Annotation of src/sys/netinet/ip_input.c, Revision 1.3.4.1
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: *
1.3 cgd 33: * from: @(#)ip_input.c 7.19 (Berkeley) 5/25/91
1.3.4.1 ! mycroft 34: * $Id: ip_input.c,v 1.3 1993/05/20 03:50:25 cgd Exp $
1.1 cgd 35: */
36:
37: #include "param.h"
38: #include "systm.h"
39: #include "malloc.h"
40: #include "mbuf.h"
41: #include "domain.h"
42: #include "protosw.h"
43: #include "socket.h"
44: #include "errno.h"
45: #include "time.h"
46: #include "kernel.h"
1.3.4.1 ! mycroft 47:
! 48: #include "machine/cpu.h"
1.1 cgd 49:
50: #include "../net/if.h"
51: #include "../net/route.h"
52:
53: #include "in.h"
54: #include "in_systm.h"
55: #include "ip.h"
56: #include "in_pcb.h"
57: #include "in_var.h"
58: #include "ip_var.h"
59: #include "ip_icmp.h"
60:
61: #ifndef IPFORWARDING
62: #ifdef GATEWAY
63: #define IPFORWARDING 1 /* forward IP packets not for us */
64: #else /* GATEWAY */
65: #define IPFORWARDING 0 /* don't forward IP packets not for us */
66: #endif /* GATEWAY */
67: #endif /* IPFORWARDING */
68: #ifndef IPSENDREDIRECTS
69: #define IPSENDREDIRECTS 1
70: #endif
71: int ipforwarding = IPFORWARDING;
72: int ipsendredirects = IPSENDREDIRECTS;
73: #ifdef DIAGNOSTIC
74: int ipprintfs = 0;
75: #endif
76:
77: extern struct domain inetdomain;
78: extern struct protosw inetsw[];
79: u_char ip_protox[IPPROTO_MAX];
80: int ipqmaxlen = IFQ_MAXLEN;
81: struct in_ifaddr *in_ifaddr; /* first inet address */
82:
83: /*
84: * We need to save the IP options in case a protocol wants to respond
85: * to an incoming packet over the same route if the packet got here
86: * using IP source routing. This allows connection establishment and
87: * maintenance when the remote end is on a network that is not known
88: * to us.
89: */
90: int ip_nhops = 0;
91: static struct ip_srcrt {
92: struct in_addr dst; /* final destination */
93: char nop; /* one NOP to align */
94: char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */
95: struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
96: } ip_srcrt;
97:
98: #ifdef GATEWAY
99: extern int if_index;
100: u_long *ip_ifmatrix;
101: #endif
102:
103: /*
104: * IP initialization: fill in IP protocol switch table.
105: * All protocols not implemented in kernel go to raw IP protocol handler.
106: */
107: ip_init()
108: {
109: register struct protosw *pr;
110: register int i;
111:
112: pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
113: if (pr == 0)
114: panic("ip_init");
115: for (i = 0; i < IPPROTO_MAX; i++)
116: ip_protox[i] = pr - inetsw;
117: for (pr = inetdomain.dom_protosw;
118: pr < inetdomain.dom_protoswNPROTOSW; pr++)
119: if (pr->pr_domain->dom_family == PF_INET &&
120: pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
121: ip_protox[pr->pr_protocol] = pr - inetsw;
122: ipq.next = ipq.prev = &ipq;
123: ip_id = time.tv_sec & 0xffff;
124: ipintrq.ifq_maxlen = ipqmaxlen;
125: #ifdef GATEWAY
126: i = (if_index + 1) * (if_index + 1) * sizeof (u_long);
127: if ((ip_ifmatrix = (u_long *) malloc(i, M_RTABLE, M_WAITOK)) == 0)
128: panic("no memory for ip_ifmatrix");
129: #endif
130: }
131:
132: struct ip *ip_reass();
133: struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
134: struct route ipforward_rt;
135:
136: /*
137: * Ip input routine. Checksum and byte swap header. If fragmented
138: * try to reassemble. Process options. Pass to next level.
