ip_icmp.c revision 1.25.2.2
1 /* $NetBSD: ip_icmp.c,v 1.25.2.2 1998/05/09 03:33:00 mycroft Exp $ */ 2 3 /* 4 * Copyright (c) 1982, 1986, 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 36 */ 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/malloc.h> 41 #include <sys/mbuf.h> 42 #include <sys/protosw.h> 43 #include <sys/socket.h> 44 #include <sys/time.h> 45 #include <sys/kernel.h> 46 #include <sys/proc.h> 47 48 #include <vm/vm.h> 49 #include <sys/sysctl.h> 50 51 #include <net/if.h> 52 #include <net/route.h> 53 54 #include <netinet/in.h> 55 #include <netinet/in_systm.h> 56 #include <netinet/in_var.h> 57 #include <netinet/ip.h> 58 #include <netinet/ip_icmp.h> 59 #include <netinet/ip_var.h> 60 #include <netinet/icmp_var.h> 61 62 #include <machine/stdarg.h> 63 64 /* 65 * ICMP routines: error generation, receive packet processing, and 66 * routines to turnaround packets back to the originator, and 67 * host table maintenance routines. 68 */ 69 70 int icmpmaskrepl = 0; 71 #ifdef ICMPPRINTFS 72 int icmpprintfs = 0; 73 #endif 74 75 extern struct protosw inetsw[]; 76 77 static void icmp_mtudisc __P((struct icmp *)); 78 static void icmp_mtudisc_timeout __P((struct rtentry *, struct rttimer *)); 79 80 /* 81 * Generate an error packet of type error 82 * in response to bad packet ip. 83 */ 84 void 85 icmp_error(n, type, code, dest, destifp) 86 struct mbuf *n; 87 int type, code; 88 n_long dest; 89 struct ifnet *destifp; 90 { 91 register struct ip *oip = mtod(n, struct ip *), *nip; 92 register unsigned oiplen = oip->ip_hl << 2; 93 register struct icmp *icp; 94 register struct mbuf *m; 95 unsigned icmplen; 96 97 #ifdef ICMPPRINTFS 98 if (icmpprintfs) 99 printf("icmp_error(%x, %d, %d)\n", oip, type, code); 100 #endif 101 if (type != ICMP_REDIRECT) 102 icmpstat.icps_error++; 103 /* 104 * Don't send error if not the first fragment of message. 105 * Don't error if the old packet protocol was ICMP 106 * error message, only known informational types. 107 */ 108 if (oip->ip_off &~ (IP_MF|IP_DF)) 109 goto freeit; 110 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 111 n->m_len >= oiplen + ICMP_MINLEN && 112 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 113 icmpstat.icps_oldicmp++; 114 goto freeit; 115 } 116 /* Don't send error in response to a multicast or broadcast packet */ 117 if (n->m_flags & (M_BCAST|M_MCAST)) 118 goto freeit; 119 /* 120 * First, formulate icmp message 121 */ 122 m = m_gethdr(M_DONTWAIT, MT_HEADER); 123 if (m == NULL) 124 goto freeit; 125 icmplen = oiplen + min(8, oip->ip_len); 126 m->m_len = icmplen + ICMP_MINLEN; 127 MH_ALIGN(m, m->m_len); 128 icp = mtod(m, struct icmp *); 129 if ((u_int)type > ICMP_MAXTYPE) 130 panic("icmp_error"); 131 icmpstat.icps_outhist[type]++; 132 icp->icmp_type = type; 133 if (type == ICMP_REDIRECT) 134 icp->icmp_gwaddr.s_addr = dest; 135 else { 136 icp->icmp_void = 0; 137 /* 138 * The following assignments assume an overlay with the 139 * zeroed icmp_void field. 140 */ 141 if (type == ICMP_PARAMPROB) { 142 icp->icmp_pptr = code; 143 code = 0; 144 } else if (type == ICMP_UNREACH && 145 code == ICMP_UNREACH_NEEDFRAG && destifp) 146 icp->icmp_nextmtu = htons(destifp->if_mtu); 147 } 148 149 icp->icmp_code = code; 150 bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen); 151 nip = &icp->icmp_ip; 152 nip->ip_len = htons((u_int16_t)(nip->ip_len + oiplen)); 153 154 /* 155 * Now, copy old ip header (without options) 156 * in front of icmp message. 