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 1.39.2.19 2003/01/24 05:11:34 sam Exp $ 35 * $DragonFly: src/sys/netinet/ip_icmp.c,v 1.5 2003/08/23 11:18:00 rob Exp $ 36 */ 37 38 #include "opt_ipsec.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/mbuf.h> 43 #include <sys/protosw.h> 44 #include <sys/socket.h> 45 #include <sys/time.h> 46 #include <sys/kernel.h> 47 #include <sys/sysctl.h> 48 49 #include <net/if.h> 50 #include <net/if_types.h> 51 #include <net/route.h> 52 53 #define _IP_VHL 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 #ifdef IPSEC 63 #include <netinet6/ipsec.h> 64 #include <netproto/key/key.h> 65 #endif 66 67 #ifdef FAST_IPSEC 68 #include <netipsec/ipsec.h> 69 #include <netipsec/key.h> 70 #define IPSEC 71 #endif 72 73 /* 74 * ICMP routines: error generation, receive packet processing, and 75 * routines to turnaround packets back to the originator, and 76 * host table maintenance routines. 77 */ 78 79 static struct icmpstat icmpstat; 80 SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, 81 &icmpstat, icmpstat, ""); 82 83 static int icmpmaskrepl = 0; 84 SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, 85 &icmpmaskrepl, 0, ""); 86 87 static int drop_redirect = 0; 88 SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, 89 &drop_redirect, 0, ""); 90 91 static int log_redirect = 0; 92 SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, 93 &log_redirect, 0, ""); 94 95 #ifdef ICMP_BANDLIM 96 97 /* 98 * ICMP error-response bandwidth limiting sysctl. If not enabled, sysctl 99 * variable content is -1 and read-only. 100 */ 101 102 static int icmplim = 200; 103 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, 104 &icmplim, 0, ""); 105 #else 106 107 static int icmplim = -1; 108 SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD, 109 &icmplim, 0, ""); 110 111 #endif 112 113 static int icmplim_output = 1; 114 SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, 115 &icmplim_output, 0, ""); 116 117 /* 118 * ICMP broadcast echo sysctl 119 */ 120 121 static int icmpbmcastecho = 0; 122 SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW, 123 &icmpbmcastecho, 0, ""); 124 125 126 #ifdef ICMPPRINTFS 127 int icmpprintfs = 0; 128 #endif 129 130 static void icmp_reflect (struct mbuf *); 131 static void icmp_send (struct mbuf *, struct mbuf *, struct route *); 132 static int ip_next_mtu (int, int); 133 134 extern struct protosw inetsw[]; 135 136 /* 137 * Generate an error packet of type error 138 * in response to bad packet ip. 139 */ 140 void 141 icmp_error(n, type, code, dest, destifp) 142 struct mbuf *n; 143 int type, code; 144 n_long dest; 145 struct ifnet *destifp; 146 { 147 struct ip *oip = mtod(n, struct ip *), *nip; 148 unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2; 149 struct icmp *icp; 150 struct mbuf *m; 151 unsigned icmplen; 152 153 #ifdef ICMPPRINTFS 154 if (icmpprintfs) 155 printf("icmp_error(%p, %x, %d)\n", oip, type, code); 156 #endif 157 if (type != ICMP_REDIRECT) 158 icmpstat.icps_error++; 159 /* 160 * Don't send error if not the first fragment of message. 161 * Don't error if the old packet protocol was ICMP 162 * error message, only known informational types. 163 */ 164 if (oip->ip_off &~ (IP_MF|IP_DF)) 165 goto freeit; 166 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 167 n->m_len >= oiplen + ICMP_MINLEN && 168 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 169 icmpstat.icps_oldicmp++; 170 goto freeit; 171 } 172 /* Don't send error in response to a multicast or broadcast packet */ 173 if (n->m_flags & (M_BCAST|M_MCAST)) 174 goto freeit; 175 /* 176 * First, formulate icmp message 177 */ 178 m = m_gethdr(M_DONTWAIT, MT_HEADER); 179 if (m == NULL) 180 goto freeit; 181 icmplen = min(oiplen + 8, oip->ip_len); 182 if (icmplen < sizeof(struct ip)) 183 panic("icmp_error: bad length"); 184 m->m_len = icmplen + ICMP_MINLEN; 185 MH_ALIGN(m, m->m_len); 186 icp = mtod(m, struct icmp *); 187 if ((u_int)type > ICMP_MAXTYPE) 188 panic("icmp_error"); 189 icmpstat.icps_outhist[type]++; 190 icp->icmp_type = type; 191 if (type == ICMP_REDIRECT) 192 icp->icmp_gwaddr.s_addr = dest; 193 else { 194 icp->icmp_void = 0; 195 /* 196 * The following assignments assume an overlay with the 197 * zeroed icmp_void field. 