FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_icmp.c
1 /*
2 * Copyright (c) 1982, 1986, 1988, 1993
3 * The Regents of the University of California. 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_icmp.c 8.2 (Berkeley) 1/4/94
34 * $FreeBSD: src/sys/netinet/ip_icmp.c,v 1.22.2.6 2000/06/26 20:49:21 alfred Exp $
35 */
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/malloc.h>
40 #include <sys/mbuf.h>
41 #include <sys/protosw.h>
42 #include <sys/socket.h>
43 #include <sys/time.h>
44 #include <sys/kernel.h>
45 #include <sys/socket.h>
46 #include <sys/sysctl.h>
47
48 #include <net/if.h>
49 #include <net/route.h>
50
51 #define _IP_VHL
52 #include <netinet/in.h>
53 #include <netinet/in_systm.h>
54 #include <netinet/in_var.h>
55 #include <netinet/ip.h>
56 #include <netinet/ip_icmp.h>
57 #include <netinet/ip_var.h>
58 #include <netinet/icmp_var.h>
59
60 /*
61 * ICMP routines: error generation, receive packet processing, and
62 * routines to turnaround packets back to the originator, and
63 * host table maintenance routines.
64 */
65
66 static struct icmpstat icmpstat;
67 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RD,
68 &icmpstat, icmpstat, "");
69
70 static int icmpmaskrepl = 0;
71 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
72 &icmpmaskrepl, 0, "");
73
74 static int icmpbmcastecho = 1;
75 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, &icmpbmcastecho,
76 0, "");
77
78 #ifdef ICMPPRINTFS
79 int icmpprintfs = 0;
80 #endif
81
82 static void icmp_reflect __P((struct mbuf *));
83 static void icmp_send __P((struct mbuf *, struct mbuf *));
84 static int ip_next_mtu __P((int, int));
85
86 extern struct protosw inetsw[];
87
88 /*
89 * Generate an error packet of type error
90 * in response to bad packet ip.
91 */
92 void
93 icmp_error(n, type, code, dest, destifp)
94 struct mbuf *n;
95 int type, code;
96 n_long dest;
97 struct ifnet *destifp;
98 {
99 register struct ip *oip = mtod(n, struct ip *), *nip;
100 register unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
101 register struct icmp *icp;
102 register struct mbuf *m;
103 unsigned icmplen;
104
105 #ifdef ICMPPRINTFS
106 if (icmpprintfs)
107 printf("icmp_error(%p, %x, %d)\n", oip, type, code);
108 #endif
109 if (type != ICMP_REDIRECT)
110 icmpstat.icps_error++;
111 /*
112 * Don't send error if not the first fragment of message.
113 * Don't error if the old packet protocol was ICMP
114 * error message, only known informational types.
115 */
116 if (oip->ip_off &~ (IP_MF|IP_DF))
117 goto freeit;
118 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
119 n->m_len >= oiplen + ICMP_MINLEN &&
120 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) {
121 icmpstat.icps_oldicmp++;
122 goto freeit;
123 }
124 /* Don't send error in response to a multicast or broadcast packet */
125 if (n->m_flags & (M_BCAST|M_MCAST))
126 goto freeit;
127 /*
128 * First, formulate icmp message
129 */
130 m = m_gethdr(M_DONTWAIT, MT_HEADER);
131 if (m == NULL)
132 goto freeit;
133 icmplen = oiplen + min(8, oip->ip_len);
134 m->m_len = icmplen + ICMP_MINLEN;
135 MH_ALIGN(m, m->m_len);
136 icp = mtod(m, struct icmp *);
137 if ((u_int)type > ICMP_MAXTYPE)
138 panic("icmp_error");
139 icmpstat.icps_outhist[type]++;
140 icp->icmp_type = type;
141 if (type == ICMP_REDIRECT)
142 icp->icmp_gwaddr.s_addr = dest;
143 else {
144 icp->icmp_void = 0;
145 /*
146 * The following assignments assume an overlay with the
147 * zeroed icmp_void field.
148 */
149 if (type == ICMP_PARAMPROB) {
150 icp->icmp_pptr = code;
151 code = 0;
152 } else if (type == ICMP_UNREACH &&
153 code == ICMP_UNREACH_NEEDFRAG && destifp) {
154 icp->icmp_nextmtu = htons(destifp->if_mtu);
155 }
156 }
157
158 icp->icmp_code = code;
159 bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen);
160 nip = &icp->icmp_ip;
161 nip->ip_len = htons((u_short)(nip->ip_len + oiplen));
162
163 /*
164 * Now, copy old ip header (without options)
165 * in front of icmp message.
