
492: {
493: register struct ipasfrag *q, *p;
494:
495: for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) {
496: p = q->ipf_next;
497: ip_deq(q);
498: m_freem(dtom(q));
499: }
500: remque(fp);
501: (void) m_free(dtom(fp));
502: }
503:
504: /*
505: * Put an ip fragment on a reassembly chain.
506: * Like insque, but pointers in middle of structure.
507: */
508: ip_enq(p, prev)
509: register struct ipasfrag *p, *prev;
510: {
511:
512: p->ipf_prev = prev;
513: p->ipf_next = prev->ipf_next;
514: prev->ipf_next->ipf_prev = p;
515: prev->ipf_next = p;
516: }
517:
518: /*
519: * To ip_enq as remque is to insque.
520: */
521: ip_deq(p)
522: register struct ipasfrag *p;
523: {
524:
525: p->ipf_prev->ipf_next = p->ipf_next;
526: p->ipf_next->ipf_prev = p->ipf_prev;
527: }
528:
529: /*
530: * IP timer processing;
531: * if a timer expires on a reassembly
532: * queue, discard it.
533: */
534: ip_slowtimo()
535: {
536: register struct ipq *fp;
537: int s = splnet();
538:
539: fp = ipq.next;
540: if (fp == 0) {
541: splx(s);
542: return;
543: }
544: while (fp != &ipq) {
545: --fp->ipq_ttl;
546: fp = fp->next;
547: if (fp->prev->ipq_ttl == 0) {
548: ipstat.ips_fragtimeout++;
549: ip_freef(fp->prev);
550: }
551: }
552: splx(s);
553: }
554:
555: /*
556: * Drain off all datagram fragments.
557: */
558: ip_drain()
559: {
560:
561: while (ipq.next != &ipq) {
562: ipstat.ips_fragdropped++;
563: ip_freef(ipq.next);
564: }
565: }
566:
567: extern struct in_ifaddr *ifptoia();
568: struct in_ifaddr *ip_rtaddr();
569:
570: /*
571: * Do option processing on a datagram,
572: * possibly discarding it if bad options are encountered,
573: * or forwarding it if source-routed.
574: * Returns 1 if packet has been forwarded/freed,
575: * 0 if the packet should be processed further.
576: */
577: ip_dooptions(m)
578: struct mbuf *m;
579: {
580: register struct ip *ip = mtod(m, struct ip *);
581: register u_char *cp;
582: register struct ip_timestamp *ipt;
583: register struct in_ifaddr *ia;
584: int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
585: struct in_addr *sin;
586: n_time ntime;
587:
588: cp = (u_char *)(ip + 1);
589: cnt = (ip->ip_hl << 2) - sizeof (struct ip);
590: for (; cnt > 0; cnt -= optlen, cp += optlen) {
591: opt = cp[IPOPT_OPTVAL];
592: if (opt == IPOPT_EOL)
593: break;
594: if (opt == IPOPT_NOP)
595: optlen = 1;
596: else {
597: optlen = cp[IPOPT_OLEN];
598: if (optlen <= 0 || optlen > cnt) {
599: code = &cp[IPOPT_OLEN] - (u_char *)ip;
600: goto bad;
601: }
602: }
603: switch (opt) {
604:
605: default:
606: break;
607:
608: /*
609: * Source routing with record.
610: * Find interface with current destination address.
611: * If none on this machine then drop if strictly routed,
612: * or do nothing if loosely routed.
613: * Record interface address and bring up next address
614: * component. If strictly routed make sure next
615: * address is on directly accessible net.
616: */
617: case IPOPT_LSRR:
618: case IPOPT_SSRR:
619: if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
620: code = &cp[IPOPT_OFFSET] - (u_char *)ip;
621: goto bad;
622: }
623: ipaddr.sin_addr = ip->ip_dst;
624: ia = (struct in_ifaddr *)
625: ifa_ifwithaddr((struct sockaddr *)&ipaddr);
626: if (ia == 0) {
627: if (opt == IPOPT_SSRR) {
628: type = ICMP_UNREACH;
629: code = ICMP_UNREACH_SRCFAIL;
630: goto bad;
631: }
632: /*
633: * Loose routing, and not at next destination
634: * yet; nothing to do except forward.
635: */
636: break;
637: }
638: off--; /* 0 origin */
639: if (off > optlen - sizeof(struct in_addr)) {
640: /*
641: * End of source route. Should be for us.