157 */ 158 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 159 panic("icmp len"); 160 m->m_data -= sizeof(struct ip); 161 m->m_len += sizeof(struct ip); 162 m->m_pkthdr.len = m->m_len; 163 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 164 nip = mtod(m, struct ip *); 165 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 166 nip->ip_len = m->m_len; 167 nip->ip_hl = sizeof(struct ip) >> 2; 168 nip->ip_p = IPPROTO_ICMP; 169 nip->ip_tos = 0; 170 icmp_reflect(m); 171 172 freeit: 173 m_freem(n); 174 } 175 176 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET }; 177 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET }; 178 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET }; 179 struct sockaddr_in icmpmask = { 8, 0 }; 180 181 /* 182 * Process a received ICMP message. 183 */ 184 void 185 #if __STDC__ 186 icmp_input(struct mbuf *m, ...) 187 #else 188 icmp_input(m, va_alist) 189 struct mbuf *m; 190 va_dcl 191 #endif 192 { 193 register struct icmp *icp; 194 register struct ip *ip = mtod(m, struct ip *); 195 int icmplen = ip->ip_len; 196 register int i; 197 struct in_ifaddr *ia; 198 void *(*ctlfunc) __P((int, struct sockaddr *, void *)); 199 int code; 200 extern u_char ip_protox[]; 201 int hlen; 202 va_list ap; 203 204 va_start(ap, m); 205 hlen = va_arg(ap, int); 206 va_end(ap); 207 208 /* 209 * Locate icmp structure in mbuf, and check 210 * that not corrupted and of at least minimum length. 211 */ 212 #ifdef ICMPPRINTFS 213 if (icmpprintfs) 214 printf("icmp_input from %x to %x, len %d\n", 215 ntohl(ip->ip_src.s_addr), ntohl(ip->ip_dst.s_addr), 216 icmplen); 217 #endif 218 if (icmplen < ICMP_MINLEN) { 219 icmpstat.icps_tooshort++; 220 goto freeit; 221 } 222 i = hlen + min(icmplen, ICMP_ADVLENMIN); 223 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 224 icmpstat.icps_tooshort++; 225 return; 226 } 227 ip = mtod(m, struct ip *); 228 m->m_len -= hlen; 229 m->m_data += hlen; 230 icp = mtod(m, struct icmp *); 231 if (in_cksum(m, icmplen)) { 232 icmpstat.icps_checksum++; 233 goto freeit; 234 } 235 m->m_len += hlen; 236 m->m_data -= hlen; 237 238 #ifdef ICMPPRINTFS 239 /* 240 * Message type specific processing. 241 */ 242 if (icmpprintfs) 243 printf("icmp_input, type %d code %d\n", icp->icmp_type, 244 icp->icmp_code); 245 #endif 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 default: 280 goto badcode; 281 } 282 goto deliver; 283 284 case ICMP_TIMXCEED: 285 if (code > 1) 286 goto badcode; 287 code += PRC_TIMXCEED_INTRANS; 288 goto deliver; 289 290 case ICMP_PARAMPROB: 291 if (code > 1) 292 goto badcode; 293 code = PRC_PARAMPROB; 294 goto deliver; 295 296 case ICMP_SOURCEQUENCH: 297 if (code) 298 goto badcode; 299 code = PRC_QUENCH; 300 goto deliver; 301 302 deliver: 303 /* 304 * Problem with datagram; advise higher level routines. 305 */ 306 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 307 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 308 icmpstat.icps_badlen++; 309 goto freeit; 310 } 311 if (IN_MULTICAST(icp->icmp_ip.ip_dst.s_addr)) 312 goto badcode; 313 NTOHS(icp->icmp_ip.ip_len); 314 #ifdef ICMPPRINTFS 315 if (icmpprintfs) 316 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 317 #endif 318 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 319 if (code == PRC_MSGSIZE && ip_mtudisc) 320 icmp_mtudisc(icp); 321 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 322 if (ctlfunc) 323 (*ctlfunc)(code, sintosa(&icmpsrc), &icp->icmp_ip); 