166 */
167 if (m->m_data - sizeof(struct ip) < m->m_pktdat)
168 panic("icmp len");
169 m->m_data -= sizeof(struct ip);
170 m->m_len += sizeof(struct ip);
171 m->m_pkthdr.len = m->m_len;
172 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
173 nip = mtod(m, struct ip *);
174 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
175 nip->ip_len = m->m_len;
176 nip->ip_vhl = IP_VHL_BORING;
177 nip->ip_p = IPPROTO_ICMP;
178 nip->ip_tos = 0;
179 icmp_reflect(m);
180
181 freeit:
182 m_freem(n);
183 }
184
185 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
186 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
187 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
188
189 /*
190 * Process a received ICMP message.
191 */
192 void
193 icmp_input(m, hlen)
194 register struct mbuf *m;
195 int hlen;
196 {
197 register struct icmp *icp;
198 register struct ip *ip = mtod(m, struct ip *);
199 int icmplen = ip->ip_len;
200 register int i;
201 struct in_ifaddr *ia;
202 void (*ctlfunc) __P((int, struct sockaddr *, void *));
203 int code;
204
205 /*
206 * Locate icmp structure in mbuf, and check
207 * that not corrupted and of at least minimum length.
208 */
209 #ifdef ICMPPRINTFS
210 if (icmpprintfs) {
211 char buf[4 * sizeof "123"];
212 strcpy(buf, inet_ntoa(ip->ip_src));
213 printf("icmp_input from %s to %s, len %d\n",
214 buf, inet_ntoa(ip->ip_dst), icmplen);
215 }
216 #endif
217 if (icmplen < ICMP_MINLEN) {
218 icmpstat.icps_tooshort++;
219 goto freeit;
220 }
221 i = hlen + min(icmplen, ICMP_ADVLENMIN);
222 if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
223 icmpstat.icps_tooshort++;
224 return;
225 }
226 ip = mtod(m, struct ip *);
227 m->m_len -= hlen;
228 m->m_data += hlen;
229 icp = mtod(m, struct icmp *);
230 if (in_cksum(m, icmplen)) {
231 icmpstat.icps_checksum++;
232 goto freeit;
233 }
234 m->m_len += hlen;
235 m->m_data -= hlen;
236
237 #ifdef ICMPPRINTFS
238 if (icmpprintfs)
239 printf("icmp_input, type %d code %d\n", icp->icmp_type,
240 icp->icmp_code);
241 #endif
242
243 /*
244 * Message type specific processing.
245 */
246 if (icp->icmp_type > ICMP_MAXTYPE)
247 goto raw;
248 icmpstat.icps_inhist[icp->icmp_type]++;
249 code = icp->icmp_code;
250 switch (icp->icmp_type) {
251
252 case ICMP_UNREACH:
253 switch (code) {
254 case ICMP_UNREACH_NET:
255 case ICMP_UNREACH_HOST:
256 case ICMP_UNREACH_PROTOCOL:
257 case ICMP_UNREACH_PORT:
258 case ICMP_UNREACH_SRCFAIL:
259 code += PRC_UNREACH_NET;
260 break;
261
262 case ICMP_UNREACH_NEEDFRAG:
263 code = PRC_MSGSIZE;
264 break;
265
266 case ICMP_UNREACH_NET_UNKNOWN:
267 case ICMP_UNREACH_NET_PROHIB:
268 case ICMP_UNREACH_TOSNET:
269 code = PRC_UNREACH_NET;
270 break;
271
272 case ICMP_UNREACH_HOST_UNKNOWN:
273 case ICMP_UNREACH_ISOLATED:
274 case ICMP_UNREACH_HOST_PROHIB:
275 case ICMP_UNREACH_TOSHOST:
276 code = PRC_UNREACH_HOST;
277 break;
278
279 case ICMP_UNREACH_FILTER_PROHIB:
280 case ICMP_UNREACH_HOST_PRECEDENCE:
281 case ICMP_UNREACH_PRECEDENCE_CUTOFF:
282 code = PRC_UNREACH_PORT;
283 break;
284
285 default:
286 goto badcode;
287 }
288 goto deliver;
289
290 case ICMP_TIMXCEED:
291 if (code > 1)
292 goto badcode;
293 code += PRC_TIMXCEED_INTRANS;
294 goto deliver;
295
296 case ICMP_PARAMPROB:
297 if (code > 1)
298 goto badcode;
299 code = PRC_PARAMPROB;
300 goto deliver;
301
302 case ICMP_SOURCEQUENCH:
303 if (code)
304 goto badcode;
305 code = PRC_QUENCH;
306 deliver:
307 /*
308 * Problem with datagram; advise higher level routines.
