1 /* 2 * Copyright (c) 1982, 1986 Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms are permitted 6 * provided that the above copyright notice and this paragraph are 7 * duplicated in all such forms and that any documentation, 8 * advertising materials, and other materials related to such 9 * distribution and use acknowledge that the software was developed 10 * by the University of California, Berkeley. The name of the 11 * University may not be used to endorse or promote products derived 12 * from this software without specific prior written permission. 13 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 15 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 16 * 17 * @(#)ip_icmp.c 7.8 (Berkeley) 06/29/88 18 */ 19 20 #include "param.h" 21 #include "systm.h" 22 #include "mbuf.h" 23 #include "protosw.h" 24 #include "socket.h" 25 #include "time.h" 26 #include "kernel.h" 27 28 #include "../net/route.h" 29 #include "../net/if.h" 30 31 #include "in.h" 32 #include "in_systm.h" 33 #include "in_var.h" 34 #include "ip.h" 35 #include "ip_icmp.h" 36 #include "icmp_var.h" 37 38 #ifdef ICMPPRINTFS 39 /* 40 * ICMP routines: error generation, receive packet processing, and 41 * routines to turnaround packets back to the originator, and 42 * host table maintenance routines. 43 */ 44 int icmpprintfs = 0; 45 #endif 46 47 /* 48 * Generate an error packet of type error 49 * in response to bad packet ip. 50 */ 51 /*VARARGS4*/ 52 icmp_error(oip, type, code, ifp, dest) 53 struct ip *oip; 54 int type, code; 55 struct ifnet *ifp; 56 struct in_addr dest; 57 { 58 register unsigned oiplen = oip->ip_hl << 2; 59 register struct icmp *icp; 60 struct mbuf *m; 61 struct ip *nip; 62 unsigned icmplen; 63 64 #ifdef ICMPPRINTFS 65 if (icmpprintfs) 66 printf("icmp_error(%x, %d, %d)\n", oip, type, code); 67 #endif 68 if (type != ICMP_REDIRECT) 69 icmpstat.icps_error++; 70 /* 71 * Don't send error if not the first fragment of message. 72 * Don't error if the old packet protocol was ICMP 73 * error message, only known informational types. 74 */ 75 if (oip->ip_off &~ (IP_MF|IP_DF)) 76 goto free; 77 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 78 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 79 icmpstat.icps_oldicmp++; 80 goto free; 81 } 82 83 /* 84 * First, formulate icmp message 85 */ 86 m = m_get(M_DONTWAIT, MT_HEADER); 87 if (m == NULL) 88 goto free; 89 icmplen = oiplen + MIN(8, oip->ip_len); 90 m->m_len = icmplen + ICMP_MINLEN; 91 m->m_off = MMAXOFF - m->m_len; 92 icp = mtod(m, struct icmp *); 93 if ((u_int)type > ICMP_MAXTYPE) 94 panic("icmp_error"); 95 icmpstat.icps_outhist[type]++; 96 icp->icmp_type = type; 97 if (type == ICMP_REDIRECT) 98 icp->icmp_gwaddr = dest; 99 else 100 icp->icmp_void = 0; 101 if (type == ICMP_PARAMPROB) { 102 icp->icmp_pptr = code; 103 code = 0; 104 } 105 icp->icmp_code = code; 106 bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen); 107 nip = &icp->icmp_ip; 108 nip->ip_len += oiplen; 109 nip->ip_len = htons((u_short)nip->ip_len); 110 111 /* 112 * Now, copy old ip header in front of icmp message. 113 */ 114 if (m->m_len + oiplen > MLEN) 115 oiplen = sizeof(struct ip); 116 if (m->m_len + oiplen > MLEN) 117 panic("icmp len"); 118 m->m_off -= oiplen; 119 m->m_len += oiplen; 120 nip = mtod(m, struct ip *); 121 bcopy((caddr_t)oip, (caddr_t)nip, oiplen); 122 nip->ip_len = m->m_len; 123 nip->ip_p = IPPROTO_ICMP; 124 icmp_reflect(nip, ifp); 125 126 free: 127 m_freem(dtom(oip)); 128 } 129 130 static struct sockproto icmproto = { AF_INET, IPPROTO_ICMP }; 131 static struct sockaddr_in icmpsrc = { AF_INET }; 132 static struct sockaddr_in icmpdst = { AF_INET }; 133 static struct sockaddr_in icmpgw = { AF_INET }; 134 struct in_ifaddr *ifptoia(); 135 136 /* 137 * Process a received ICMP message. 