ip_icmp.c revision 1.17
1 /* $NetBSD: ip_icmp.c,v 1.17 1995/06/04 05:58:25 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 47 #include <net/if.h> 48 #include <net/route.h> 49 50 #include <netinet/in.h> 51 #include <netinet/in_systm.h> 52 #include <netinet/in_var.h> 53 #include <netinet/ip.h> 54 #include <netinet/ip_icmp.h> 55 #include <netinet/icmp_var.h> 56 57 /* 58 * ICMP routines: error generation, receive packet processing, and 59 * routines to turnaround packets back to the originator, and 60 * host table maintenance routines. 61 */ 62 63 int icmpmaskrepl = 0; 64 #ifdef ICMPPRINTFS 65 int icmpprintfs = 0; 66 #endif 67 68 extern struct protosw inetsw[]; 69 70 /* 71 * Generate an error packet of type error 72 * in response to bad packet ip. 73 */ 74 void 75 icmp_error(n, type, code, dest, destifp) 76 struct mbuf *n; 77 int type, code; 78 n_long dest; 79 struct ifnet *destifp; 80 { 81 register struct ip *oip = mtod(n, struct ip *), *nip; 82 register unsigned oiplen = oip->ip_hl << 2; 83 register struct icmp *icp; 84 register struct mbuf *m; 85 unsigned icmplen; 86 87 #ifdef ICMPPRINTFS 88 if (icmpprintfs) 89 printf("icmp_error(%x, %d, %d)\n", oip, type, code); 90 #endif 91 if (type != ICMP_REDIRECT) 92 icmpstat.icps_error++; 93 /* 94 * Don't send error if not the first fragment of message. 95 * Don't error if the old packet protocol was ICMP 96 * error message, only known informational types. 97 */ 98 if (oip->ip_off &~ (IP_MF|IP_DF)) 99 goto freeit; 100 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 101 n->m_len >= oiplen + ICMP_MINLEN && 102 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 103 icmpstat.icps_oldicmp++; 104 goto freeit; 105 } 106 /* Don't send error in response to a multicast or broadcast packet */ 107 if (n->m_flags & (M_BCAST|M_MCAST)) 108 goto freeit; 109 /* 110 * First, formulate icmp message 111 */ 112 m = m_gethdr(M_DONTWAIT, MT_HEADER); 113 if (m == NULL) 114 goto freeit; 115 icmplen = oiplen + min(8, oip->ip_len); 116 m->m_len = icmplen + ICMP_MINLEN; 117 MH_ALIGN(m, m->m_len); 118 icp = mtod(m, struct icmp *); 119 if ((u_int)type > ICMP_MAXTYPE) 120 panic("icmp_error"); 121 icmpstat.icps_outhist[type]++; 122 icp->icmp_type = type; 123 if (type == ICMP_REDIRECT) 124 icp->icmp_gwaddr.s_addr = dest; 125 else { 126 icp->icmp_void = 0; 127 /* 128 * The following assignments assume an overlay with the 129 * zeroed icmp_void field. 130 */ 131 if (type == ICMP_PARAMPROB) { 132 icp->icmp_pptr = code; 133 code = 0; 134 } else if (type == ICMP_UNREACH && 135 code == ICMP_UNREACH_NEEDFRAG && destifp) 136 icp->icmp_nextmtu = htons(destifp->if_mtu); 137 } 138 139 icp->icmp_code = code; 140 bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen); 141 nip = &icp->icmp_ip; 142 nip->ip_len = htons((u_int16_t)(nip->ip_len + oiplen)); 143 144 /* 145 * Now, copy old ip header (without options) 146 * in front of icmp message. 147 */ 148 if (m->m_data - sizeof(struct ip) < m->m_pktdat) 149 panic("icmp len"); 150 m->m_data -= sizeof(struct ip); 151 m->m_len += sizeof(struct ip); 152 m->m_pkthdr.len = m->m_len; 153 m->m_pkthdr.rcvif = n->m_pkthdr.rcvif; 154 nip = mtod(m, struct ip *); 155 bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip)); 156 nip->ip_len = m->m_len; 157 nip->ip_hl = sizeof(struct ip) >> 2; 158 nip->ip_p = IPPROTO_ICMP; 159 nip->ip_tos = 0; 160 icmp_reflect(m); 161 162 freeit: 163 m_freem(n); 164 } 165 166 static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET }; 167 static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET }; 168 static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET }; 169 struct sockaddr_in icmpmask = { 8, 0 }; 170 171 /* 172 * Process a received ICMP message. 