324 break; 325 326 badcode: 327 icmpstat.icps_badcode++; 328 break; 329 330 case ICMP_ECHO: 331 icp->icmp_type = ICMP_ECHOREPLY; 332 goto reflect; 333 334 case ICMP_TSTAMP: 335 if (icmplen < ICMP_TSLEN) { 336 icmpstat.icps_badlen++; 337 break; 338 } 339 icp->icmp_type = ICMP_TSTAMPREPLY; 340 icp->icmp_rtime = iptime(); 341 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 342 goto reflect; 343 344 case ICMP_MASKREQ: 345 if (icmpmaskrepl == 0) 346 break; 347 /* 348 * We are not able to respond with all ones broadcast 349 * unless we receive it over a point-to-point interface. 350 */ 351 if (icmplen < ICMP_MASKLEN) { 352 icmpstat.icps_badlen++; 353 break; 354 } 355 if (ip->ip_dst.s_addr == INADDR_BROADCAST || 356 in_nullhost(ip->ip_dst)) 357 icmpdst.sin_addr = ip->ip_src; 358 else 359 icmpdst.sin_addr = ip->ip_dst; 360 ia = ifatoia(ifaof_ifpforaddr(sintosa(&icmpdst), 361 m->m_pkthdr.rcvif)); 362 if (ia == 0) 363 break; 364 icp->icmp_type = ICMP_MASKREPLY; 365 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 366 if (in_nullhost(ip->ip_src)) { 367 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 368 ip->ip_src = ia->ia_broadaddr.sin_addr; 369 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 370 ip->ip_src = ia->ia_dstaddr.sin_addr; 371 } 372 reflect: 373 ip->ip_len += hlen; /* since ip_input deducts this */ 374 icmpstat.icps_reflect++; 375 icmpstat.icps_outhist[icp->icmp_type]++; 376 icmp_reflect(m); 377 return; 378 379 case ICMP_REDIRECT: 380 if (code > 3) 381 goto badcode; 382 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 383 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 384 icmpstat.icps_badlen++; 385 break; 386 } 387 /* 388 * Short circuit routing redirects to force 389 * immediate change in the kernel's routing 390 * tables. The message is also handed to anyone 391 * listening on a raw socket (e.g. the routing 392 * daemon for use in updating its tables). 393 */ 394 icmpgw.sin_addr = ip->ip_src; 395 icmpdst.sin_addr = icp->icmp_gwaddr; 396 #ifdef ICMPPRINTFS 397 if (icmpprintfs) 398 printf("redirect dst %x to %x\n", icp->icmp_ip.ip_dst, 399 icp->icmp_gwaddr); 400 #endif 401 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 402 rtredirect(sintosa(&icmpsrc), sintosa(&icmpdst), 403 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 404 sintosa(&icmpgw), (struct rtentry **)0); 405 pfctlinput(PRC_REDIRECT_HOST, sintosa(&icmpsrc)); 406 break; 407 408 /* 409 * No kernel processing for the following; 410 * just fall through to send to raw listener. 411 */ 412 case ICMP_ECHOREPLY: 413 case ICMP_ROUTERADVERT: 414 case ICMP_ROUTERSOLICIT: 415 case ICMP_TSTAMPREPLY: 416 case ICMP_IREQREPLY: 417 case ICMP_MASKREPLY: 418 default: 419 break; 420 } 421 422 raw: 423 rip_input(m); 424 return; 425 426 freeit: 427 m_freem(m); 428 } 429 430 /* 431 * Reflect the ip packet back to the source 432 */ 433 void 434 icmp_reflect(m) 435 struct mbuf *m; 436 { 437 register struct ip *ip = mtod(m, struct ip *); 438 register struct in_ifaddr *ia; 439 struct in_addr t; 440 struct mbuf *opts = 0; 441 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 442 443 if (!in_canforward(ip->ip_src) && 444 ((ip->ip_src.s_addr & IN_CLASSA_NET) != 445 htonl(IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 446 m_freem(m); /* Bad return address */ 447 goto done; /* ip_output() will check for broadcast */ 448 } 449 t = ip->ip_dst; 450 ip->ip_dst = ip->ip_src; 451 /* 452 * If the incoming packet was addressed directly to us, 453 * use dst as the src for the reply. Otherwise (broadcast 454 * or anonymous), use the address which corresponds 455 * to the incoming interface. 