138 */ 139 icmp_input(m, ifp) 140 register struct mbuf *m; 141 struct ifnet *ifp; 142 { 143 register struct icmp *icp; 144 register struct ip *ip = mtod(m, struct ip *); 145 int icmplen = ip->ip_len, hlen = ip->ip_hl << 2; 146 register int i; 147 struct in_ifaddr *ia; 148 int (*ctlfunc)(), code; 149 extern u_char ip_protox[]; 150 extern struct in_addr in_makeaddr(); 151 152 /* 153 * Locate icmp structure in mbuf, and check 154 * that not corrupted and of at least minimum length. 155 */ 156 #ifdef ICMPPRINTFS 157 if (icmpprintfs) 158 printf("icmp_input from %x, len %d\n", ip->ip_src, icmplen); 159 #endif 160 if (icmplen < ICMP_MINLEN) { 161 icmpstat.icps_tooshort++; 162 goto free; 163 } 164 i = hlen + MIN(icmplen, ICMP_ADVLENMIN); 165 if ((m->m_off > MMAXOFF || m->m_len < i) && 166 (m = m_pullup(m, i)) == 0) { 167 icmpstat.icps_tooshort++; 168 return; 169 } 170 ip = mtod(m, struct ip *); 171 m->m_len -= hlen; 172 m->m_off += hlen; 173 icp = mtod(m, struct icmp *); 174 if (in_cksum(m, icmplen)) { 175 icmpstat.icps_checksum++; 176 goto free; 177 } 178 m->m_len += hlen; 179 m->m_off -= hlen; 180 181 #ifdef ICMPPRINTFS 182 /* 183 * Message type specific processing. 184 */ 185 if (icmpprintfs) 186 printf("icmp_input, type %d code %d\n", icp->icmp_type, 187 icp->icmp_code); 188 #endif 189 if (icp->icmp_type > ICMP_MAXTYPE) 190 goto raw; 191 icmpstat.icps_inhist[icp->icmp_type]++; 192 code = icp->icmp_code; 193 switch (icp->icmp_type) { 194 195 case ICMP_UNREACH: 196 if (code > 5) 197 goto badcode; 198 code += PRC_UNREACH_NET; 199 goto deliver; 200 201 case ICMP_TIMXCEED: 202 if (code > 1) 203 goto badcode; 204 code += PRC_TIMXCEED_INTRANS; 205 goto deliver; 206 207 case ICMP_PARAMPROB: 208 if (code) 209 goto badcode; 210 code = PRC_PARAMPROB; 211 goto deliver; 212 213 case ICMP_SOURCEQUENCH: 214 if (code) 215 goto badcode; 216 code = PRC_QUENCH; 217 deliver: 218 /* 219 * Problem with datagram; advise higher level routines. 220 */ 221 icp->icmp_ip.ip_len = ntohs((u_short)icp->icmp_ip.ip_len); 222 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)) { 223 icmpstat.icps_badlen++; 224 goto free; 225 } 226 #ifdef ICMPPRINTFS 227 if (icmpprintfs) 228 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 229 #endif 230 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 231 if (ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput) 232 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc); 233 break; 234 235 badcode: 236 icmpstat.icps_badcode++; 237 break; 238 239 case ICMP_ECHO: 240 icp->icmp_type = ICMP_ECHOREPLY; 241 goto reflect; 242 243 case ICMP_TSTAMP: 244 if (icmplen < ICMP_TSLEN) { 245 icmpstat.icps_badlen++; 246 break; 247 } 248 icp->icmp_type = ICMP_TSTAMPREPLY; 249 icp->icmp_rtime = iptime(); 250 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 251 goto reflect; 252 253 case ICMP_IREQ: 254 #define satosin(sa) ((struct sockaddr_in *)(sa)) 255 if (in_netof(ip->ip_src) == 0 && (ia = ifptoia(ifp))) 256 ip->ip_src = in_makeaddr(in_netof(IA_SIN(ia)->sin_addr), 257 in_lnaof(ip->ip_src)); 258 icp->icmp_type = ICMP_IREQREPLY; 259 goto reflect; 260 261 case ICMP_MASKREQ: 262 if (icmplen < ICMP_MASKLEN || (ia = ifptoia(ifp)) == 0) 263 break; 264 icp->icmp_type = ICMP_MASKREPLY; 265 icp->icmp_mask = htonl(ia->ia_subnetmask); 266 if (ip->ip_src.s_addr == 0) { 267 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 268 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 269 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 270 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 271 } 272 reflect: 273 ip->ip_len += hlen; /* since ip_input deducts this */ 274 icmpstat.icps_reflect++; 275 icmpstat.icps_outhist[icp->icmp_type]++; 276 icmp_reflect(ip, ifp); 277 return; 278 279 case ICMP_REDIRECT: 280 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)) { 281 icmpstat.icps_badlen++; 282 break; 283 } 284 /* 285 * Short circuit routing redirects to force 286 * immediate change in the kernel's routing 287 * tables. The message is also handed to anyone 288 * listening on a raw socket (e.g. the routing 289 * daemon for use in updating its tables). 