173 */ 174 void 175 icmp_input(m, hlen) 176 register struct mbuf *m; 177 int hlen; 178 { 179 register struct icmp *icp; 180 register struct ip *ip = mtod(m, struct ip *); 181 int icmplen = ip->ip_len; 182 register int i; 183 struct in_ifaddr *ia; 184 void (*ctlfunc) __P((int, struct sockaddr *, struct ip *)); 185 int code; 186 extern u_char ip_protox[]; 187 188 /* 189 * Locate icmp structure in mbuf, and check 190 * that not corrupted and of at least minimum length. 191 */ 192 #ifdef ICMPPRINTFS 193 if (icmpprintfs) 194 printf("icmp_input from %x to %x, len %d\n", 195 ntohl(ip->ip_src.s_addr), ntohl(ip->ip_dst.s_addr), 196 icmplen); 197 #endif 198 if (icmplen < ICMP_MINLEN) { 199 icmpstat.icps_tooshort++; 200 goto freeit; 201 } 202 i = hlen + min(icmplen, ICMP_ADVLENMIN); 203 if (m->m_len < i && (m = m_pullup(m, i)) == 0) { 204 icmpstat.icps_tooshort++; 205 return; 206 } 207 ip = mtod(m, struct ip *); 208 m->m_len -= hlen; 209 m->m_data += hlen; 210 icp = mtod(m, struct icmp *); 211 if (in_cksum(m, icmplen)) { 212 icmpstat.icps_checksum++; 213 goto freeit; 214 } 215 m->m_len += hlen; 216 m->m_data -= hlen; 217 218 #ifdef ICMPPRINTFS 219 /* 220 * Message type specific processing. 221 */ 222 if (icmpprintfs) 223 printf("icmp_input, type %d code %d\n", icp->icmp_type, 224 icp->icmp_code); 225 #endif 226 if (icp->icmp_type > ICMP_MAXTYPE) 227 goto raw; 228 icmpstat.icps_inhist[icp->icmp_type]++; 229 code = icp->icmp_code; 230 switch (icp->icmp_type) { 231 232 case ICMP_UNREACH: 233 switch (code) { 234 case ICMP_UNREACH_NET: 235 case ICMP_UNREACH_HOST: 236 case ICMP_UNREACH_PROTOCOL: 237 case ICMP_UNREACH_PORT: 238 case ICMP_UNREACH_SRCFAIL: 239 code += PRC_UNREACH_NET; 240 break; 241 242 case ICMP_UNREACH_NEEDFRAG: 243 code = PRC_MSGSIZE; 244 break; 245 246 case ICMP_UNREACH_NET_UNKNOWN: 247 case ICMP_UNREACH_NET_PROHIB: 248 case ICMP_UNREACH_TOSNET: 249 code = PRC_UNREACH_NET; 250 break; 251 252 case ICMP_UNREACH_HOST_UNKNOWN: 253 case ICMP_UNREACH_ISOLATED: 254 case ICMP_UNREACH_HOST_PROHIB: 255 case ICMP_UNREACH_TOSHOST: 256 code = PRC_UNREACH_HOST; 257 break; 258 259 default: 260 goto badcode; 261 } 262 goto deliver; 263 264 case ICMP_TIMXCEED: 265 if (code > 1) 266 goto badcode; 267 code += PRC_TIMXCEED_INTRANS; 268 goto deliver; 269 270 case ICMP_PARAMPROB: 271 if (code > 1) 272 goto badcode; 273 code = PRC_PARAMPROB; 274 goto deliver; 275 276 case ICMP_SOURCEQUENCH: 277 if (code) 278 goto badcode; 279 code = PRC_QUENCH; 280 deliver: 281 /* 282 * Problem with datagram; advise higher level routines. 283 */ 284 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 285 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 286 icmpstat.icps_badlen++; 287 goto freeit; 288 } 289 if (IN_MULTICAST(icp->icmp_ip.ip_dst.s_addr)) 290 goto badcode; 291 NTOHS(icp->icmp_ip.ip_len); 292 #ifdef ICMPPRINTFS 293 if (icmpprintfs) 294 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 295 #endif 296 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 297 if (ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput) 298 (*ctlfunc)(code, sintosa(&icmpsrc), &icp->icmp_ip); 299 break; 300 301 badcode: 302 icmpstat.icps_badcode++; 303 break; 304 305 case ICMP_ECHO: 306 icp->icmp_type = ICMP_ECHOREPLY; 307 goto reflect; 308 309 case ICMP_TSTAMP: 310 if (icmplen < ICMP_TSLEN) { 311 icmpstat.icps_badlen++; 312 break; 313 } 314 icp->icmp_type = ICMP_TSTAMPREPLY; 315 icp->icmp_rtime = iptime(); 316 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 317 goto reflect; 318 319 case ICMP_MASKREQ: 320 if (icmpmaskrepl == 0) 321 break; 322 /* 323 * We are not able to respond with all ones broadcast 324 * unless we receive it over a point-to-point interface. 