198 */ 199 if (type == ICMP_PARAMPROB) { 200 icp->icmp_pptr = code; 201 code = 0; 202 } else if (type == ICMP_UNREACH && 203 code == ICMP_UNREACH_NEEDFRAG && destifp) { 204 icp->icmp_nextmtu = htons(destifp->if_mtu); 205 } 206 } 207 208 icp->icmp_code = code; 209 m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip); 210 nip = &icp->icmp_ip; 211 212 /* 213 * Convert fields to network representation. 214 */ 215 HTONS(nip->ip_len); 216 HTONS(nip->ip_off); 217 218 /* 219 * Now, copy old ip header (without options) 220 * in front of icmp message. 221 */ 222 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 223 panic("icmp len"); 224 m->m_data -= sizeof(struct ip); 225 m->m_len += sizeof(struct ip); 226 m->m_pkthdr.len = m->m_len; 227 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 228 nip = mtod(m, struct ip *); 229 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 230 nip->ip_len = m->m_len; 231 nip->ip_vhl = IP_VHL_BORING; 232 nip->ip_p = IPPROTO_ICMP; 233 nip->ip_tos = 0; 234 icmp_reflect(m); 235 236 freeit: 237 m_freem(n); 238 } 239 240 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET }; 241 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET }; 242 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET }; 243 244 /* 245 * Process a received ICMP message. 246 */ 247 void 248 icmp_input(m, off, proto) 249 struct mbuf *m; 250 int off, proto; 251 { 252 int hlen = off; 253 struct icmp *icp; 254 struct ip *ip = mtod(m, struct ip *); 255 int icmplen = ip->ip_len; 256 int i; 257 struct in_ifaddr *ia; 258 void (*ctlfunc) (int, struct sockaddr *, void *); 259 int code; 260 261 /* 262 * Locate icmp structure in mbuf, and check 263 * that not corrupted and of at least minimum length. 264 */ 265 #ifdef ICMPPRINTFS 266 if (icmpprintfs) { 267 char buf[4 * sizeof "123"]; 268 strcpy(buf, inet_ntoa(ip->ip_src)); 269 printf("icmp_input from %s to %s, len %d\n", 270 buf, inet_ntoa(ip->ip_dst), icmplen); 271 } 272 #endif 273 if (icmplen < ICMP_MINLEN) { 274 icmpstat.icps_tooshort++; 275 goto freeit; 276 } 277 i = hlen + min(icmplen, ICMP_ADVLENMIN); 278 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 279 icmpstat.icps_tooshort++; 280 return; 281 } 282 ip = mtod(m, struct ip *); 283 m->m_len -= hlen; 284 m->m_data += hlen; 285 icp = mtod(m, struct icmp *); 286 if (in_cksum(m, icmplen)) { 287 icmpstat.icps_checksum++; 288 goto freeit; 289 } 290 m->m_len += hlen; 291 m->m_data -= hlen; 292 293 if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 294 /* 295 * Deliver very specific ICMP type only. 296 */ 297 switch (icp->icmp_type) { 298 case ICMP_UNREACH: 299 case ICMP_TIMXCEED: 300 break; 301 default: 302 goto freeit; 303 } 304 } 305 306 #ifdef ICMPPRINTFS 307 if (icmpprintfs) 308 printf("icmp_input, type %d code %d\n", icp->icmp_type, 309 icp->icmp_code); 310 #endif 311 312 /* 313 * Message type specific processing. 