456 */ 457 for (ia = in_ifaddr.tqh_first; ia; ia = ia->ia_list.tqe_next) { 458 if (in_hosteq(t, ia->ia_addr.sin_addr)) 459 break; 460 if ((ia->ia_ifp->if_flags & IFF_BROADCAST) && 461 in_hosteq(t, ia->ia_broadaddr.sin_addr)) 462 break; 463 } 464 icmpdst.sin_addr = t; 465 if (ia == (struct in_ifaddr *)0) 466 ia = ifatoia(ifaof_ifpforaddr(sintosa(&icmpdst), 467 m->m_pkthdr.rcvif)); 468 /* 469 * The following happens if the packet was not addressed to us, 470 * and was received on an interface with no IP address. 471 */ 472 if (ia == (struct in_ifaddr *)0) 473 ia = in_ifaddr.tqh_first; 474 t = ia->ia_addr.sin_addr; 475 ip->ip_src = t; 476 ip->ip_ttl = MAXTTL; 477 478 if (optlen > 0) { 479 register u_char *cp; 480 int opt, cnt; 481 u_int len; 482 483 /* 484 * Retrieve any source routing from the incoming packet; 485 * add on any record-route or timestamp options. 486 */ 487 cp = (u_char *) (ip + 1); 488 if ((opts = ip_srcroute()) == 0 && 489 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 490 opts->m_len = sizeof(struct in_addr); 491 *mtod(opts, struct in_addr *) = zeroin_addr; 492 } 493 if (opts) { 494 #ifdef ICMPPRINTFS 495 if (icmpprintfs) 496 printf("icmp_reflect optlen %d rt %d => ", 497 optlen, opts->m_len); 498 #endif 499 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 500 opt = cp[IPOPT_OPTVAL]; 501 if (opt == IPOPT_EOL) 502 break; 503 if (opt == IPOPT_NOP) 504 len = 1; 505 else { 506 len = cp[IPOPT_OLEN]; 507 if (len <= 0 || len > cnt) 508 break; 509 } 510 /* 511 * Should check for overflow, but it "can't happen" 512 */ 513 if (opt == IPOPT_RR || opt == IPOPT_TS || 514 opt == IPOPT_SECURITY) { 515 bcopy((caddr_t)cp, 516 mtod(opts, caddr_t) + opts->m_len, len); 517 opts->m_len += len; 518 } 519 } 520 /* Terminate & pad, if necessary */ 521 if ((cnt = opts->m_len % 4) != 0) { 522 for (; cnt < 4; cnt++) { 523 *(mtod(opts, caddr_t) + opts->m_len) = 524 IPOPT_EOL; 525 opts->m_len++; 526 } 527 } 528 #ifdef ICMPPRINTFS 529 if (icmpprintfs) 530 printf("%d\n", opts->m_len); 531 #endif 532 } 533 /* 534 * Now strip out original options by copying rest of first 535 * mbuf's data back, and adjust the IP length. 536 */ 537 ip->ip_len -= optlen; 538 ip->ip_hl = sizeof(struct ip) >> 2; 539 m->m_len -= optlen; 540 if (m->m_flags & M_PKTHDR) 541 m->m_pkthdr.len -= optlen; 542 optlen += sizeof(struct ip); 543 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 544 (unsigned)(m->m_len - sizeof(struct ip))); 545 } 546 m->m_flags &= ~(M_BCAST|M_MCAST); 547 icmp_send(m, opts); 548 done: 549 if (opts) 550 (void)m_free(opts); 551 } 552 553 /* 554 * Send an icmp packet back to the ip level, 555 * after supplying a checksum. 556 */ 557 void 558 icmp_send(m, opts) 559 register struct mbuf *m; 560 struct mbuf *opts; 561 { 562 register struct ip *ip = mtod(m, struct ip *); 563 register int hlen; 564 register struct icmp *icp; 565 566 hlen = ip->ip_hl << 2; 567 m->m_data += hlen; 568 m->m_len -= hlen; 569 icp = mtod(m, struct icmp *); 570 icp->icmp_cksum = 0; 571 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 572 m->m_data -= hlen; 573 m->m_len += hlen; 574 #ifdef ICMPPRINTFS 575 if (icmpprintfs) 576 printf("icmp_send dst %x src %x\n", ip->ip_dst, ip->ip_src); 577 #endif 578 (void) ip_output(m, opts, NULL, 