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 * $Id: ip_icmp.c,v 1.9 1995/08/29 17:49:04 wollman 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 <vm/vm.h> 47 #include <sys/sysctl.h> 48 49 #include <net/if.h> 50 #include <net/route.h> 51 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 struct icmpstat icmpstat; 67 int icmpmaskrepl = 0; 68 #ifdef ICMPPRINTFS 69 int icmpprintfs = 0; 70 #endif 71 72 extern struct protosw inetsw[]; 73 74 /* 75 * Generate an error packet of type error 76 * in response to bad packet ip. 77 */ 78 void 79 icmp_error(n, type, code, dest, destifp) 80 struct mbuf *n; 81 int type, code; 82 n_long dest; 83 struct ifnet *destifp; 84 { 85 register struct ip *oip = mtod(n, struct ip *), *nip; 86 register unsigned oiplen = oip->ip_hl << 2; 87 register struct icmp *icp; 88 register struct mbuf *m; 89 unsigned icmplen; 90 91 #ifdef ICMPPRINTFS 92 if (icmpprintfs) 93 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 94 #endif 95 if (type != ICMP_REDIRECT) 96 icmpstat.icps_error++; 97 /* 98 * Don't send error if not the first fragment of message. 99 * Don't error if the old packet protocol was ICMP 100 * error message, only known informational types. 101 */ 102 if (oip->ip_off &~ (IP_MF|IP_DF)) 103 goto freeit; 104 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 105 n->m_len >= oiplen + ICMP_MINLEN && 106 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 107 icmpstat.icps_oldicmp++; 108 goto freeit; 109 } 110 /* Don't send error in response to a multicast or broadcast packet */ 111 if (n->m_flags & (M_BCAST|M_MCAST)) 112 goto freeit; 113 /* 114 * First, formulate icmp message 115 */ 116 m = m_gethdr(M_DONTWAIT, MT_HEADER); 117 if (m == NULL) 118 goto freeit; 119 icmplen = oiplen + min(8, oip->ip_len); 120 m->m_len = icmplen + ICMP_MINLEN; 121 MH_ALIGN(m, m->m_len); 122 icp = mtod(m, struct icmp *); 123 if ((u_int)type > ICMP_MAXTYPE) 124 panic("icmp_error"); 125 icmpstat.icps_outhist[type]++; 126 icp->icmp_type = type; 127 if (type == ICMP_REDIRECT) 128 icp->icmp_gwaddr.s_addr = dest; 129 else { 130 icp->icmp_void = 0; 131 /* 132 * The following assignments assume an overlay with the 133 * zeroed icmp_void field. 134 */ 135 if (type == ICMP_PARAMPROB) { 136 icp->icmp_pptr = code; 137 code = 0; 138 } else if (type == ICMP_UNREACH && 139 code == ICMP_UNREACH_NEEDFRAG && destifp) { 140 icp->icmp_nextmtu = htons(destifp->if_mtu); 141 } 142 } 143 144 icp->icmp_code = code; 145 bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen); 146 nip = &icp->icmp_ip; 147 nip->ip_len = htons((u_short)(nip->ip_len + oiplen)); 148 149 /* 150 * Now, copy old ip header (without options) 151 * in front of icmp message. 152 */ 153 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 154 panic("icmp len"); 155 m->m_data -= sizeof(struct ip); 156 m->m_len += sizeof(struct ip); 157 m->m_pkthdr.len = m->m_len; 158 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 159 nip = mtod(m, struct ip *); 160 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 161 nip->ip_len = m->m_len; 162 nip->ip_hl = sizeof(struct ip) >> 2; 163 nip->ip_p = IPPROTO_ICMP; 164 nip->ip_tos = 0; 165 icmp_reflect(m); 166 167 freeit: 168 m_freem(n); 169 } 170 171 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET }; 172 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET }; 173 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET }; 174 struct sockaddr_in icmpmask = { 8, 0 }; 175 176 /* 177 * Process a received ICMP message. 