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 this notice is preserved and that due credit is given 7 * to the University of California at Berkeley. The name of the University 8 * may not be used to endorse or promote products derived from this 9 * software without specific prior written permission. This software 10 * is provided ``as is'' without express or implied warranty. 11 * 12 * @(#)ip_icmp.c 7.7 (Berkeley) 12/07/87 13 */ 14 15 #include "param.h" 16 #include "systm.h" 17 #include "mbuf.h" 18 #include "protosw.h" 19 #include "socket.h" 20 #include "time.h" 21 #include "kernel.h" 22 23 #include "../net/route.h" 24 #include "../net/if.h" 25 26 #include "in.h" 27 #include "in_systm.h" 28 #include "in_var.h" 29 #include "ip.h" 30 #include "ip_icmp.h" 31 #include "icmp_var.h" 32 33 #ifdef ICMPPRINTFS 34 /* 35 * ICMP routines: error generation, receive packet processing, and 36 * routines to turnaround packets back to the originator, and 37 * host table maintenance routines. 38 */ 39 int icmpprintfs = 0; 40 #endif 41 42 /* 43 * Generate an error packet of type error 44 * in response to bad packet ip. 45 */ 46 /*VARARGS4*/ 47 icmp_error(oip, type, code, ifp, dest) 48 struct ip *oip; 49 int type, code; 50 struct ifnet *ifp; 51 struct in_addr dest; 52 { 53 register unsigned oiplen = oip->ip_hl << 2; 54 register struct icmp *icp; 55 struct mbuf *m; 56 struct ip *nip; 57 unsigned icmplen; 58 59 #ifdef ICMPPRINTFS 60 if (icmpprintfs) 61 printf("icmp_error(%x, %d, %d)\n", oip, type, code); 62 #endif 63 if (type != ICMP_REDIRECT) 64 icmpstat.icps_error++; 65 /* 66 * Don't send error if not the first fragment of message. 67 * Don't error if the old packet protocol was ICMP 68 * error message, only known informational types. 69 */ 70 if (oip->ip_off &~ (IP_MF|IP_DF)) 71 goto free; 72 if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && 73 !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiplen))->icmp_type)) { 74 icmpstat.icps_oldicmp++; 75 goto free; 76 } 77 78 /* 79 * First, formulate icmp message 80 */ 81 m = m_get(M_DONTWAIT, MT_HEADER); 82 if (m == NULL) 83 goto free; 84 icmplen = oiplen + MIN(8, oip->ip_len); 85 m->m_len = icmplen + ICMP_MINLEN; 86 m->m_off = MMAXOFF - m->m_len; 87 icp = mtod(m, struct icmp *); 88 if ((u_int)type > ICMP_MAXTYPE) 89 panic("icmp_error"); 90 icmpstat.icps_outhist[type]++; 91 icp->icmp_type = type; 92 if (type == ICMP_REDIRECT) 93 icp->icmp_gwaddr = dest; 94 else 95 icp->icmp_void = 0; 96 if (type == ICMP_PARAMPROB) { 97 icp->icmp_pptr = code; 98 code = 0; 99 } 100 icp->icmp_code = code; 101 bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen); 102 nip = &icp->icmp_ip; 103 nip->ip_len += oiplen; 104 nip->ip_len = htons((u_short)nip->ip_len); 105 106 /* 107 * Now, copy old ip header in front of icmp message. 108 */ 109 if (m->m_len + oiplen > MLEN) 110 oiplen = sizeof(struct ip); 111 if (m->m_len + oiplen > MLEN) 112 panic("icmp len"); 113 m->m_off -= oiplen; 114 m->m_len += oiplen; 115 nip = mtod(m, struct ip *); 116 bcopy((caddr_t)oip, (caddr_t)nip, oiplen); 117 nip->ip_len = m->m_len; 118 nip->ip_p = IPPROTO_ICMP; 119 icmp_reflect(nip, ifp); 120 121 free: 122 m_freem(dtom(oip)); 123 } 124 125 static struct sockproto icmproto = { AF_INET, IPPROTO_ICMP }; 126 static struct sockaddr_in icmpsrc = { AF_INET }; 127 static struct sockaddr_in icmpdst = { AF_INET }; 128 static struct sockaddr_in icmpgw = { AF_INET }; 129 struct in_ifaddr *ifptoia(); 130 131 /* 132 * Process a received ICMP message. 133 */ 134 icmp_input(m, ifp) 135 register struct mbuf *m; 136 struct ifnet *ifp; 137 { 138 register struct icmp *icp; 139 register struct ip *ip = mtod(m, struct ip *); 140 int icmplen = ip->ip_len, hlen = ip->ip_hl << 2; 141 register int i; 142 struct in_ifaddr *ia; 143 int (*ctlfunc)(), code; 144 extern u_char ip_protox[]; 145 extern struct in_addr in_makeaddr(); 146 147 /* 148 * Locate icmp structure in mbuf, and check 149 * that not corrupted and of at least minimum length. 