325 */ 326 if (icmplen < ICMP_MASKLEN) 327 break; 328 if (ip->ip_dst.s_addr == INADDR_BROADCAST || 329 ip->ip_dst.s_addr == INADDR_ANY) 330 icmpdst.sin_addr = ip->ip_src; 331 else 332 icmpdst.sin_addr = ip->ip_dst; 333 ia = ifatoia(ifaof_ifpforaddr(sintosa(&icmpdst), 334 m->m_pkthdr.rcvif)); 335 if (ia == 0) 336 break; 337 icp->icmp_type = ICMP_MASKREPLY; 338 icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; 339 if (ip->ip_src.s_addr == 0) { 340 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 341 ip->ip_src = ia->ia_broadaddr.sin_addr; 342 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 343 ip->ip_src = ia->ia_dstaddr.sin_addr; 344 } 345 reflect: 346 ip->ip_len += hlen; /* since ip_input deducts this */ 347 icmpstat.icps_reflect++; 348 icmpstat.icps_outhist[icp->icmp_type]++; 349 icmp_reflect(m); 350 return; 351 352 case ICMP_REDIRECT: 353 if (code > 3) 354 goto badcode; 355 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) || 356 icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) { 357 icmpstat.icps_badlen++; 358 break; 359 } 360 /* 361 * Short circuit routing redirects to force 362 * immediate change in the kernel's routing 363 * tables. The message is also handed to anyone 364 * listening on a raw socket (e.g. the routing 365 * daemon for use in updating its tables). 366 */ 367 icmpgw.sin_addr = ip->ip_src; 368 icmpdst.sin_addr = icp->icmp_gwaddr; 369 #ifdef ICMPPRINTFS 370 if (icmpprintfs) 371 printf("redirect dst %x to %x\n", icp->icmp_ip.ip_dst, 372 icp->icmp_gwaddr); 373 #endif 374 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 375 rtredirect(sintosa(&icmpsrc), sintosa(&icmpdst), 376 (struct sockaddr *)0, RTF_GATEWAY | RTF_HOST, 377 sintosa(&icmpgw), (struct rtentry **)0); 378 pfctlinput(PRC_REDIRECT_HOST, sintosa(&icmpsrc)); 379 break; 380 381 /* 382 * No kernel processing for the following; 383 * just fall through to send to raw listener. 384 */ 385 case ICMP_ECHOREPLY: 386 case ICMP_ROUTERADVERT: 387 case ICMP_ROUTERSOLICIT: 388 case ICMP_TSTAMPREPLY: 389 case ICMP_IREQREPLY: 390 case ICMP_MASKREPLY: 391 default: 392 break; 393 } 394 395 raw: 396 rip_input(m); 397 return; 398 399 freeit: 400 m_freem(m); 401 } 402 403 /* 404 * Reflect the ip packet back to the source 405 */ 406 void 407 icmp_reflect(m) 408 struct mbuf *m; 409 { 410 register struct ip *ip = mtod(m, struct ip *); 411 register struct in_ifaddr *ia; 412 struct in_addr t; 413 struct mbuf *opts = 0, *ip_srcroute(); 414 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 415 416 if (!in_canforward(ip->ip_src) && 417 ((ip->ip_src.s_addr & IN_CLASSA_NET) != 418 htonl(IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) { 419 m_freem(m); /* Bad return address */ 420 goto done; /* ip_output() will check for broadcast */ 421 } 422 t = ip->ip_dst; 423 ip->ip_dst = ip->ip_src; 424 /* 425 * If the incoming packet was addressed directly to us, 426 * use dst as the src for the reply. Otherwise (broadcast 427 * or anonymous), use the address which corresponds 428 * to the incoming interface. 429 */ 430 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 431 if (t.s_addr == ia->ia_addr.sin_addr.s_addr) 432 break; 433 if ((ia->ia_ifp->if_flags & IFF_BROADCAST) && 434 t.s_addr == ia->ia_broadaddr.sin_addr.s_addr) 435 break; 436 } 437 icmpdst.sin_addr = t; 438 if (ia == (struct in_ifaddr *)0) 439 ia = ifatoia(ifaof_ifpforaddr(sintosa(&icmpdst), 440 m->m_pkthdr.rcvif)); 441 /* 442 * The following happens if the packet was not addressed to us, 443 * and was received on an interface with no IP address. 