314 */ 315 if (icp->icmp_type > ICMP_MAXTYPE) 316 goto raw; 317 icmpstat.icps_inhist[icp->icmp_type]++; 318 code = icp->icmp_code; 319 switch (icp->icmp_type) { 320 321 case ICMP_UNREACH: 322 switch (code) { 323 case ICMP_UNREACH_NET: 324 case ICMP_UNREACH_HOST: 325 case ICMP_UNREACH_SRCFAIL: 326 case ICMP_UNREACH_NET_UNKNOWN: 327 case ICMP_UNREACH_HOST_UNKNOWN: 328 case ICMP_UNREACH_ISOLATED: 329 case ICMP_UNREACH_TOSNET: 330 case ICMP_UNREACH_TOSHOST: 331 case ICMP_UNREACH_HOST_PRECEDENCE: 332 case ICMP_UNREACH_PRECEDENCE_CUTOFF: 333 code = PRC_UNREACH_NET; 334 break; 335 336 case ICMP_UNREACH_NEEDFRAG: 337 code = PRC_MSGSIZE; 338 break; 339 340 /* 341 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. 342 * Treat subcodes 2,3 as immediate RST 343 */ 344 case ICMP_UNREACH_PROTOCOL: 345 case ICMP_UNREACH_PORT: 346 code = PRC_UNREACH_PORT; 347 break; 348 349 case ICMP_UNREACH_NET_PROHIB: 350 case ICMP_UNREACH_HOST_PROHIB: 351 case ICMP_UNREACH_FILTER_PROHIB: 352 code = PRC_UNREACH_ADMIN_PROHIB; 353 break; 354 355 default: 356 goto badcode; 357 } 358 goto deliver; 359 360 case ICMP_TIMXCEED: 361 if (code > 1) 362 goto badcode; 363 code += PRC_TIMXCEED_INTRANS; 364 goto deliver; 365 366 case ICMP_PARAMPROB: 367 if (code > 1) 368 goto badcode; 369 code = PRC_PARAMPROB; 370 goto deliver; 371 372 case ICMP_SOURCEQUENCH: 373 if (code) 374 goto badcode; 375 code = PRC_QUENCH; 376 deliver: 377 /* 378 * Problem with datagram; advise higher level routines. 379 */ 380 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 381 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) { 382 icmpstat.icps_badlen++; 383 goto freeit; 384 } 385 NTOHS(icp->icmp_ip.ip_len); 386 /* Discard ICMP's in response to multicast packets */ 387 if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) 388 goto badcode; 389 #ifdef ICMPPRINTFS 390 if (icmpprintfs) 391 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 392 #endif 393 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 394 #if 1 395 /* 396 * MTU discovery: 397 * If we got a needfrag and there is a host route to the 398 * original destination, and the MTU is not locked, then 399 * set the MTU in the route to the suggested new value 400 * (if given) and then notify as usual. The ULPs will 401 * notice that the MTU has changed and adapt accordingly. 402 * If no new MTU was suggested, then we guess a new one 403 * less than the current value. If the new MTU is 404 * unreasonably small (arbitrarily set at 296), then 405 * we reset the MTU to the interface value and enable the 406 * lock bit, indicating that we are no longer doing MTU 407 * discovery. 408 */ 409 if (code == PRC_MSGSIZE) { 410 struct rtentry *rt; 411 int mtu; 412 413 rt = rtalloc1((struct sockaddr *)&icmpsrc, 0, 414 RTF_CLONING | RTF_PRCLONING); 415 if (rt && (rt->rt_flags & RTF_HOST) 416 && !(rt->rt_rmx.rmx_locks & RTV_MTU)) { 417 mtu = ntohs(icp->icmp_nextmtu); 418 if (!mtu) 419 mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu, 420 1); 421 #ifdef DEBUG_MTUDISC 422 printf("MTU for %s reduced to %d\n", 423 inet_ntoa(icmpsrc.sin_addr), mtu); 424 #endif 425 if (mtu < 296) { 426 /* rt->rt_rmx.rmx_mtu = 427 rt->rt_ifp->if_mtu; */ 428 rt->rt_rmx.rmx_locks |= RTV_MTU; 429 } else if (rt->rt_rmx.rmx_mtu > mtu) { 430 rt->rt_rmx.rmx_mtu = mtu; 431 } 432 } 433 if (rt) 434 RTFREE(rt); 435 } 436 437 #endif 438 /* 439 * XXX if the packet contains [IPv4 AH TCP], we can't make a 440 * notification to TCP layer. 441 */ 442 ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput; 443 if (ctlfunc) 444 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc, 445 (void *)&icp->icmp_ip); 446 break; 447 448 badcode: 449 icmpstat.icps_badcode++; 450 break; 451 452 case ICMP_ECHO: 453 if (!icmpbmcastecho 454 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 455 icmpstat.icps_bmcastecho++; 456 break; 457 } 458 icp->icmp_type = ICMP_ECHOREPLY; 459 #ifdef ICMP_BANDLIM 460 if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) 461 goto freeit; 462 else 463 #endif 464 goto reflect; 465 466 case ICMP_TSTAMP: 467 if (!icmpbmcastecho 468 && (m->m_flags & (M_MCAST | M_BCAST)) != 0) { 469 icmpstat.icps_bmcasttstamp++; 470 break; 471 } 472 if (icmplen < ICMP_TSLEN) { 473 icmpstat.icps_badlen++; 474 break; 475 } 476 icp->icmp_type = ICMP_TSTAMPREPLY; 477 icp->icmp_rtime = iptime(); 478 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 479 #ifdef ICMP_BANDLIM 480 if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) 481 goto freeit; 482 else 483 #endif 484 goto reflect; 485 486 case ICMP_MASKREQ: 487 if (icmpmaskrepl == 0) 488 break; 489 /* 490 * We are not able to respond with all ones broadcast 491 * unless we receive it over a point-to-point interface. 492 */ 493 if (icmplen < ICMP_MASKLEN) 494 break; 495 switch (ip->ip_dst.s_addr) { 496 497 case INADDR_BROADCAST: 498 case INADDR_ANY: 499 icmpdst.sin_addr = ip->ip_src; 500 break; 501 502 default: 503 icmpdst.sin_addr = ip->ip_dst; 504 } 505 ia = (struct in_ifaddr *)ifaof_ifpforaddr( 506 (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif); 507 if (ia == 0) 508 break; 509 if (ia->ia_ifp == 0) 510 break; 511 icp->icmp_type = ICMP_MASKREPLY; 512 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 513 if (ip->ip_src.s_addr == 0) { 514 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 515 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 516 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 517 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 518 } 519 reflect: 520 ip->ip_len += hlen; /* since ip_input deducts this */ 521 icmpstat.icps_reflect++; 522 icmpstat.icps_outhist[icp->icmp_type]++; 523 icmp_reflect(m); 524 return; 525 526 case ICMP_REDIRECT: 527 if (log_redirect) { 528 u_long src, dst, gw; 529 530 src = ntohl(ip->ip_src.s_addr); 531 dst = ntohl(icp->icmp_ip.ip_dst.s_addr); 532 gw = ntohl(icp->icmp_gwaddr.s_addr); 533 printf("icmp redirect from %d.%d.%d.%d: " 534 "%d.%d.%d.%d => %d.%d.%d.%d\n", 535 (int)(src >> 24), (int)((src >> 16) & 0xff), 536 (int)((src >> 8) & 0xff), (int)(src & 0xff), 537 (int)(dst >> 24), (int)((dst >> 16) & 0xff), 538 (int)((dst >> 8) & 0xff), (int)(dst & 0xff), 539 (int)(gw >> 24), (int)((gw >> 16) & 0xff), 540 (int)((gw >> 8) & 0xff), (int)(gw & 0xff)); 541 } 542 if (drop_redirect) 543 break; 544 if (code > 3) 545 goto badcode; 546 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 547 IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) { 548 icmpstat.icps_badlen++; 549 break; 550 } 551 /* 552 * Short circuit routing redirects to force 553 * immediate change in the kernel's routing 554 * tables. The message is also handed to anyone 555 * listening on a raw socket (e.g. the routing 556 * daemon for use in updating its tables). 557 */ 558 icmpgw.sin_addr = ip->ip_src; 559 icmpdst.sin_addr = icp->icmp_gwaddr; 560 #ifdef ICMPPRINTFS 561 if (icmpprintfs) { 562 char buf[4 * sizeof "123"]; 563 strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst)); 564 565 printf("redirect dst %s to %s\n", 566 buf, inet_ntoa(icp->icmp_gwaddr)); 567 } 568 #endif 569 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 570 rtredirect((struct sockaddr *)&icmpsrc, 571 (struct sockaddr *)&icmpdst, 572 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 573 (struct sockaddr *)&icmpgw, (struct rtentry **)0); 574 pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc); 575 #ifdef IPSEC 576 key_sa_routechange((struct sockaddr *)&icmpsrc); 577 #endif 578 break; 579 580 /* 581 * No kernel processing for the following; 582 * just fall through to send to raw listener. 