290 */ 291 icmpgw.sin_addr = ip->ip_src; 292 icmpdst.sin_addr = icp->icmp_gwaddr; 293 #ifdef ICMPPRINTFS 294 if (icmpprintfs) 295 printf("redirect dst %x to %x\n", icp->icmp_ip.ip_dst, 296 icp->icmp_gwaddr); 297 #endif 298 if (code == ICMP_REDIRECT_NET || code == ICMP_REDIRECT_TOSNET) { 299 icmpsrc.sin_addr = 300 in_makeaddr(in_netof(icp->icmp_ip.ip_dst), INADDR_ANY); 301 rtredirect((struct sockaddr *)&icmpsrc, 302 (struct sockaddr *)&icmpdst, RTF_GATEWAY, 303 (struct sockaddr *)&icmpgw); 304 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 305 pfctlinput(PRC_REDIRECT_NET, 306 (struct sockaddr *)&icmpsrc); 307 } else { 308 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 309 rtredirect((struct sockaddr *)&icmpsrc, 310 (struct sockaddr *)&icmpdst, RTF_GATEWAY | RTF_HOST, 311 (struct sockaddr *)&icmpgw); 312 pfctlinput(PRC_REDIRECT_HOST, 313 (struct sockaddr *)&icmpsrc); 314 } 315 break; 316 317 /* 318 * No kernel processing for the following; 319 * just fall through to send to raw listener. 320 */ 321 case ICMP_ECHOREPLY: 322 case ICMP_TSTAMPREPLY: 323 case ICMP_IREQREPLY: 324 case ICMP_MASKREPLY: 325 default: 326 break; 327 } 328 329 raw: 330 icmpsrc.sin_addr = ip->ip_src; 331 icmpdst.sin_addr = ip->ip_dst; 332 raw_input(m, &icmproto, (struct sockaddr *)&icmpsrc, 333 (struct sockaddr *)&icmpdst); 334 return; 335 336 free: 337 m_freem(m); 338 } 339 340 /* 341 * Reflect the ip packet back to the source 342 */ 343 icmp_reflect(ip, ifp) 344 register struct ip *ip; 345 struct ifnet *ifp; 346 { 347 register struct in_ifaddr *ia; 348 struct in_addr t; 349 struct mbuf *opts = 0, *ip_srcroute(); 350 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 351 352 t = ip->ip_dst; 353 ip->ip_dst = ip->ip_src; 354 /* 355 * If the incoming packet was addressed directly to us, 356 * use dst as the src for the reply. Otherwise (broadcast 357 * or anonymous), use the address which corresponds 358 * to the incoming interface. 359 */ 360 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 361 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 362 break; 363 if ((ia->ia_ifp->if_flags & IFF_BROADCAST) && 364 t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr) 365 break; 366 } 367 if (ia == (struct in_ifaddr *)0) 368 ia = ifptoia(ifp); 369 if (ia == (struct in_ifaddr *)0) 370 ia = in_ifaddr; 371 t = IA_SIN(ia)->sin_addr; 372 ip->ip_src = t; 373 ip->ip_ttl = MAXTTL; 374 375 if (optlen > 0) { 376 /* 377 * Retrieve any source routing from the incoming packet 378 * and strip out other options. Adjust the IP length. 379 */ 380 opts = ip_srcroute(); 381 ip->ip_len -= optlen; 382 ip_stripoptions(ip, (struct mbuf *)0); 383 } 384 icmp_send(ip, opts); 385 if (opts) 386 (void)m_free(opts); 387 } 388 389 struct in_ifaddr * 390 ifptoia(ifp) 391 struct ifnet *ifp; 392 { 393 register struct in_ifaddr *ia; 394 395 for (ia = in_ifaddr; ia; ia = ia->ia_next) 396 if (ia->ia_ifp == ifp) 397 return (ia); 398 return ((struct in_ifaddr *)0); 399 } 400 401 /* 402 * Send an icmp packet back to the ip level, 403 * after supplying a checksum. 404 */ 405 icmp_send(ip, opts) 406 register struct ip *ip; 407 struct mbuf *opts; 408 { 409 register int hlen; 410 register struct icmp *icp; 411 register struct mbuf *m; 412 413 m = dtom(ip); 414 hlen = ip->ip_hl << 2; 415 m->m_off += hlen; 416 m->m_len -= hlen; 417 icp = mtod(m, struct icmp *); 418 icp->icmp_cksum = 0; 419 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 420 m->m_off -= hlen; 421 m->m_len += hlen; 422 #ifdef ICMPPRINTFS 423 if (icmpprintfs) 424 printf("icmp_send dst %x src %x\n", ip->ip_dst, ip->ip_src); 425 #endif 426 (void) ip_output(m, opts, (struct route *)0, 0); 427 } 428 429 n_time 430 iptime() 431 { 432 struct timeval atv; 433 u_long t; 434 435 microtime(&atv); 436 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 437 return (htonl(t)); 438 } 439