178 */ 179 void 180 icmp_input(m, hlen) 181 register struct mbuf *m; 182 int hlen; 183 { 184 register struct icmp *icp; 185 register struct ip *ip = mtod(m, struct ip *); 186 int icmplen = ip->ip_len; 187 register int i; 188 struct in_ifaddr *ia; 189 void (*ctlfunc) __P((int, struct sockaddr *, struct ip *)); 190 int code; 191 192 /* 193 * Locate icmp structure in mbuf, and check 194 * that not corrupted and of at least minimum length. 195 */ 196 #ifdef ICMPPRINTFS 197 if (icmpprintfs) { 198 char buf[4 * sizeof "123"]; 199 strcpy(buf, inet_ntoa(ip->ip_src)); 200 printf("icmp_input from %s to %s, len %d\n", 201 buf, inet_ntoa(ip->ip_dst), icmplen); 202 } 203 #endif 204 if (icmplen < ICMP_MINLEN) { 205 icmpstat.icps_tooshort++; 206 goto freeit; 207 } 208 i = hlen + min(icmplen, ICMP_ADVLENMIN); 209 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 210 icmpstat.icps_tooshort++; 211 return; 212 } 213 ip = mtod(m, struct ip *); 214 m->m_len -= hlen; 215 m->m_data += hlen; 216 icp = mtod(m, struct icmp *); 217 if (in_cksum(m, icmplen)) { 218 icmpstat.icps_checksum++; 219 goto freeit; 220 } 221 m->m_len += hlen; 222 m->m_data -= hlen; 223 224 #ifdef ICMPPRINTFS 225 if (icmpprintfs) 226 printf("icmp_input, type %d code %d\n", icp->icmp_type, 227 icp->icmp_code); 228 #endif 229 230 /* 231 * Message type specific processing. 232 */ 233 if (icp->icmp_type > ICMP_MAXTYPE) 234 goto raw; 235 icmpstat.icps_inhist[icp->icmp_type]++; 236 code = icp->icmp_code; 237 switch (icp->icmp_type) { 238 239 case ICMP_UNREACH: 240 switch (code) { 241 case ICMP_UNREACH_NET: 242 case ICMP_UNREACH_HOST: 243 case ICMP_UNREACH_PROTOCOL: 244 case ICMP_UNREACH_PORT: 245 case ICMP_UNREACH_SRCFAIL: 246 code += PRC_UNREACH_NET; 247 break; 248 249 case ICMP_UNREACH_NEEDFRAG: 250 code = PRC_MSGSIZE; 251 break; 252 253 case ICMP_UNREACH_NET_UNKNOWN: 254 case ICMP_UNREACH_NET_PROHIB: 255 case ICMP_UNREACH_TOSNET: 256 code = PRC_UNREACH_NET; 257 break; 258 259 case ICMP_UNREACH_HOST_UNKNOWN: 260 case ICMP_UNREACH_ISOLATED: 261 case ICMP_UNREACH_HOST_PROHIB: 262 case ICMP_UNREACH_TOSHOST: 263 code = PRC_UNREACH_HOST; 264 break; 265 266 default: 267 goto badcode; 268 } 269 goto deliver; 270 271 case ICMP_TIMXCEED: 272 if (code > 1) 273 goto badcode; 274 code += PRC_TIMXCEED_INTRANS; 275 goto deliver; 276 277 case ICMP_PARAMPROB: 278 if (code > 1) 279 goto badcode; 280 code = PRC_PARAMPROB; 281 goto deliver; 282 283 case ICMP_SOURCEQUENCH: 284 if (code) 285 goto badcode; 286 code = PRC_QUENCH; 287 deliver: 288 /* 289 * Problem with datagram; advise higher level routines. 290 */ 291 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 292 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 293 icmpstat.icps_badlen++; 294 goto freeit; 295 } 296 NTOHS(icp->icmp_ip.ip_len); 297 /* Discard ICMP's in response to multicast packets */ 298 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 299 goto badcode; 300 #ifdef ICMPPRINTFS 301 if (icmpprintfs) 302 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 303 #endif 304 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 305 #ifdef MTUDISC 306 /* 307 * MTU discovery: 308 * If we got a needfrag and there is a host route to the 309 * original destination, and the MTU is not locked, then 310 * set the MTU in the route to the suggested new value 311 * (if given) and then notify as usual. The ULPs will 312 * notice that the MTU has changed and adapt accordingly. 