139: */
140: ipintr()
141: {
142: register struct ip *ip;
143: register struct mbuf *m;
144: register struct ipq *fp;
145: register struct in_ifaddr *ia;
146: int hlen, s;
1.2 cgd 147: #ifdef PARANOID
148: static int busy = 0;
1.1 cgd 149:
1.2 cgd 150: if (busy)
151: panic("ipintr: called recursively\n");
152: ++busy;
153: #endif
1.1 cgd 154: next:
155: /*
156: * Get next datagram off input queue and get IP header
157: * in first mbuf.
158: */
159: s = splimp();
160: IF_DEQUEUE(&ipintrq, m);
161: splx(s);
1.2 cgd 162: if (m == 0) {
163: #ifdef PARANOID
164: --busy;
165: #endif
1.1 cgd 166: return;
1.2 cgd 167: }
1.1 cgd 168: #ifdef DIAGNOSTIC
169: if ((m->m_flags & M_PKTHDR) == 0)
170: panic("ipintr no HDR");
171: #endif
172: /*
173: * If no IP addresses have been set yet but the interfaces
174: * are receiving, can't do anything with incoming packets yet.
175: */
176: if (in_ifaddr == NULL)
177: goto bad;
178: ipstat.ips_total++;
179: if (m->m_len < sizeof (struct ip) &&
180: (m = m_pullup(m, sizeof (struct ip))) == 0) {
181: ipstat.ips_toosmall++;
182: goto next;
183: }
184: ip = mtod(m, struct ip *);
185: hlen = ip->ip_hl << 2;
186: if (hlen < sizeof(struct ip)) { /* minimum header length */
187: ipstat.ips_badhlen++;
188: goto bad;
189: }
190: if (hlen > m->m_len) {
191: if ((m = m_pullup(m, hlen)) == 0) {
192: ipstat.ips_badhlen++;
193: goto next;
194: }
195: ip = mtod(m, struct ip *);
196: }
197: if (ip->ip_sum = in_cksum(m, hlen)) {
198: ipstat.ips_badsum++;
199: goto bad;
200: }
201:
202: /*
203: * Convert fields to host representation.
204: */
205: NTOHS(ip->ip_len);
206: if (ip->ip_len < hlen) {
207: ipstat.ips_badlen++;
208: goto bad;
209: }
210: NTOHS(ip->ip_id);
211: NTOHS(ip->ip_off);
212:
213: /*
214: * Check that the amount of data in the buffers
215: * is as at least much as the IP header would have us expect.
216: * Trim mbufs if longer than we expect.
217: * Drop packet if shorter than we expect.
218: */
219: if (m->m_pkthdr.len < ip->ip_len) {
220: ipstat.ips_tooshort++;
221: goto bad;
222: }
223: if (m->m_pkthdr.len > ip->ip_len) {
224: if (m->m_len == m->m_pkthdr.len) {
225: m->m_len = ip->ip_len;
226: m->m_pkthdr.len = ip->ip_len;
227: } else
228: m_adj(m, ip->ip_len - m->m_pkthdr.len);
229: }
230:
231: /*
232: * Process options and, if not destined for us,
233: * ship it on. ip_dooptions returns 1 when an
234: * error was detected (causing an icmp message
235: * to be sent and the original packet to be freed).
236: */
237: ip_nhops = 0; /* for source routed packets */
238: if (hlen > sizeof (struct ip) && ip_dooptions(m))
239: goto next;
240:
241: /*
242: * Check our list of addresses, to see if the packet is for us.
243: */
244: for (ia = in_ifaddr; ia; ia = ia->ia_next) {
245: #define satosin(sa) ((struct sockaddr_in *)(sa))
246:
247: if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
248: goto ours;
249: if (
250: #ifdef DIRECTED_BROADCAST
251: ia->ia_ifp == m->m_pkthdr.rcvif &&
252: #endif
253: (ia->ia_ifp->if_flags & IFF_BROADCAST)) {
254: u_long t;
255:
256: if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
257: ip->ip_dst.s_addr)
258: goto ours;
259: if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr)
260: goto ours;
261: /*
262: * Look for all-0's host part (old broadcast addr),
263: * either for subnet or net.
264: */
265: t = ntohl(ip->ip_dst.s_addr);
266: if (t == ia->ia_subnet)
267: goto ours;
268: if (t == ia->ia_net)
269: goto ours;
270: }
271: }
272: if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
273: goto ours;
274: if (ip->ip_dst.s_addr == INADDR_ANY)
275: goto ours;
276:
277: /*
278: * Not for us; forward if possible and desirable.