0, NULL); 579 } 580 581 n_time 582 iptime() 583 { 584 struct timeval atv; 585 u_long t; 586 587 microtime(&atv); 588 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 589 return (htonl(t)); 590 } 591 592 int 593 icmp_sysctl(name, namelen, oldp, oldlenp, newp, newlen) 594 int *name; 595 u_int namelen; 596 void *oldp; 597 size_t *oldlenp; 598 void *newp; 599 size_t newlen; 600 { 601 602 /* All sysctl names at this level are terminal. */ 603 if (namelen != 1) 604 return (ENOTDIR); 605 606 switch (name[0]) { 607 case ICMPCTL_MASKREPL: 608 return (sysctl_int(oldp, oldlenp, newp, newlen, &icmpmaskrepl)); 609 default: 610 return (ENOPROTOOPT); 611 } 612 /* NOTREACHED */ 613 } 614 615 static void 616 icmp_mtudisc(icp) 617 struct icmp *icp; 618 { 619 struct rtentry *rt; 620 struct sockaddr *dst = sintosa(&icmpsrc); 621 u_long mtu = ntohs(icp->icmp_nextmtu); /* Why a long? IPv6 */ 622 int error; 623 624 /* Table of common MTUs: */ 625 626 static u_long mtu_table[] = {65535, 65280, 32000, 17914, 9180, 8166, 627 4352, 2002, 1492, 1006, 508, 296, 68, 0}; 628 629 rt = rtalloc1(dst, 1); 630 if (rt == 0) 631 return; 632 633 /* If we didn't get a host route, allocate one */ 634 635 if ((rt->rt_flags & RTF_HOST) == 0) { 636 struct rtentry *nrt; 637 638 error = rtrequest((int) RTM_ADD, dst, 639 (struct sockaddr *) rt->rt_gateway, 640 (struct sockaddr *) 0, 641 RTF_GATEWAY | RTF_HOST | RTF_DYNAMIC, &nrt); 642 if (error) { 643 rtfree(rt); 644 rtfree(nrt); 645 return; 646 } 647 nrt->rt_rmx = rt->rt_rmx; 648 rtfree(rt); 649 rt = nrt; 650 } 651 652 error = rt_timer_add(rt, icmp_mtudisc_timeout, ip_mtudisc_timeout_q); 653 if (error) { 654 rtfree(rt); 655 return; 656 } 657 658 if (mtu == 0) { 659 int i = 0; 660 661 mtu = icp->icmp_ip.ip_len; /* NTOHS happened in deliver: */ 662 /* Some 4.2BSD-based routers incorrectly adjust the ip_len */ 663 if (mtu > rt->rt_rmx.rmx_mtu && rt->rt_rmx.rmx_mtu != 0) 664 mtu -= (icp->icmp_ip.ip_hl << 2); 665 666 /* If we still can't guess a value, try the route */ 667 668 if (mtu == 0) { 669 mtu = rt->rt_rmx.rmx_mtu; 670 671 /* If no route mtu, default to the interface mtu */ 672 673 if (mtu == 0) 674 mtu = rt->rt_ifp->if_mtu; 675 } 676 677 for (i = 0; i < sizeof(mtu_table) / sizeof(mtu_table[0]); i++) 678 if (mtu > mtu_table[i]) { 679 mtu = mtu_table[i]; 680 break; 681 } 682 } 683 684 /* 685 * XXX: RTV_MTU is overloaded, since the admin can set it 686 * to turn off PMTU for a route, and the kernel can 687 * set it to indicate a serious problem with PMTU 688 * on a route. We should be using a separate flag 689 * for the kernel to indicate this. 690 */ 691 692 if ((rt->rt_rmx.rmx_locks & RTV_MTU) == 0) { 693 if (mtu < 296 || mtu > rt->rt_ifp->if_mtu) 694 rt->rt_rmx.rmx_locks |= RTV_MTU; 695 else if (rt->rt_rmx.rmx_mtu > mtu || 696 rt->rt_rmx.rmx_mtu == 0) 697 rt->rt_rmx.rmx_mtu = mtu; 698 } 699 700 if (rt) 701 rtfree(rt); 702 } 703 704 705 static void 706 icmp_mtudisc_timeout(rt, r) 707 struct rtentry *rt; 708 struct rttimer *r; 709 { 710 if (rt == NULL) 711 panic("icmp_mtudisc_timeout: bad route to timeout"); 712 if ((rt->rt_flags & (RTF_DYNAMIC | RTF_HOST)) == 713 (RTF_DYNAMIC | RTF_HOST)) { 714 rtrequest((int) RTM_DELETE, (struct sockaddr *)rt_key(rt), 715 rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0); 716 } else { 717 if ((rt->rt_rmx.rmx_locks & RTV_MTU) == 0) { 718 rt->rt_rmx.rmx_mtu = 0; 719 } 720 } 721 } 722
Indexes created Fri Oct 03 02:09:57 GMT 2025