642: */
643: save_rte(cp, ip->ip_src);
644: break;
645: }
646: /*
647: * locate outgoing interface
648: */
649: bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
650: sizeof(ipaddr.sin_addr));
651: if (opt == IPOPT_SSRR) {
652: #define INA struct in_ifaddr *
653: #define SA struct sockaddr *
654: if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
655: ia = in_iaonnetof(in_netof(ipaddr.sin_addr));
656: } else
657: ia = ip_rtaddr(ipaddr.sin_addr);
658: if (ia == 0) {
659: type = ICMP_UNREACH;
660: code = ICMP_UNREACH_SRCFAIL;
661: goto bad;
662: }
663: ip->ip_dst = ipaddr.sin_addr;
664: bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
665: (caddr_t)(cp + off), sizeof(struct in_addr));
666: cp[IPOPT_OFFSET] += sizeof(struct in_addr);
667: forward = 1;
668: break;
669:
670: case IPOPT_RR:
671: if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
672: code = &cp[IPOPT_OFFSET] - (u_char *)ip;
673: goto bad;
674: }
675: /*
676: * If no space remains, ignore.
677: */
678: off--; /* 0 origin */
679: if (off > optlen - sizeof(struct in_addr))
680: break;
681: bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
682: sizeof(ipaddr.sin_addr));
683: /*
684: * locate outgoing interface; if we're the destination,
685: * use the incoming interface (should be same).
686: */
687: if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
688: (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
689: type = ICMP_UNREACH;
690: code = ICMP_UNREACH_HOST;
691: goto bad;
692: }
693: bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
694: (caddr_t)(cp + off), sizeof(struct in_addr));
695: cp[IPOPT_OFFSET] += sizeof(struct in_addr);
696: break;
697:
698: case IPOPT_TS:
699: code = cp - (u_char *)ip;
700: ipt = (struct ip_timestamp *)cp;
701: if (ipt->ipt_len < 5)
702: goto bad;
703: if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) {
704: if (++ipt->ipt_oflw == 0)
705: goto bad;
706: break;
707: }
708: sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
709: switch (ipt->ipt_flg) {
710:
711: case IPOPT_TS_TSONLY:
712: break;
713:
714: case IPOPT_TS_TSANDADDR:
715: if (ipt->ipt_ptr + sizeof(n_time) +
716: sizeof(struct in_addr) > ipt->ipt_len)
717: goto bad;
718: ia = ifptoia(m->m_pkthdr.rcvif);
719: bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
720: (caddr_t)sin, sizeof(struct in_addr));
721: ipt->ipt_ptr += sizeof(struct in_addr);
722: break;
723:
724: case IPOPT_TS_PRESPEC:
725: if (ipt->ipt_ptr + sizeof(n_time) +
726: sizeof(struct in_addr) > ipt->ipt_len)
727: goto bad;
728: bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
729: sizeof(struct in_addr));
730: if (ifa_ifwithaddr((SA)&ipaddr) == 0)
731: continue;
732: ipt->ipt_ptr += sizeof(struct in_addr);
733: break;
734:
735: default:
736: goto bad;
737: }
738: ntime = iptime();
739: bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
740: sizeof(n_time));
741: ipt->ipt_ptr += sizeof(n_time);
742: }
743: }
744: if (forward) {
745: ip_forward(m, 1);
746: return (1);
747: } else
748: return (0);
749: bad:
750: icmp_error(m, type, code);
751: return (1);
752: }
753:
754: /*
755: * Given address of next destination (final or next hop),
756: * return internet address info of interface to be used to get there.
757: */
758: struct in_ifaddr *
759: ip_rtaddr(dst)
760: struct in_addr dst;
761: {
762: register struct sockaddr_in *sin;
763:
764: sin = (struct sockaddr_in *) &ipforward_rt.ro_dst;
765:
766: if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) {
767: if (ipforward_rt.ro_rt) {
768: RTFREE(ipforward_rt.ro_rt);
769: ipforward_rt.ro_rt = 0;
770: }
771: sin->sin_family = AF_INET;
772: sin->sin_len = sizeof(*sin);
773: sin->sin_addr = dst;
774:
775: rtalloc(&ipforward_rt);
776: }
777: if (ipforward_rt.ro_rt == 0)
778: return ((struct in_ifaddr *)0);
779: return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa);
780: }
781:
782: /*
783: * Save incoming source route for use in replies,
784: * to be picked up later by ip_srcroute if the receiver is interested.
785: */
786: save_rte(option, dst)
787: u_char *option;
788: struct in_addr dst;
789: {
790: unsigned olen;
791:
792: olen = option[IPOPT_OLEN];
793: #ifdef DIAGNOSTIC
794: if (ipprintfs)
795: printf("save_rte: olen %d\n", olen);
796: #endif
797: if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
798: return;
799: bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen);
800: ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
801: ip_srcrt.dst = dst;
802: }
803:
804: /*
805: * Retrieve incoming source route for use in replies,
806: * in the same form used by setsockopt.