279: */
280: if (ipforwarding == 0) {
281: ipstat.ips_cantforward++;
282: m_freem(m);
283: } else
284: ip_forward(m, 0);
285: goto next;
286:
287: ours:
288: /*
289: * If offset or IP_MF are set, must reassemble.
290: * Otherwise, nothing need be done.
291: * (We could look in the reassembly queue to see
292: * if the packet was previously fragmented,
293: * but it's not worth the time; just let them time out.)
294: */
295: if (ip->ip_off &~ IP_DF) {
296: if (m->m_flags & M_EXT) { /* XXX */
297: if ((m = m_pullup(m, sizeof (struct ip))) == 0) {
298: ipstat.ips_toosmall++;
299: goto next;
300: }
301: ip = mtod(m, struct ip *);
302: }
303: /*
304: * Look for queue of fragments
305: * of this datagram.
306: */
307: for (fp = ipq.next; fp != &ipq; fp = fp->next)
308: if (ip->ip_id == fp->ipq_id &&
309: ip->ip_src.s_addr == fp->ipq_src.s_addr &&
310: ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
311: ip->ip_p == fp->ipq_p)
312: goto found;
313: fp = 0;
314: found:
315:
316: /*
317: * Adjust ip_len to not reflect header,
318: * set ip_mff if more fragments are expected,
319: * convert offset of this to bytes.
320: */
321: ip->ip_len -= hlen;
322: ((struct ipasfrag *)ip)->ipf_mff = 0;
323: if (ip->ip_off & IP_MF)
324: ((struct ipasfrag *)ip)->ipf_mff = 1;
325: ip->ip_off <<= 3;
326:
327: /*
328: * If datagram marked as having more fragments
329: * or if this is not the first fragment,
330: * attempt reassembly; if it succeeds, proceed.
331: */
332: if (((struct ipasfrag *)ip)->ipf_mff || ip->ip_off) {
333: ipstat.ips_fragments++;
334: ip = ip_reass((struct ipasfrag *)ip, fp);
335: if (ip == 0)
336: goto next;
337: else
338: ipstat.ips_reassembled++;
339: m = dtom(ip);
340: } else
341: if (fp)
342: ip_freef(fp);
343: } else
344: ip->ip_len -= hlen;
345:
346: /*
347: * Switch out to protocol's input routine.
348: */
349: ipstat.ips_delivered++;
350: (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
351: goto next;
352: bad:
353: m_freem(m);
354: goto next;
355: }
356:
357: /*
358: * Take incoming datagram fragment and try to
359: * reassemble it into whole datagram. If a chain for
360: * reassembly of this datagram already exists, then it
361: * is given as fp; otherwise have to make a chain.
362: */
363: struct ip *
364: ip_reass(ip, fp)
365: register struct ipasfrag *ip;
366: register struct ipq *fp;
367: {
368: register struct mbuf *m = dtom(ip);
369: register struct ipasfrag *q;
370: struct mbuf *t;
371: int hlen = ip->ip_hl << 2;
372: int i, next;
373:
374: /*
375: * Presence of header sizes in mbufs
376: * would confuse code below.
377: */
378: m->m_data += hlen;
379: m->m_len -= hlen;
380:
381: /*
382: * If first fragment to arrive, create a reassembly queue.
383: */
384: if (fp == 0) {
385: if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
386: goto dropfrag;
387: fp = mtod(t, struct ipq *);
388: insque(fp, &ipq);
389: fp->ipq_ttl = IPFRAGTTL;
390: fp->ipq_p = ip->ip_p;
391: fp->ipq_id = ip->ip_id;
392: fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp;
393: fp->ipq_src = ((struct ip *)ip)->ip_src;
394: fp->ipq_dst = ((struct ip *)ip)->ip_dst;
395: q = (struct ipasfrag *)fp;
396: goto insert;
397: }
398:
399: /*
400: * Find a segment which begins after this one does.
401: */
402: for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next)
403: if (q->ip_off > ip->ip_off)
404: break;
405:
406: /*
407: * If there is a preceding segment, it may provide some of
408: * our data already. If so, drop the data from the incoming
409: * segment. If it provides all of our data, drop us.