150 */ 151 #ifdef ICMPPRINTFS 152 if (icmpprintfs) 153 printf("icmp_input from %x, len %d\n", ip->ip_src, icmplen); 154 #endif 155 if (icmplen < ICMP_MINLEN) { 156 icmpstat.icps_tooshort++; 157 goto free; 158 } 159 i = hlen + MIN(icmplen, ICMP_ADVLENMIN); 160 if ((m->m_off > MMAXOFF || m->m_len < i) && 161 (m = m_pullup(m, i)) == 0) { 162 icmpstat.icps_tooshort++; 163 return; 164 } 165 ip = mtod(m, struct ip *); 166 m->m_len -= hlen; 167 m->m_off += hlen; 168 icp = mtod(m, struct icmp *); 169 if (in_cksum(m, icmplen)) { 170 icmpstat.icps_checksum++; 171 goto free; 172 } 173 m->m_len += hlen; 174 m->m_off -= hlen; 175 176 #ifdef ICMPPRINTFS 177 /* 178 * Message type specific processing. 179 */ 180 if (icmpprintfs) 181 printf("icmp_input, type %d code %d\n", icp->icmp_type, 182 icp->icmp_code); 183 #endif 184 if (icp->icmp_type > ICMP_MAXTYPE) 185 goto raw; 186 icmpstat.icps_inhist[icp->icmp_type]++; 187 code = icp->icmp_code; 188 switch (icp->icmp_type) { 189 190 case ICMP_UNREACH: 191 if (code > 5) 192 goto badcode; 193 code += PRC_UNREACH_NET; 194 goto deliver; 195 196 case ICMP_TIMXCEED: 197 if (code > 1) 198 goto badcode; 199 code += PRC_TIMXCEED_INTRANS; 200 goto deliver; 201 202 case ICMP_PARAMPROB: 203 if (code) 204 goto badcode; 205 code = PRC_PARAMPROB; 206 goto deliver; 207 208 case ICMP_SOURCEQUENCH: 209 if (code) 210 goto badcode; 211 code = PRC_QUENCH; 212 deliver: 213 /* 214 * Problem with datagram; advise higher level routines. 215 */ 216 icp->icmp_ip.ip_len = ntohs((u_short)icp->icmp_ip.ip_len); 217 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)) { 218 icmpstat.icps_badlen++; 219 goto free; 220 } 221 #ifdef ICMPPRINTFS 222 if (icmpprintfs) 223 printf("deliver to protocol %d\n", icp->icmp_ip.ip_p); 224 #endif 225 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 226 if (ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput) 227 (*ctlfunc)(code, (struct sockaddr *)&icmpsrc); 228 break; 229 230 badcode: 231 icmpstat.icps_badcode++; 232 break; 233 234 case ICMP_ECHO: 235 icp->icmp_type = ICMP_ECHOREPLY; 236 goto reflect; 237 238 case ICMP_TSTAMP: 239 if (icmplen < ICMP_TSLEN) { 240 icmpstat.icps_badlen++; 241 break; 242 } 243 icp->icmp_type = ICMP_TSTAMPREPLY; 244 icp->icmp_rtime = iptime(); 245 icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */ 246 goto reflect; 247 248 case ICMP_IREQ: 249 #define satosin(sa) ((struct sockaddr_in *)(sa)) 250 if (in_netof(ip->ip_src) == 0 && (ia = ifptoia(ifp))) 251 ip->ip_src = in_makeaddr(in_netof(IA_SIN(ia)->sin_addr), 252 in_lnaof(ip->ip_src)); 253 icp->icmp_type = ICMP_IREQREPLY; 254 goto reflect; 255 256 case ICMP_MASKREQ: 257 if (icmplen < ICMP_MASKLEN || (ia = ifptoia(ifp)) == 0) 258 break; 259 icp->icmp_type = ICMP_MASKREPLY; 260 icp->icmp_mask = htonl(ia->ia_subnetmask); 261 if (ip->ip_src.s_addr == 0) { 262 if (ia->ia_ifp->if_flags & IFF_BROADCAST) 263 ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr; 264 else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) 265 ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr; 266 } 267 reflect: 268 ip->ip_len += hlen; /* since ip_input deducts this */ 269 icmpstat.icps_reflect++; 270 icmpstat.icps_outhist[icp->icmp_type]++; 271 icmp_reflect(ip, ifp); 272 return; 273 274 case ICMP_REDIRECT: 275 if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)) { 276 icmpstat.icps_badlen++; 277 break; 278 } 279 /* 280 * Short circuit routing redirects to force 281 * immediate change in the kernel's routing 282 * tables. The message is also handed to anyone 283 * listening on a raw socket (e.g. the routing 284 * daemon for use in updating its tables). 