309 */
310 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
311 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
312 icmpstat.icps_badlen++;
313 goto freeit;
314 }
315 NTOHS(icp->icmp_ip.ip_len);
316 /* Discard ICMP's in response to multicast packets */
317 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
318 goto badcode;
319 #ifdef ICMPPRINTFS
320 if (icmpprintfs)
321 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
322 #endif
323 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
324 #if 1
325 /*
326 * MTU discovery:
327 * If we got a needfrag and there is a host route to the
328 * original destination, and the MTU is not locked, then
329 * set the MTU in the route to the suggested new value
330 * (if given) and then notify as usual. The ULPs will
331 * notice that the MTU has changed and adapt accordingly.
332 * If no new MTU was suggested, then we guess a new one
333 * less than the current value. If the new MTU is
334 * unreasonably small (arbitrarily set at 296), then
335 * we reset the MTU to the interface value and enable the
336 * lock bit, indicating that we are no longer doing MTU
337 * discovery.
338 */
339 if (code == PRC_MSGSIZE) {
340 struct rtentry *rt;
341 int mtu;
342
343 rt = rtalloc1((struct sockaddr *)&icmpsrc, 0,
344 RTF_CLONING | RTF_PRCLONING);
345 if (rt && (rt->rt_flags & RTF_HOST)
346 && !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
347 mtu = ntohs(icp->icmp_nextmtu);
348 if (!mtu)
349 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
350 1);
351 #ifdef DEBUG_MTUDISC
352 printf("MTU for %s reduced to %d\n",
353 inet_ntoa(icmpsrc.sin_addr), mtu);
354 #endif
355 if (mtu < 296) {
356 /* rt->rt_rmx.rmx_mtu =
357 rt->rt_ifp->if_mtu; */
358 rt->rt_rmx.rmx_locks |= RTV_MTU;
359 } else if (rt->rt_rmx.rmx_mtu > mtu) {
360 rt->rt_rmx.rmx_mtu = mtu;
361 }
362 }
363 if (rt)
364 RTFREE(rt);
365 }
366
367 #endif
368 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
369 if (ctlfunc)
370 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
371 (void *)&icp->icmp_ip);
372 break;
373
374 badcode:
375 icmpstat.icps_badcode++;
376 break;
377
378 case ICMP_ECHO:
379 if (!icmpbmcastecho
380 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
381 icmpstat.icps_bmcastecho++;
382 break;
383 }
384 icp->icmp_type = ICMP_ECHOREPLY;
385 goto reflect;
386
387 case ICMP_TSTAMP:
388 if (!icmpbmcastecho
389 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
390 icmpstat.icps_bmcasttstamp++;
391 break;
392 }
393 if (icmplen < ICMP_TSLEN) {
394 icmpstat.icps_badlen++;
395 break;
396 }
397 icp->icmp_type = ICMP_TSTAMPREPLY;
398 icp->icmp_rtime = iptime();
399 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
400 goto reflect;
401
402 case ICMP_MASKREQ:
403 #define satosin(sa) ((struct sockaddr_in *)(sa))
404 if (icmpmaskrepl == 0)
405 break;
406 /*
407 * We are not able to respond with all ones broadcast
408 * unless we receive it over a point-to-point interface.