410: */
411: if (q->ipf_prev != (struct ipasfrag *)fp) {
412: i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off;
413: if (i > 0) {
414: if (i >= ip->ip_len)
415: goto dropfrag;
416: m_adj(dtom(ip), i);
417: ip->ip_off += i;
418: ip->ip_len -= i;
419: }
420: }
421:
422: /*
423: * While we overlap succeeding segments trim them or,
424: * if they are completely covered, dequeue them.
425: */
426: while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) {
427: i = (ip->ip_off + ip->ip_len) - q->ip_off;
428: if (i < q->ip_len) {
429: q->ip_len -= i;
430: q->ip_off += i;
431: m_adj(dtom(q), i);
432: break;
433: }
434: q = q->ipf_next;
435: m_freem(dtom(q->ipf_prev));
436: ip_deq(q->ipf_prev);
437: }
438:
439: insert:
440: /*
441: * Stick new segment in its place;
442: * check for complete reassembly.
443: */
444: ip_enq(ip, q->ipf_prev);
445: next = 0;
446: for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) {
447: if (q->ip_off != next)
448: return (0);
449: next += q->ip_len;
450: }
451: if (q->ipf_prev->ipf_mff)
452: return (0);
453:
454: /*
455: * Reassembly is complete; concatenate fragments.
456: */
457: q = fp->ipq_next;
458: m = dtom(q);
459: t = m->m_next;
460: m->m_next = 0;
461: m_cat(m, t);
462: q = q->ipf_next;
463: while (q != (struct ipasfrag *)fp) {
464: t = dtom(q);
465: q = q->ipf_next;
466: m_cat(m, t);
467: }
468:
469: /*
470: * Create header for new ip packet by
471: * modifying header of first packet;
472: * dequeue and discard fragment reassembly header.
473: * Make header visible.
474: */
475: ip = fp->ipq_next;
476: ip->ip_len = next;
477: ((struct ip *)ip)->ip_src = fp->ipq_src;
478: ((struct ip *)ip)->ip_dst = fp->ipq_dst;
479: remque(fp);
480: (void) m_free(dtom(fp));
481: m = dtom(ip);
482: m->m_len += (ip->ip_hl << 2);
483: m->m_data -= (ip->ip_hl << 2);
484: /* some debugging cruft by sklower, below, will go away soon */
485: if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
486: register int plen = 0;
487: for (t = m; m; m = m->m_next)
488: plen += m->m_len;
489: t->m_pkthdr.len = plen;
490: }
491: return ((struct ip *)ip);
492:
493: dropfrag:
494: ipstat.ips_fragdropped++;
495: m_freem(m);
496: return (0);
497: }
498:
499: /*
500: * Free a fragment reassembly header and all
501: * associated datagrams.
502: */
503: ip_freef(fp)
504: struct ipq *fp;
505: {
506: register struct ipasfrag *q, *p;
507:
508: for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) {
509: p = q->ipf_next;
510: ip_deq(q);
511: m_freem(dtom(q));
512: }
513: remque(fp);
514: (void) m_free(dtom(fp));
515: }
516:
517: /*
518: * Put an ip fragment on a reassembly chain.
519: * Like insque, but pointers in middle of structure.
520: */
521: ip_enq(p, prev)
522: register struct ipasfrag *p, *prev;
523: {
524:
525: p->ipf_prev = prev;
526: p->ipf_next = prev->ipf_next;
527: prev->ipf_next->ipf_prev = p;
528: prev->ipf_next = p;
529: }
530:
531: /*
532: * To ip_enq as remque is to insque.
533: */
534: ip_deq(p)
535: register struct ipasfrag *p;
536: {
537:
538: p->ipf_prev->ipf_next = p->ipf_next;
539: p->ipf_next->ipf_prev = p->ipf_prev;
540: }
541:
542: /*
543: * IP timer processing;
544: * if a timer expires on a reassembly
545: * queue, discard it.
546: */
547: ip_slowtimo()
548: {
549: register struct ipq *fp;
550: int s = splnet();
551:
552: fp = ipq.next;
553: if (fp == 0) {
554: splx(s);
555: return;
556: }
557: while (fp != &ipq) {
558: --fp->ipq_ttl;
559: fp = fp->next;
560: if (fp->prev->ipq_ttl == 0) {
561: ipstat.ips_fragtimeout++;
562: ip_freef(fp->prev);
563: }
564: }
565: splx(s);
566: }
567:
568: /*
569: * Drain off all datagram fragments.
