Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_icmp.c
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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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