444 */ 445 if (ia == (struct in_ifaddr *)0) 446 ia = in_ifaddr; 447 t = ia->ia_addr.sin_addr; 448 ip->ip_src = t; 449 ip->ip_ttl = MAXTTL; 450 451 if (optlen > 0) { 452 register u_char *cp; 453 int opt, cnt; 454 u_int len; 455 456 /* 457 * Retrieve any source routing from the incoming packet; 458 * add on any record-route or timestamp options. 459 */ 460 cp = (u_char *) (ip + 1); 461 if ((opts = ip_srcroute()) == 0 && 462 (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { 463 opts->m_len = sizeof(struct in_addr); 464 mtod(opts, struct in_addr *)->s_addr = 0; 465 } 466 if (opts) { 467 #ifdef ICMPPRINTFS 468 if (icmpprintfs) 469 printf("icmp_reflect optlen %d rt %d => ", 470 optlen, opts->m_len); 471 #endif 472 for (cnt = optlen; cnt > 0; cnt -= len, cp += len) { 473 opt = cp[IPOPT_OPTVAL]; 474 if (opt == IPOPT_EOL) 475 break; 476 if (opt == IPOPT_NOP) 477 len = 1; 478 else { 479 len = cp[IPOPT_OLEN]; 480 if (len <= 0 || len > cnt) 481 break; 482 } 483 /* 484 * Should check for overflow, but it "can't happen" 485 */ 486 if (opt == IPOPT_RR || opt == IPOPT_TS || 487 opt == IPOPT_SECURITY) { 488 bcopy((caddr_t)cp, 489 mtod(opts, caddr_t) + opts->m_len, len); 490 opts->m_len += len; 491 } 492 } 493 /* Terminate & pad, if necessary */ 494 if (cnt = opts->m_len % 4) { 495 for (; cnt < 4; cnt++) { 496 *(mtod(opts, caddr_t) + opts->m_len) = 497 IPOPT_EOL; 498 opts->m_len++; 499 } 500 } 501 #ifdef ICMPPRINTFS 502 if (icmpprintfs) 503 printf("%d\n", opts->m_len); 504 #endif 505 } 506 /* 507 * Now strip out original options by copying rest of first 508 * mbuf's data back, and adjust the IP length. 509 */ 510 ip->ip_len -= optlen; 511 ip->ip_hl = sizeof(struct ip) >> 2; 512 m->m_len -= optlen; 513 if (m->m_flags & M_PKTHDR) 514 m->m_pkthdr.len -= optlen; 515 optlen += sizeof(struct ip); 516 bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1), 517 (unsigned)(m->m_len - sizeof(struct ip))); 518 } 519 m->m_flags &= ~(M_BCAST|M_MCAST); 520 icmp_send(m, opts); 521 done: 522 if (opts) 523 (void)m_free(opts); 524 } 525 526 /* 527 * Send an icmp packet back to the ip level, 528 * after supplying a checksum. 529 */ 530 void 531 icmp_send(m, opts) 532 register struct mbuf *m; 533 struct mbuf *opts; 534 { 535 register struct ip *ip = mtod(m, struct ip *); 536 register int hlen; 537 register struct icmp *icp; 538 539 hlen = ip->ip_hl << 2; 540 m->m_data += hlen; 541 m->m_len -= hlen; 542 icp = mtod(m, struct icmp *); 543 icp->icmp_cksum = 0; 544 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 545 m->m_data -= hlen; 546 m->m_len += hlen; 547 #ifdef ICMPPRINTFS 548 if (icmpprintfs) 549 printf("icmp_send dst %x src %x\n", ip->ip_dst, ip->ip_src); 550 #endif 551 (void) ip_output(m, opts, NULL, 0, NULL); 552 } 553 554 n_time 555 iptime() 556 { 557 struct timeval atv; 558 u_long t; 559 560 microtime(&atv); 561 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 562 return (htonl(t)); 563 } 564 565 int 566 icmp_sysctl(name, namelen, oldp, oldlenp, newp, newlen) 567 int *name; 568 u_int namelen; 569 void *oldp; 570 size_t *oldlenp; 571 void *newp; 572 size_t newlen; 573 { 574 575 /* All sysctl names at this level are terminal. */ 576 if (namelen != 1) 577 return (ENOTDIR); 578 579 switch (name[0]) { 580 case ICMPCTL_MASKREPL: 581 return (sysctl_int(oldp, oldlenp, newp, newlen, &icmpmaskrepl)); 582 default: 583 return (ENOPROTOOPT); 584 } 585 /* NOTREACHED */ 586 } 587
Indexes created Thu Sep 25 16:09:42 GMT 2025