570: */
571: ip_drain()
572: {
573:
574: while (ipq.next != &ipq) {
575: ipstat.ips_fragdropped++;
576: ip_freef(ipq.next);
577: }
578: }
579:
580: extern struct in_ifaddr *ifptoia();
581: struct in_ifaddr *ip_rtaddr();
582:
583: /*
584: * Do option processing on a datagram,
585: * possibly discarding it if bad options are encountered,
586: * or forwarding it if source-routed.
587: * Returns 1 if packet has been forwarded/freed,
588: * 0 if the packet should be processed further.
589: */
590: ip_dooptions(m)
591: struct mbuf *m;
592: {
593: register struct ip *ip = mtod(m, struct ip *);
594: register u_char *cp;
595: register struct ip_timestamp *ipt;
596: register struct in_ifaddr *ia;
597: int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
598: struct in_addr *sin;
599: n_time ntime;
600:
601: cp = (u_char *)(ip + 1);
602: cnt = (ip->ip_hl << 2) - sizeof (struct ip);
603: for (; cnt > 0; cnt -= optlen, cp += optlen) {
604: opt = cp[IPOPT_OPTVAL];
605: if (opt == IPOPT_EOL)
606: break;
607: if (opt == IPOPT_NOP)
608: optlen = 1;
609: else {
610: optlen = cp[IPOPT_OLEN];
611: if (optlen <= 0 || optlen > cnt) {
612: code = &cp[IPOPT_OLEN] - (u_char *)ip;
613: goto bad;
614: }
615: }
616: switch (opt) {
617:
618: default:
619: break;
620:
621: /*
622: * Source routing with record.
623: * Find interface with current destination address.
624: * If none on this machine then drop if strictly routed,
625: * or do nothing if loosely routed.
626: * Record interface address and bring up next address
627: * component. If strictly routed make sure next
628: * address is on directly accessible net.
629: */
630: case IPOPT_LSRR:
631: case IPOPT_SSRR:
632: if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
633: code = &cp[IPOPT_OFFSET] - (u_char *)ip;
634: goto bad;
635: }
636: ipaddr.sin_addr = ip->ip_dst;
637: ia = (struct in_ifaddr *)
638: ifa_ifwithaddr((struct sockaddr *)&ipaddr);
639: if (ia == 0) {
640: if (opt == IPOPT_SSRR) {
641: type = ICMP_UNREACH;
642: code = ICMP_UNREACH_SRCFAIL;
643: goto bad;
644: }
645: /*
646: * Loose routing, and not at next destination
647: * yet; nothing to do except forward.
648: */
649: break;
650: }
651: off--; /* 0 origin */
652: if (off > optlen - sizeof(struct in_addr)) {
653: /*
654: * End of source route. Should be for us.
655: */
656: save_rte(cp, ip->ip_src);
657: break;
658: }
659: /*
660: * locate outgoing interface
661: */
662: bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
663: sizeof(ipaddr.sin_addr));
664: if (opt == IPOPT_SSRR) {
665: #define INA struct in_ifaddr *
666: #define SA struct sockaddr *
667: if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
668: ia = in_iaonnetof(in_netof(ipaddr.sin_addr));
669: } else
670: ia = ip_rtaddr(ipaddr.sin_addr);
671: if (ia == 0) {
672: type = ICMP_UNREACH;
673: code = ICMP_UNREACH_SRCFAIL;
674: goto bad;
675: }
676: ip->ip_dst = ipaddr.sin_addr;
677: bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
678: (caddr_t)(cp + off), sizeof(struct in_addr));
679: cp[IPOPT_OFFSET] += sizeof(struct in_addr);
680: forward = 1;
681: break;
682:
683: case IPOPT_RR:
684: if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
685: code = &cp[IPOPT_OFFSET] - (u_char *)ip;
686: goto bad;
687: }
688: /*
689: * If no space remains, ignore.
690: */
691: off--; /* 0 origin */
692: if (off > optlen - sizeof(struct in_addr))
693: break;
694: bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
695: sizeof(ipaddr.sin_addr));
696: /*
697: * locate outgoing interface; if we're the destination,
698: * use the incoming interface (should be same).