583 */ 584 case ICMP_ECHOREPLY: 585 case ICMP_ROUTERADVERT: 586 case ICMP_ROUTERSOLICIT: 587 case ICMP_TSTAMPREPLY: 588 case ICMP_IREQREPLY: 589 case ICMP_MASKREPLY: 590 default: 591 break; 592 } 593 594 raw: 595 rip_input(m, off, proto); 596 return; 597 598 freeit: 599 m_freem(m); 600 } 601 602 /* 603 * Reflect the ip packet back to the source 604 */ 605 static void 606 icmp_reflect(m) 607 struct mbuf *m; 608 { 609 struct ip *ip = mtod(m, struct ip *); 610 struct ifaddr *ifa; 611 struct in_ifaddr *ia; 612 struct in_addr t; 613 struct mbuf *opts = 0; 614 int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip); 615 struct route *ro = NULL, rt; 616 617 if (!in_canforward(ip->ip_src) && 618 ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) != 619 (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 620 m_freem(m); /* Bad return address */ 621 icmpstat.icps_badaddr++; 622 goto done; /* Ip_output() will check for broadcast */ 623 } 624 t = ip->ip_dst; 625 ip->ip_dst = ip->ip_src; 626 ro = &rt; 627 bzero(ro, sizeof(*ro)); 628 /* 629 * If the incoming packet was addressed directly to us, 630 * use dst as the src for the reply. Otherwise (broadcast 631 * or anonymous), use the address which corresponds 632 * to the incoming interface. 633 */ 634 LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) 635 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 636 goto match; 637 if (m->m_pkthdr.rcvif != NULL && 638 m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { 639 TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { 640 if (ifa->ifa_addr->sa_family != AF_INET) 641 continue; 642 ia = ifatoia(ifa); 643 if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr == 644 t.s_addr) 645 goto match; 646 } 647 } 648 ia = ip_rtaddr(ip->ip_dst, ro); 649 /* We need a route to do anything useful. */ 650 if (ia == NULL) { 651 m_freem(m); 652 icmpstat.icps_noroute++; 653 goto done; 654 } 655 match: 656 t = IA_SIN(ia)->sin_addr; 657 ip->ip_src = t; 658 ip->ip_ttl = ip_defttl; 659 660 if (optlen > 0) { 661 u_char *cp; 662 int opt, cnt; 663 u_int len; 664 665 /* 666 * Retrieve any source routing from the incoming packet; 667 * add on any record-route or timestamp options. 668 */ 669 cp = (u_char *) (ip + 1); 670 if ((opts = ip_srcroute()) == 0 && 671 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 672 opts->m_len = sizeof(struct in_addr); 673 mtod(opts, struct in_addr *)->s_addr = 0; 674 } 675 if (opts) { 676 #ifdef ICMPPRINTFS 677 if (icmpprintfs) 678 printf("icmp_reflect optlen %d rt %d => ", 679 optlen, opts->m_len); 680 #endif 681 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 682 opt = cp[IPOPT_OPTVAL]; 683 if (opt == IPOPT_EOL) 684 break; 685 if (opt == IPOPT_NOP) 686 len = 1; 687 else { 688 if (cnt < IPOPT_OLEN + sizeof(*cp)) 689 break; 690 len = cp[IPOPT_OLEN]; 691 if (len < IPOPT_OLEN + sizeof(*cp) || 692 len > cnt) 693 break; 694 } 695 /* 696 * Should check for overflow, but it "can't happen" 697 */ 698 if (opt == IPOPT_RR || opt == IPOPT_TS || 699 opt == IPOPT_SECURITY) { 700 bcopy((caddr_t)cp, 701 mtod(opts, caddr_t) + opts->m_len, len); 702 opts->m_len += len; 703 } 704 } 705 /* Terminate & pad, if necessary */ 706 cnt = opts->m_len % 4; 707 if (cnt) { 708 for (; cnt < 4; cnt++) { 709 *(mtod(opts, caddr_t) + opts->m_len) = 710 IPOPT_EOL; 711 opts->m_len++; 712 } 713 } 714 #ifdef ICMPPRINTFS 715 if (icmpprintfs) 716 printf("%d\n", opts->m_len); 717 #endif 718 } 719 /* 720 * Now strip out original options by copying rest of first 721 * mbuf's data back, and adjust the IP length. 722 */ 723 ip->ip_len -= optlen; 724 ip->ip_vhl = IP_VHL_BORING; 725 m->m_len -= optlen; 726 if (m->m_flags & M_PKTHDR) 727 m->m_pkthdr.len -= optlen; 728 optlen += sizeof(struct ip); 729 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 730 (unsigned)(m->m_len - sizeof(struct ip))); 731 } 732 m->m_flags &= ~(M_BCAST|M_MCAST); 733 icmp_send(m, opts, ro); 734 done: 735 if (opts) 736 (void)m_free(opts); 737 if (ro && ro->ro_rt) 738 RTFREE(ro->ro_rt); 739 } 740 741 /* 742 * Send an icmp packet back to the ip level, 743 * after supplying a checksum. 