409 */
410 if (icmplen < ICMP_MASKLEN)
411 break;
412 switch (ip->ip_dst.s_addr) {
413
414 case INADDR_BROADCAST:
415 case INADDR_ANY:
416 icmpdst.sin_addr = ip->ip_src;
417 break;
418
419 default:
420 icmpdst.sin_addr = ip->ip_dst;
421 }
422 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
423 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
424 if (ia == 0)
425 break;
426 if (ia->ia_ifp == 0)
427 break;
428 icp->icmp_type = ICMP_MASKREPLY;
429 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
430 if (ip->ip_src.s_addr == 0) {
431 if (ia->ia_ifp->if_flags & IFF_BROADCAST)
432 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
433 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
434 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
435 }
436 reflect:
437 ip->ip_len += hlen; /* since ip_input deducts this */
438 icmpstat.icps_reflect++;
439 icmpstat.icps_outhist[icp->icmp_type]++;
440 icmp_reflect(m);
441 return;
442
443 case ICMP_REDIRECT:
444 if (code > 3)
445 goto badcode;
446 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
447 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
448 icmpstat.icps_badlen++;
449 break;
450 }
451 /*
452 * Short circuit routing redirects to force
453 * immediate change in the kernel's routing
454 * tables. The message is also handed to anyone
455 * listening on a raw socket (e.g. the routing
456 * daemon for use in updating its tables).
457 */
458 icmpgw.sin_addr = ip->ip_src;
459 icmpdst.sin_addr = icp->icmp_gwaddr;
460 #ifdef ICMPPRINTFS
461 if (icmpprintfs) {
462 char buf[4 * sizeof "123"];
463 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
464
465 printf("redirect dst %s to %s\n",
466 buf, inet_ntoa(icp->icmp_gwaddr));
467 }
468 #endif
469 icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
470 rtredirect((struct sockaddr *)&icmpsrc,
471 (struct sockaddr *)&icmpdst,
472 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
473 (struct sockaddr *)&icmpgw, (struct rtentry **)0);
474 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
475 break;
476
477 /*
478 * No kernel processing for the following;
479 * just fall through to send to raw listener.
480 */
481 case ICMP_ECHOREPLY:
482 case ICMP_ROUTERADVERT:
483 case ICMP_ROUTERSOLICIT:
484 case ICMP_TSTAMPREPLY:
485 case ICMP_IREQREPLY:
486 case ICMP_MASKREPLY:
487 default:
488 break;
489 }
490
491 raw:
492 rip_input(m, hlen);
493 return;
494
495 freeit:
496 m_freem(m);
497 }
498
499 /*
500 * Reflect the ip packet back to the source
501 */
502 static void
503 icmp_reflect(m)
504 struct mbuf *m;
505 {
506 register struct ip *ip = mtod(m, struct ip *);
507 register struct in_ifaddr *ia;
508 struct in_addr t;
509 struct mbuf *opts = 0;
510 int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
511
512 if (!in_canforward(ip->ip_src) &&
513 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
514 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
515 m_freem(m); /* Bad return address */
516 goto done; /* Ip_output() will check for broadcast */
517 }
518 t = ip->ip_dst;
519 ip->ip_dst = ip->ip_src;
520 /*
521 * If the incoming packet was addressed directly to us,
522 * use dst as the src for the reply. Otherwise (broadcast
523 * or anonymous), use the address which corresponds
524 * to the incoming interface.
525 */
526 for (ia = in_ifaddr; ia; ia = ia->ia_next) {
527 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
528 break;
529 if (ia->ia_ifp && (ia->ia_ifp->if_flags & IFF_BROADCAST) &&
530 t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr)
531 break;
532 }
533 icmpdst.sin_addr = t;
534 if ((ia == (struct in_ifaddr *)0) && m->m_pkthdr.rcvif)
535 ia = (struct in_ifaddr *)ifaof_ifpforaddr(
536 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
537 /*
538 * The following happens if the packet was not addressed to us,
539 * and was received on an interface with no IP address.
540 */
541 if (ia == (struct in_ifaddr *)0)
542 ia = in_ifaddr;
543 t = IA_SIN(ia)->sin_addr;
544 ip->ip_src = t;
545 ip->ip_ttl = MAXTTL;
546
547 if (optlen > 0) {
548 register u_char *cp;
549 int opt, cnt;
550 u_int len;
551
552 /*
553 * Retrieve any source routing from the incoming packet;
554 * add on any record-route or timestamp options.