699: */
700: if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
701: (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
702: type = ICMP_UNREACH;
703: code = ICMP_UNREACH_HOST;
704: goto bad;
705: }
706: bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
707: (caddr_t)(cp + off), sizeof(struct in_addr));
708: cp[IPOPT_OFFSET] += sizeof(struct in_addr);
709: break;
710:
711: case IPOPT_TS:
712: code = cp - (u_char *)ip;
713: ipt = (struct ip_timestamp *)cp;
714: if (ipt->ipt_len < 5)
715: goto bad;
716: if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) {
717: if (++ipt->ipt_oflw == 0)
718: goto bad;
719: break;
720: }
721: sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
722: switch (ipt->ipt_flg) {
723:
724: case IPOPT_TS_TSONLY:
725: break;
726:
727: case IPOPT_TS_TSANDADDR:
728: if (ipt->ipt_ptr + sizeof(n_time) +
729: sizeof(struct in_addr) > ipt->ipt_len)
730: goto bad;
731: ia = ifptoia(m->m_pkthdr.rcvif);
732: bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
733: (caddr_t)sin, sizeof(struct in_addr));
734: ipt->ipt_ptr += sizeof(struct in_addr);
735: break;
736:
737: case IPOPT_TS_PRESPEC:
738: if (ipt->ipt_ptr + sizeof(n_time) +
739: sizeof(struct in_addr) > ipt->ipt_len)
740: goto bad;
741: bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
742: sizeof(struct in_addr));
743: if (ifa_ifwithaddr((SA)&ipaddr) == 0)
744: continue;
745: ipt->ipt_ptr += sizeof(struct in_addr);
746: break;
747:
748: default:
749: goto bad;
750: }
751: ntime = iptime();
752: bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
753: sizeof(n_time));
754: ipt->ipt_ptr += sizeof(n_time);
755: }
756: }
757: if (forward) {
758: ip_forward(m, 1);
759: return (1);
760: } else
761: return (0);
762: bad:
763: icmp_error(m, type, code);
764: return (1);
765: }
766:
767: /*
768: * Given address of next destination (final or next hop),
769: * return internet address info of interface to be used to get there.
770: */
771: struct in_ifaddr *
772: ip_rtaddr(dst)
773: struct in_addr dst;
774: {
775: register struct sockaddr_in *sin;
776:
777: sin = (struct sockaddr_in *) &ipforward_rt.ro_dst;
778:
779: if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) {
780: if (ipforward_rt.ro_rt) {
781: RTFREE(ipforward_rt.ro_rt);
782: ipforward_rt.ro_rt = 0;
783: }
784: sin->sin_family = AF_INET;
785: sin->sin_len = sizeof(*sin);
786: sin->sin_addr = dst;
787:
788: rtalloc(&ipforward_rt);
789: }
790: if (ipforward_rt.ro_rt == 0)
791: return ((struct in_ifaddr *)0);
792: return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa);
793: }
794:
795: /*
796: * Save incoming source route for use in replies,
797: * to be picked up later by ip_srcroute if the receiver is interested.
798: */
799: save_rte(option, dst)
800: u_char *option;
801: struct in_addr dst;
802: {
803: unsigned olen;
804:
805: olen = option[IPOPT_OLEN];
806: #ifdef DIAGNOSTIC
807: if (ipprintfs)
808: printf("save_rte: olen %d\n", olen);
809: #endif
810: if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
811: return;
812: bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen);
813: ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
814: ip_srcrt.dst = dst;
815: }
816:
817: /*
818: * Retrieve incoming source route for use in replies,
819: * in the same form used by setsockopt.
820: * The first hop is placed before the options, will be removed later.
821: */
822: struct mbuf *
823: ip_srcroute()
824: {
825: register struct in_addr *p, *q;
826: register struct mbuf *m;
827:
828: if (ip_nhops == 0)
829: return ((struct mbuf *)0);
830: m = m_get(M_DONTWAIT, MT_SOOPTS);
831: if (m == 0)
832: return ((struct mbuf *)0);
833:
834: #define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
835:
836: /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
837: m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
838: OPTSIZ;
839: #ifdef DIAGNOSTIC
840: if (ipprintfs)
841: printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
842: #endif
843:
844: /*
845: * First save first hop for return route
846: */
847: p = &ip_srcrt.route[ip_nhops - 1];
848: *(mtod(m, struct in_addr *)) = *p--;
849: #ifdef DIAGNOSTIC
850: if (ipprintfs)
851: printf(" hops %lx", ntohl(mtod(m, struct in_addr *)->s_addr));
852: #endif
853:
854: /*
855: * Copy option fields and padding (nop) to mbuf.