313 * If no new MTU was suggested, then we guess a new one 314 * less than the current value. If the new MTU is 315 * unreasonably small (arbitrarily set at 296), then 316 * we reset the MTU to the interface value and enable the 317 * lock bit, indicating that we are no longer doing MTU 318 * discovery. 319 */ 320 if (code == PRC_MSGSIZE) { 321 struct rtentry *rt; 322 int mtu; 323 324 rt = rtalloc1((struct sockaddr *)&icmpsrc, 0, 325 RTF_CLONING | RTF_PRCLONING); 326 if (rt && (rt->rt_flags & RTF_HOST) 327 && !(rt->rt_rmx.rmx_locks & RTV_MTU)) { 328 mtu = ntohs(icp->icmp_nextmtu); 329 if (!mtu) 330 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu, 331 1); 332 if (!mtu || mtu < 296) { 333 rt->rt_rmx.rmx_mtu = 334 rt->rt_ifp->if_mtu; 335 rt->rt_rmx.rmx_locks |= RTV_MTU; 336 } else if (rt->rt_rmx.rmx_mtu > mtu) { 337 rt->rt_rmx.rmx_mtu = mtu; 338 } 339 } 340 if (rt) 341 RTFREE(rt); 342 } 343 344 #endif /* MTUDISC */ 345 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 346 if (ctlfunc) 347 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 348 &icp->icmp_ip); 349 break; 350 351 badcode: 352 icmpstat.icps_badcode++; 353 break; 354 355 case ICMP_ECHO: 356 icp->icmp_type = ICMP_ECHOREPLY; 357 goto reflect; 358 359 case ICMP_TSTAMP: 360 if (icmplen < ICMP_TSLEN) { 361 icmpstat.icps_badlen++; 362 break; 363 } 364 icp->icmp_type = ICMP_TSTAMPREPLY; 365 icp->icmp_rtime = iptime(); 366 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 367 goto reflect; 368 369 case ICMP_MASKREQ: 370 #define satosin(sa) ((struct sockaddr_in *)(sa)) 371 if (icmpmaskrepl == 0) 372 break; 373 /* 374 * We are not able to respond with all ones broadcast 375 * unless we receive it over a point-to-point interface. 376 */ 377 if (icmplen < ICMP_MASKLEN) 378 break; 379 switch (ip->ip_dst.s_addr) { 380 381 case INADDR_BROADCAST: 382 case INADDR_ANY: 383 icmpdst.sin_addr = ip->ip_src; 384 break; 385 386 default: 387 icmpdst.sin_addr = ip->ip_dst; 388 } 389 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 390 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 391 if (ia == 0) 392 break; 393 icp->icmp_type = ICMP_MASKREPLY; 394 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 395 if (ip->ip_src.s_addr == 0) { 396 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 397 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 398 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 399 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 400 } 401 reflect: 402 ip->ip_len += hlen; /* since ip_input deducts this */ 403 icmpstat.icps_reflect++; 404 icmpstat.icps_outhist[icp->icmp_type]++; 405 icmp_reflect(m); 406 return; 407 408 case ICMP_REDIRECT: 409 if (code > 3) 410 goto badcode; 411 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 412 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 413 icmpstat.icps_badlen++; 414 break; 415 } 416 /* 417 * Short circuit routing redirects to force 418 * immediate change in the kernel's routing 419 * tables. The message is also handed to anyone 420 * listening on a raw socket (e.g. the routing 421 * daemon for use in updating its tables). 