555 */
556 cp = (u_char *) (ip + 1);
557 if ((opts = ip_srcroute()) == 0 &&
558 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
559 opts->m_len = sizeof(struct in_addr);
560 mtod(opts, struct in_addr *)->s_addr = 0;
561 }
562 if (opts) {
563 #ifdef ICMPPRINTFS
564 if (icmpprintfs)
565 printf("icmp_reflect optlen %d rt %d => ",
566 optlen, opts->m_len);
567 #endif
568 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
569 opt = cp[IPOPT_OPTVAL];
570 if (opt == IPOPT_EOL)
571 break;
572 if (opt == IPOPT_NOP)
573 len = 1;
574 else {
575 if (cnt < IPOPT_OLEN + sizeof(*cp))
576 break;
577 len = cp[IPOPT_OLEN];
578 if (len < IPOPT_OLEN + sizeof(*cp) ||
579 len > cnt)
580 break;
581 }
582 /*
583 * Should check for overflow, but it "can't happen"
584 */
585 if (opt == IPOPT_RR || opt == IPOPT_TS ||
586 opt == IPOPT_SECURITY) {
587 bcopy((caddr_t)cp,
588 mtod(opts, caddr_t) + opts->m_len, len);
589 opts->m_len += len;
590 }
591 }
592 /* Terminate & pad, if necessary */
593 cnt = opts->m_len % 4;
594 if (cnt) {
595 for (; cnt < 4; cnt++) {
596 *(mtod(opts, caddr_t) + opts->m_len) =
597 IPOPT_EOL;
598 opts->m_len++;
599 }
600 }
601 #ifdef ICMPPRINTFS
602 if (icmpprintfs)
603 printf("%d\n", opts->m_len);
604 #endif
605 }
606 /*
607 * Now strip out original options by copying rest of first
608 * mbuf's data back, and adjust the IP length.
609 */
610 ip->ip_len -= optlen;
611 ip->ip_vhl = IP_VHL_BORING;
612 m->m_len -= optlen;
613 if (m->m_flags & M_PKTHDR)
614 m->m_pkthdr.len -= optlen;
615 optlen += sizeof(struct ip);
616 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
617 (unsigned)(m->m_len - sizeof(struct ip)));
618 }
619 m->m_flags &= ~(M_BCAST|M_MCAST);
620 icmp_send(m, opts);
621 done:
622 if (opts)
623 (void)m_free(opts);
624 }
625
626 /*
627 * Send an icmp packet back to the ip level,
628 * after supplying a checksum.
629 */
630 static void
631 icmp_send(m, opts)
632 register struct mbuf *m;
633 struct mbuf *opts;
634 {
635 register struct ip *ip = mtod(m, struct ip *);
636 register int hlen;
637 register struct icmp *icp;
638 struct route ro;
639
640 hlen = IP_VHL_HL(ip->ip_vhl) << 2;
641 m->m_data += hlen;
642 m->m_len -= hlen;
643 icp = mtod(m, struct icmp *);
644 icp->icmp_cksum = 0;
645 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
646 m->m_data -= hlen;
647 m->m_len += hlen;
648 m->m_pkthdr.rcvif = (struct ifnet *)0;
649 #ifdef ICMPPRINTFS
650 if (icmpprintfs) {
651 char buf[4 * sizeof "123"];
652 strcpy(buf, inet_ntoa(ip->ip_dst));
653 printf("icmp_send dst %s src %s\n",
654 buf, inet_ntoa(ip->ip_src));
655 }
656 #endif
657 bzero(&ro, sizeof ro);
658 (void) ip_output(m, opts, &ro, 0, NULL);
659 if (ro.ro_rt)
660 RTFREE(ro.ro_rt);
661 }
662
663 n_time
664 iptime()
665 {
666 struct timeval atv;
667 u_long t;
668
669 microtime(&atv);
670 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
671 return (htonl(t));
672 }
673
674 #if 1
675 /*
676 * Return the next larger or smaller MTU plateau (table from RFC 1191)
677 * given current value MTU. If DIR is less than zero, a larger plateau
678 * is returned; otherwise, a smaller value is returned.
679 */
680 static int
681 ip_next_mtu(mtu, dir)
682 int mtu;
683 int dir;
684 {
685 static int mtutab[] = {
686 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
687 68, 0
688 };
689 int i;
690
691 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
692 if (mtu >= mtutab[i])
693 break;
694 }
695
696 if (dir < 0) {
697 if (i == 0) {
698 return 0;
699 } else {
700 return mtutab[i - 1];
701 }
702 } else {
703 if (mtutab[i] == 0) {
704 return 0;
705 } else if(mtu > mtutab[i]) {
706 return mtutab[i];
707 } else {
708 return mtutab[i + 1];
709 }
710 }
711 }
712 #endif
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