856: */
857: ip_srcrt.nop = IPOPT_NOP;
858: ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
859: bcopy((caddr_t)&ip_srcrt.nop,
860: mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ);
861: q = (struct in_addr *)(mtod(m, caddr_t) +
862: sizeof(struct in_addr) + OPTSIZ);
863: #undef OPTSIZ
864: /*
865: * Record return path as an IP source route,
866: * reversing the path (pointers are now aligned).
867: */
868: while (p >= ip_srcrt.route) {
869: #ifdef DIAGNOSTIC
870: if (ipprintfs)
871: printf(" %lx", ntohl(q->s_addr));
872: #endif
873: *q++ = *p--;
874: }
875: /*
876: * Last hop goes to final destination.
877: */
878: *q = ip_srcrt.dst;
879: #ifdef DIAGNOSTIC
880: if (ipprintfs)
881: printf(" %lx\n", ntohl(q->s_addr));
882: #endif
883: return (m);
884: }
885:
886: /*
887: * Strip out IP options, at higher
888: * level protocol in the kernel.
889: * Second argument is buffer to which options
890: * will be moved, and return value is their length.
891: * XXX should be deleted; last arg currently ignored.
892: */
893: ip_stripoptions(m, mopt)
894: register struct mbuf *m;
895: struct mbuf *mopt;
896: {
897: register int i;
898: struct ip *ip = mtod(m, struct ip *);
899: register caddr_t opts;
900: int olen;
901:
902: olen = (ip->ip_hl<<2) - sizeof (struct ip);
903: opts = (caddr_t)(ip + 1);
904: i = m->m_len - (sizeof (struct ip) + olen);
905: bcopy(opts + olen, opts, (unsigned)i);
906: m->m_len -= olen;
907: if (m->m_flags & M_PKTHDR)
908: m->m_pkthdr.len -= olen;
909: ip->ip_hl = sizeof(struct ip) >> 2;
910: }
911:
912: u_char inetctlerrmap[PRC_NCMDS] = {
913: 0, 0, 0, 0,
914: 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH,
915: EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED,
916: EMSGSIZE, EHOSTUNREACH, 0, 0,
917: 0, 0, 0, 0,
918: ENOPROTOOPT
919: };
920:
921: /*
922: * Forward a packet. If some error occurs return the sender
923: * an icmp packet. Note we can't always generate a meaningful
924: * icmp message because icmp doesn't have a large enough repertoire
925: * of codes and types.
926: *
927: * If not forwarding, just drop the packet. This could be confusing
928: * if ipforwarding was zero but some routing protocol was advancing
929: * us as a gateway to somewhere. However, we must let the routing
930: * protocol deal with that.
931: *
932: * The srcrt parameter indicates whether the packet is being forwarded
933: * via a source route.
934: */
935: ip_forward(m, srcrt)
936: struct mbuf *m;
937: int srcrt;
938: {
939: register struct ip *ip = mtod(m, struct ip *);
940: register struct sockaddr_in *sin;
941: register struct rtentry *rt;
942: int error, type = 0, code;
943: struct mbuf *mcopy;
944: struct in_addr dest;
945:
946: dest.s_addr = 0;
947: #ifdef DIAGNOSTIC
948: if (ipprintfs)
949: printf("forward: src %x dst %x ttl %x\n", ip->ip_src,
950: ip->ip_dst, ip->ip_ttl);
951: #endif
952: if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) {
953: ipstat.ips_cantforward++;
954: m_freem(m);
955: return;
956: }
957: HTONS(ip->ip_id);
958: if (ip->ip_ttl <= IPTTLDEC) {
959: icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest);
960: return;
961: }
962: ip->ip_ttl -= IPTTLDEC;
963:
964: sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
965: if ((rt = ipforward_rt.ro_rt) == 0 ||
966: ip->ip_dst.s_addr != sin->sin_addr.s_addr) {
967: if (ipforward_rt.ro_rt) {
968: RTFREE(ipforward_rt.ro_rt);
969: ipforward_rt.ro_rt = 0;
970: }
971: sin->sin_family = AF_INET;
972: sin->sin_len = sizeof(*sin);
973: sin->sin_addr = ip->ip_dst;
974:
975: rtalloc(&ipforward_rt);
976: if (ipforward_rt.ro_rt == 0) {
977: icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest);
978: return;
979: }
980: rt = ipforward_rt.ro_rt;
981: }
982:
983: /*
984: * Save at most 64 bytes of the packet in case
985: * we need to generate an ICMP message to the src.