807: * The first hop is placed before the options, will be removed later.
808: */
809: struct mbuf *
810: ip_srcroute()
811: {
812: register struct in_addr *p, *q;
813: register struct mbuf *m;
814:
815: if (ip_nhops == 0)
816: return ((struct mbuf *)0);
817: m = m_get(M_DONTWAIT, MT_SOOPTS);
818: if (m == 0)
819: return ((struct mbuf *)0);
820:
821: #define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
822:
823: /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
824: m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
825: OPTSIZ;
826: #ifdef DIAGNOSTIC
827: if (ipprintfs)
828: printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
829: #endif
830:
831: /*
832: * First save first hop for return route
833: */
834: p = &ip_srcrt.route[ip_nhops - 1];
835: *(mtod(m, struct in_addr *)) = *p--;
836: #ifdef DIAGNOSTIC
837: if (ipprintfs)
838: printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr));
839: #endif
840:
841: /*
842: * Copy option fields and padding (nop) to mbuf.
843: */
844: ip_srcrt.nop = IPOPT_NOP;
845: ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
846: bcopy((caddr_t)&ip_srcrt.nop,
847: mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ);
848: q = (struct in_addr *)(mtod(m, caddr_t) +
849: sizeof(struct in_addr) + OPTSIZ);
850: #undef OPTSIZ
851: /*
852: * Record return path as an IP source route,
853: * reversing the path (pointers are now aligned).
854: */
855: while (p >= ip_srcrt.route) {
856: #ifdef DIAGNOSTIC
857: if (ipprintfs)
858: printf(" %lx", ntohl(q->s_addr));
859: #endif
860: *q++ = *p--;
861: }
862: /*
863: * Last hop goes to final destination.
864: */
865: *q = ip_srcrt.dst;
866: #ifdef DIAGNOSTIC
867: if (ipprintfs)
868: printf(" %lx\n", ntohl(q->s_addr));
869: #endif
870: return (m);
871: }
872:
873: /*
874: * Strip out IP options, at higher
875: * level protocol in the kernel.
876: * Second argument is buffer to which options
877: * will be moved, and return value is their length.
878: * XXX should be deleted; last arg currently ignored.
879: */
880: ip_stripoptions(m, mopt)
881: register struct mbuf *m;
882: struct mbuf *mopt;
883: {
884: register int i;
885: struct ip *ip = mtod(m, struct ip *);
886: register caddr_t opts;
887: int olen;
888:
889: olen = (ip->ip_hl<<2) - sizeof (struct ip);
890: opts = (caddr_t)(ip + 1);
891: i = m->m_len - (sizeof (struct ip) + olen);
892: bcopy(opts + olen, opts, (unsigned)i);
893: m->m_len -= olen;
894: if (m->m_flags & M_PKTHDR)
895: m->m_pkthdr.len -= olen;
896: ip->ip_hl = sizeof(struct ip) >> 2;
897: }
898:
899: u_char inetctlerrmap[PRC_NCMDS] = {
900: 0, 0, 0, 0,
901: 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH,
902: EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED,
903: EMSGSIZE, EHOSTUNREACH, 0, 0,
904: 0, 0, 0, 0,
905: ENOPROTOOPT
906: };
907:
908: /*
909: * Forward a packet. If some error occurs return the sender
910: * an icmp packet. Note we can't always generate a meaningful
911: * icmp message because icmp doesn't have a large enough repertoire
912: * of codes and types.
913: *
914: * If not forwarding, just drop the packet. This could be confusing
915: * if ipforwarding was zero but some routing protocol was advancing
916: * us as a gateway to somewhere. However, we must let the routing
917: * protocol deal with that.
918: *
919: * The srcrt parameter indicates whether the packet is being forwarded
920: * via a source route.