744 */ 745 static void 746 icmp_send(m, opts, rt) 747 struct mbuf *m; 748 struct mbuf *opts; 749 struct route *rt; 750 { 751 struct ip *ip = mtod(m, struct ip *); 752 int hlen; 753 struct icmp *icp; 754 755 hlen = IP_VHL_HL(ip->ip_vhl) << 2; 756 m->m_data += hlen; 757 m->m_len -= hlen; 758 icp = mtod(m, struct icmp *); 759 icp->icmp_cksum = 0; 760 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 761 m->m_data -= hlen; 762 m->m_len += hlen; 763 m->m_pkthdr.rcvif = (struct ifnet *)0; 764 #ifdef ICMPPRINTFS 765 if (icmpprintfs) { 766 char buf[4 * sizeof "123"]; 767 strcpy(buf, inet_ntoa(ip->ip_dst)); 768 printf("icmp_send dst %s src %s\n", 769 buf, inet_ntoa(ip->ip_src)); 770 } 771 #endif 772 (void) ip_output(m, opts, rt, 0, NULL, NULL); 773 } 774 775 n_time 776 iptime() 777 { 778 struct timeval atv; 779 u_long t; 780 781 getmicrotime(&atv); 782 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 783 return (htonl(t)); 784 } 785 786 #if 1 787 /* 788 * Return the next larger or smaller MTU plateau (table from RFC 1191) 789 * given current value MTU. If DIR is less than zero, a larger plateau 790 * is returned; otherwise, a smaller value is returned. 791 */ 792 static int 793 ip_next_mtu(mtu, dir) 794 int mtu; 795 int dir; 796 { 797 static int mtutab[] = { 798 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296, 799 68, 0 800 }; 801 int i; 802 803 for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) { 804 if (mtu >= mtutab[i]) 805 break; 806 } 807 808 if (dir < 0) { 809 if (i == 0) { 810 return 0; 811 } else { 812 return mtutab[i - 1]; 813 } 814 } else { 815 if (mtutab[i] == 0) { 816 return 0; 817 } else if(mtu > mtutab[i]) { 818 return mtutab[i]; 819 } else { 820 return mtutab[i + 1]; 821 } 822 } 823 } 824 #endif 825 826 #ifdef ICMP_BANDLIM 827 828 /* 829 * badport_bandlim() - check for ICMP bandwidth limit 830 * 831 * Return 0 if it is ok to send an ICMP error response, -1 if we have 832 * hit our bandwidth limit and it is not ok. 833 * 834 * If icmplim is <= 0, the feature is disabled and 0 is returned. 835 * 836 * For now we separate the TCP and UDP subsystems w/ different 'which' 837 * values. We may eventually remove this separation (and simplify the 838 * code further). 839 * 840 * Note that the printing of the error message is delayed so we can 841 * properly print the icmp error rate that the system was trying to do 842 * (i.e. 22000/100 pps, etc...). This can cause long delays in printing 843 * the 'final' error, but it doesn't make sense to solve the printing 844 * delay with more complex code. 845 */ 846 847 int 848 badport_bandlim(int which) 849 { 850 static int lticks[BANDLIM_MAX + 1]; 851 static int lpackets[BANDLIM_MAX + 1]; 852 int dticks; 853 const char *bandlimittype[] = { 854 "Limiting icmp unreach response", 855 "Limiting icmp ping response", 856 "Limiting icmp tstamp response", 857 "Limiting closed port RST response", 858 "Limiting open port RST response" 859 }; 860 861 /* 862 * Return ok status if feature disabled or argument out of 863 * ranage. 864 */ 865 866 if (icmplim <= 0 || which > BANDLIM_MAX || which < 0) 867 return(0); 868 dticks = ticks - lticks[which]; 869 870 /* 871 * reset stats when cumulative dt exceeds one second. 872 */ 873 874 if ((unsigned int)dticks > hz) { 875 if (lpackets[which] > icmplim && icmplim_output) { 876 printf("%s from %d to %d packets per second\n", 877 bandlimittype[which], 878 lpackets[which], 879 icmplim 880 ); 881 } 882 lticks[which] = ticks; 883 lpackets[which] = 0; 884 } 885 886 /* 887 * bump packet count 888 */ 889 890 if (++lpackets[which] > icmplim) { 891 return(-1); 892 } 893 return(0); 894 } 895 896 #endif 897 898 899