986: */
987: mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64));
988:
989: #ifdef GATEWAY
990: ip_ifmatrix[rt->rt_ifp->if_index +
991: if_index * m->m_pkthdr.rcvif->if_index]++;
992: #endif
993: /*
994: * If forwarding packet using same interface that it came in on,
995: * perhaps should send a redirect to sender to shortcut a hop.
996: * Only send redirect if source is sending directly to us,
997: * and if packet was not source routed (or has any options).
998: * Also, don't send redirect if forwarding using a default route
999: * or a route modified by a redirect.
1000: */
1001: #define satosin(sa) ((struct sockaddr_in *)(sa))
1002: if (rt->rt_ifp == m->m_pkthdr.rcvif &&
1003: (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1004: satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
1005: ipsendredirects && !srcrt) {
1006: struct in_ifaddr *ia;
1007: u_long src = ntohl(ip->ip_src.s_addr);
1008: u_long dst = ntohl(ip->ip_dst.s_addr);
1009:
1010: if ((ia = ifptoia(m->m_pkthdr.rcvif)) &&
1011: (src & ia->ia_subnetmask) == ia->ia_subnet) {
1012: if (rt->rt_flags & RTF_GATEWAY)
1013: dest = satosin(rt->rt_gateway)->sin_addr;
1014: else
1015: dest = ip->ip_dst;
1016: /*
1017: * If the destination is reached by a route to host,
1018: * is on a subnet of a local net, or is directly
1019: * on the attached net (!), use host redirect.
1020: * (We may be the correct first hop for other subnets.)
1021: */
1022: #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa))
1023: type = ICMP_REDIRECT;
1024: if ((rt->rt_flags & RTF_HOST) ||
1025: (rt->rt_flags & RTF_GATEWAY) == 0)
1026: code = ICMP_REDIRECT_HOST;
1027: else if (RTA(rt)->ia_subnetmask != RTA(rt)->ia_netmask &&
1028: (dst & RTA(rt)->ia_netmask) == RTA(rt)->ia_net)
1029: code = ICMP_REDIRECT_HOST;
1030: else
1031: code = ICMP_REDIRECT_NET;
1032: #ifdef DIAGNOSTIC
1033: if (ipprintfs)
1034: printf("redirect (%d) to %x\n", code, dest.s_addr);
1035: #endif
1036: }
1037: }
1038:
1039: error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING);
1040: if (error)
1041: ipstat.ips_cantforward++;
1042: else {
1043: ipstat.ips_forward++;
1044: if (type)
1045: ipstat.ips_redirectsent++;
1046: else {
1047: if (mcopy)
1048: m_freem(mcopy);
1049: return;
1050: }
1051: }
1052: if (mcopy == NULL)
1053: return;
1054: switch (error) {
1055:
1056: case 0: /* forwarded, but need redirect */
1057: /* type, code set above */
1058: break;
1059:
1060: case ENETUNREACH: /* shouldn't happen, checked above */
1061: case EHOSTUNREACH:
1062: case ENETDOWN:
1063: case EHOSTDOWN:
1064: default:
1065: type = ICMP_UNREACH;
1066: code = ICMP_UNREACH_HOST;
1067: break;
1068:
1069: case EMSGSIZE:
1070: type = ICMP_UNREACH;
1071: code = ICMP_UNREACH_NEEDFRAG;
1072: ipstat.ips_cantfrag++;
1073: break;
1074:
1075: case ENOBUFS:
1076: type = ICMP_SOURCEQUENCH;
1077: code = 0;
1078: break;
1079: }
1080: icmp_error(mcopy, type, code, dest);
1081: }
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