921: */
922: ip_forward(m, srcrt)
923: struct mbuf *m;
924: int srcrt;
925: {
926: register struct ip *ip = mtod(m, struct ip *);
927: register struct sockaddr_in *sin;
928: register struct rtentry *rt;
929: int error, type = 0, code;
930: struct mbuf *mcopy;
931: struct in_addr dest;
932:
933: dest.s_addr = 0;
934: #ifdef DIAGNOSTIC
935: if (ipprintfs)
936: printf("forward: src %x dst %x ttl %x\n", ip->ip_src,
937: ip->ip_dst, ip->ip_ttl);
938: #endif
939: if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) {
940: ipstat.ips_cantforward++;
941: m_freem(m);
942: return;
943: }
944: HTONS(ip->ip_id);
945: if (ip->ip_ttl <= IPTTLDEC) {
946: icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest);
947: return;
948: }
949: ip->ip_ttl -= IPTTLDEC;
950:
951: sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
952: if ((rt = ipforward_rt.ro_rt) == 0 ||
953: ip->ip_dst.s_addr != sin->sin_addr.s_addr) {
954: if (ipforward_rt.ro_rt) {
955: RTFREE(ipforward_rt.ro_rt);
956: ipforward_rt.ro_rt = 0;
957: }
958: sin->sin_family = AF_INET;
959: sin->sin_len = sizeof(*sin);
960: sin->sin_addr = ip->ip_dst;
961:
962: rtalloc(&ipforward_rt);
963: if (ipforward_rt.ro_rt == 0) {
964: icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest);
965: return;
966: }
967: rt = ipforward_rt.ro_rt;
968: }
969:
970: /*
971: * Save at most 64 bytes of the packet in case
972: * we need to generate an ICMP message to the src.
973: */
974: mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64));
975:
976: #ifdef GATEWAY
977: ip_ifmatrix[rt->rt_ifp->if_index +
978: if_index * m->m_pkthdr.rcvif->if_index]++;
979: #endif
980: /*
981: * If forwarding packet using same interface that it came in on,
982: * perhaps should send a redirect to sender to shortcut a hop.
983: * Only send redirect if source is sending directly to us,
984: * and if packet was not source routed (or has any options).
985: * Also, don't send redirect if forwarding using a default route
986: * or a route modified by a redirect.
987: */
988: #define satosin(sa) ((struct sockaddr_in *)(sa))
989: if (rt->rt_ifp == m->m_pkthdr.rcvif &&
990: (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
991: satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
992: ipsendredirects && !srcrt) {
993: struct in_ifaddr *ia;
994: u_long src = ntohl(ip->ip_src.s_addr);
995: u_long dst = ntohl(ip->ip_dst.s_addr);
996:
997: if ((ia = ifptoia(m->m_pkthdr.rcvif)) &&
998: (src & ia->ia_subnetmask) == ia->ia_subnet) {
999: if (rt->rt_flags & RTF_GATEWAY)
1000: dest = satosin(rt->rt_gateway)->sin_addr;
1001: else
1002: dest = ip->ip_dst;
1003: /*
1004: * If the destination is reached by a route to host,
1005: * is on a subnet of a local net, or is directly
1006: * on the attached net (!), use host redirect.
1007: * (We may be the correct first hop for other subnets.)
1008: */
1009: #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
1010: type = ICMP_REDIRECT;
1011: if ((rt->rt_flags & RTF_HOST) ||
1012: (rt->rt_flags & RTF_GATEWAY) == 0)
1013: code = ICMP_REDIRECT_HOST;
1014: else if (RTA(rt)->ia_subnetmask != RTA(rt)->ia_netmask &&
1015: (dst & RTA(rt)->ia_netmask) == RTA(rt)->ia_net)
1016: code = ICMP_REDIRECT_HOST;
1017: else
1018: code = ICMP_REDIRECT_NET;
1019: #ifdef DIAGNOSTIC
1020: if (ipprintfs)
1021: printf("redirect (%d) to %x\n", code, dest.s_addr);
1022: #endif
1023: }
1024: }
1025:
1026: error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING);
1027: if (error)
1028: ipstat.ips_cantforward++;
1029: else {
1030: ipstat.ips_forward++;
1031: if (type)
1032: ipstat.ips_redirectsent++;
1033: else {
1034: if (mcopy)
1035: m_freem(mcopy);
1036: return;
1037: }
1038: }
1039: if (mcopy == NULL)
1040: return;
1041: switch (error) {
1042:
1043: case 0: /* forwarded, but need redirect */
1044: /* type, code set above */
1045: break;
1046:
1047: case ENETUNREACH: /* shouldn't happen, checked above */
1048: case EHOSTUNREACH:
1049: case ENETDOWN:
1050: case EHOSTDOWN:
1051: default:
1052: type = ICMP_UNREACH;
1053: code = ICMP_UNREACH_HOST;
1054: break;
1055:
1056: case EMSGSIZE:
1057: type = ICMP_UNREACH;
1058: code = ICMP_UNREACH_NEEDFRAG;
1059: ipstat.ips_cantfrag++;
1060: break;
1061:
1062: case ENOBUFS:
1063: type = ICMP_SOURCEQUENCH;
1064: code = 0;
1065: break;
1066: }
1067: icmp_error(mcopy, type, code, dest);
1068: }
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