422 */ 423 icmpgw.sin_addr = ip->ip_src; 424 icmpdst.sin_addr = icp->icmp_gwaddr; 425 #ifdef ICMPPRINTFS 426 if (icmpprintfs) { 427 char buf[4 * sizeof "123"]; 428 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 429 430 printf("redirect dst %s to %s\n", 431 buf, inet_ntoa(icp->icmp_gwaddr)); 432 } 433 #endif 434 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 435 rtredirect((struct sockaddr *)&icmpsrc, 436 (struct sockaddr *)&icmpdst, 437 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 438 (struct sockaddr *)&icmpgw, (struct rtentry **)0); 439 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 440 break; 441 442 /* 443 * No kernel processing for the following; 444 * just fall through to send to raw listener. 445 */ 446 case ICMP_ECHOREPLY: 447 case ICMP_ROUTERADVERT: 448 case ICMP_ROUTERSOLICIT: 449 case ICMP_TSTAMPREPLY: 450 case ICMP_IREQREPLY: 451 case ICMP_MASKREPLY: 452 default: 453 break; 454 } 455 456 raw: 457 rip_input(m); 458 return; 459 460 freeit: 461 m_freem(m); 462 } 463 464 /* 465 * Reflect the ip packet back to the source 466 */ 467 void 468 icmp_reflect(m) 469 struct mbuf *m; 470 { 471 register struct ip *ip = mtod(m, struct ip *); 472 register struct in_ifaddr *ia; 473 struct in_addr t; 474 struct mbuf *opts = 0; 475 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 476 477 if (!in_canforward(ip->ip_src) && 478 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 479 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 480 m_freem(m); /* Bad return address */ 481 goto done; /* Ip_output() will check for broadcast */ 482 } 483 t = ip->ip_dst; 484 ip->ip_dst = ip->ip_src; 485 /* 486 * If the incoming packet was addressed directly to us, 487 * use dst as the src for the reply. Otherwise (broadcast 488 * or anonymous), use the address which corresponds 489 * to the incoming interface. 490 */ 491 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 492 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 493 break; 494 if ((ia->ia_ifp->if_flags & IFF_BROADCAST) && 495 t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr) 496 break; 497 } 498 icmpdst.sin_addr = t; 499 if (ia == (struct in_ifaddr *)0) 500 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 501 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 502 /* 503 * The following happens if the packet was not addressed to us, 504 * and was received on an interface with no IP address. 505 */ 506 if (ia == (struct in_ifaddr *)0) 507 ia = in_ifaddr; 508 t = IA_SIN(ia)->sin_addr; 509 ip->ip_src = t; 510 ip->ip_ttl = MAXTTL; 511 512 if (optlen > 0) { 513 register u_char *cp; 514 int opt, cnt; 515 u_int len; 516 517 /* 518 * Retrieve any source routing from the incoming packet; 519 * add on any record-route or timestamp options. 520 */ 521 cp = (u_char *) (ip + 1); 522 if ((opts = ip_srcroute()) == 0 && 523 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 524 opts->m_len = sizeof(struct in_addr); 525 mtod(opts, struct in_addr *)->s_addr = 0; 526 } 527 if (opts) { 528 #ifdef ICMPPRINTFS 529 if (icmpprintfs) 530 printf("icmp_reflect optlen %d rt %d => ", 531 optlen, opts->m_len); 532 #endif 533 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 534 opt = cp[IPOPT_OPTVAL]; 535 if (opt == IPOPT_EOL) 536 break; 537 if (opt == IPOPT_NOP) 538 len = 1; 539 else { 540 len = cp[IPOPT_OLEN]; 541 if (len <= 0 || len > cnt) 542 break; 543 } 544 /* 545 * Should check for overflow, but it "can't happen" 546 */ 547 if (opt == IPOPT_RR || opt == IPOPT_TS || 548 opt == IPOPT_SECURITY) { 549 bcopy((caddr_t)cp, 550 mtod(opts, caddr_t) + opts->m_len, len); 551 opts->m_len += len; 552 } 553 } 554 /* Terminate & pad, if necessary */ 555 cnt = opts->m_len % 4; 556 if (cnt) { 557 for (; cnt < 4; cnt++) { 558 *(mtod(opts, caddr_t) + opts->m_len) = 559 IPOPT_EOL; 560 opts->m_len++; 561 } 562 } 563 #ifdef ICMPPRINTFS 564 if (icmpprintfs) 565 printf("%d\n", opts->m_len); 566 #endif 567 } 568 /* 569 * Now strip out original options by copying rest of first 570 * mbuf's data back, and adjust the IP length. 571 */ 572 ip->ip_len -= optlen; 573 ip->ip_hl = sizeof(struct ip) >> 2; 574 m->m_len -= optlen; 575 if (m->m_flags & M_PKTHDR) 576 m->m_pkthdr.len -= optlen; 577 optlen += sizeof(struct ip); 578 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 579 (unsigned)(m->m_len - sizeof(struct ip))); 580 } 581 m->m_flags &= ~(M_BCAST|M_MCAST); 582 icmp_send(m, opts); 583 done: 584 if (opts) 585 (void)m_free(opts); 586 } 587 588 /* 589 * Send an icmp packet back to the ip level, 590 * after supplying a checksum. 591 */ 592 void 593 icmp_send(m, opts) 594 register struct mbuf *m; 595 struct mbuf *opts; 596 { 597 register struct ip *ip = mtod(m, struct ip *); 598 register int hlen; 599 register struct icmp *icp; 600 601 hlen = ip->ip_hl << 2; 602 m->m_data += hlen; 603 m->m_len -= hlen; 604 icp = mtod(m, struct icmp *); 605 icp->icmp_cksum = 0; 606 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 607 m->m_data -= hlen; 608 m->m_len += hlen; 609 #ifdef ICMPPRINTFS 610 if (icmpprintfs) { 611 char buf[4 * sizeof "123"]; 612 strcpy(buf, inet_ntoa(ip->ip_dst)); 613 printf("icmp_send dst %s src %s\n", 614 buf, inet_ntoa(ip->ip_src)); 615 } 616 #endif 617 (void) ip_output(m, opts, NULL, 0, NULL); 618 } 619 620 n_time 621 iptime() 622 { 623 struct timeval atv; 624 u_long t; 625 626 microtime(&atv); 627 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 628 return (htonl(t)); 629 } 630 631 int 632 icmp_sysctl(name, namelen, oldp, oldlenp, newp, newlen) 633 int *name; 634 u_int namelen; 635 void *oldp; 636 size_t *oldlenp; 637 void *newp; 638 size_t newlen; 639 { 640 /* All sysctl names at this level are terminal. */ 641 if (namelen != 1) 642 return (ENOTDIR); /* XXX overloaded */ 643 644 switch (name[0]) { 645 case ICMPCTL_MASKREPL: 646 return (sysctl_int(oldp, oldlenp, newp, newlen, &icmpmaskrepl)); 647 case ICMPCTL_STATS: 648 return (sysctl_rdstruct(oldp, oldlenp, newp, &icmpstat, 649 sizeof icmpstat)); 650 default: 651 return (ENOPROTOOPT); 652 } 653 /* NOTREACHED */ 654 } 655 656 #ifdef MTUDISC 657 /* 658 * Return the next larger or smaller MTU plateau (table from RFC 1191) 659 * given current value MTU. If DIR is less than zero, a larger plateau 660 * is returned; otherwise, a smaller value is returned. 661 */ 662 int 663 ip_next_mtu(mtu, dir) 664 int mtu; 665 int dir; 666 { 667 static int mtutab[] = { 668 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296, 669 68, 0 670 }; 671 int i; 672 673 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) { 674 if (mtu >= mtutab[i]) 675 break; 676 } 677 678 if (dir < 0) { 679 if (i == 0) { 680 return 0; 681 } else { 682 return mtutab[i - 1]; 683 } 684 } else { 685 if (mtutab[i] == 0) { 686 return 0; 687 } else if(mtu > mtutab[i]) { 688 return mtutab[i]; 689 } else { 690 return mtutab[i + 1]; 691 } 692 } 693 } 694 #endif /* MTUDISC */ 695