285 */ 286 icmpgw.sin_addr = ip->ip_src; 287 icmpdst.sin_addr = icp->icmp_gwaddr; 288 #ifdef ICMPPRINTFS 289 if (icmpprintfs) 290 printf("redirect dst %x to %x\n", icp->icmp_ip.ip_dst, 291 icp->icmp_gwaddr); 292 #endif 293 if (code == ICMP_REDIRECT_NET || code == ICMP_REDIRECT_TOSNET) { 294 icmpsrc.sin_addr = 295 in_makeaddr(in_netof(icp->icmp_ip.ip_dst), INADDR_ANY); 296 rtredirect((struct sockaddr *)&icmpsrc, 297 (struct sockaddr *)&icmpdst, RTF_GATEWAY, 298 (struct sockaddr *)&icmpgw); 299 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 300 pfctlinput(PRC_REDIRECT_NET, 301 (struct sockaddr *)&icmpsrc); 302 } else { 303 icmpsrc.sin_addr = icp->icmp_ip.ip_dst; 304 rtredirect((struct sockaddr *)&icmpsrc, 305 (struct sockaddr *)&icmpdst, RTF_GATEWAY | RTF_HOST, 306 (struct sockaddr *)&icmpgw); 307 pfctlinput(PRC_REDIRECT_HOST, 308 (struct sockaddr *)&icmpsrc); 309 } 310 break; 311 312 /* 313 * No kernel processing for the following; 314 * just fall through to send to raw listener. 315 */ 316 case ICMP_ECHOREPLY: 317 case ICMP_TSTAMPREPLY: 318 case ICMP_IREQREPLY: 319 case ICMP_MASKREPLY: 320 default: 321 break; 322 } 323 324 raw: 325 icmpsrc.sin_addr = ip->ip_src; 326 icmpdst.sin_addr = ip->ip_dst; 327 raw_input(m, &icmproto, (struct sockaddr *)&icmpsrc, 328 (struct sockaddr *)&icmpdst); 329 return; 330 331 free: 332 m_freem(m); 333 } 334 335 /* 336 * Reflect the ip packet back to the source 337 */ 338 icmp_reflect(ip, ifp) 339 register struct ip *ip; 340 struct ifnet *ifp; 341 { 342 register struct in_ifaddr *ia; 343 struct in_addr t; 344 struct mbuf *opts = 0, *ip_srcroute(); 345 int optlen = (ip->ip_hl << 2) - sizeof(struct ip); 346 347 t = ip->ip_dst; 348 ip->ip_dst = ip->ip_src; 349 /* 350 * If the incoming packet was addressed directly to us, 351 * use dst as the src for the reply. Otherwise (broadcast 352 * or anonymous), use the address which corresponds 353 * to the incoming interface. 354 */ 355 for (ia = in_ifaddr; ia; ia = ia->ia_next) { 356 if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) 357 break; 358 if ((ia->ia_ifp->if_flags & IFF_BROADCAST) && 359 t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr) 360 break; 361 } 362 if (ia == (struct in_ifaddr *)0) 363 ia = ifptoia(ifp); 364 if (ia == (struct in_ifaddr *)0) 365 ia = in_ifaddr; 366 t = IA_SIN(ia)->sin_addr; 367 ip->ip_src = t; 368 ip->ip_ttl = MAXTTL; 369 370 if (optlen > 0) { 371 /* 372 * Retrieve any source routing from the incoming packet 373 * and strip out other options. Adjust the IP length. 374 */ 375 opts = ip_srcroute(); 376 ip->ip_len -= optlen; 377 ip_stripoptions(ip, (struct mbuf *)0); 378 } 379 icmp_send(ip, opts); 380 if (opts) 381 (void)m_free(opts); 382 } 383 384 struct in_ifaddr * 385 ifptoia(ifp) 386 struct ifnet *ifp; 387 { 388 register struct in_ifaddr *ia; 389 390 for (ia = in_ifaddr; ia; ia = ia->ia_next) 391 if (ia->ia_ifp == ifp) 392 return (ia); 393 return ((struct in_ifaddr *)0); 394 } 395 396 /* 397 * Send an icmp packet back to the ip level, 398 * after supplying a checksum. 399 */ 400 icmp_send(ip, opts) 401 register struct ip *ip; 402 struct mbuf *opts; 403 { 404 register int hlen; 405 register struct icmp *icp; 406 register struct mbuf *m; 407 408 m = dtom(ip); 409 hlen = ip->ip_hl << 2; 410 m->m_off += hlen; 411 m->m_len -= hlen; 412 icp = mtod(m, struct icmp *); 413 icp->icmp_cksum = 0; 414 icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen); 415 m->m_off -= hlen; 416 m->m_len += hlen; 417 #ifdef ICMPPRINTFS 418 if (icmpprintfs) 419 printf("icmp_send dst %x src %x\n", ip->ip_dst, ip->ip_src); 420 #endif 421 (void) ip_output(m, opts, (struct route *)0, 0); 422 } 423 424 n_time 425 iptime() 426 { 427 struct timeval atv; 428 u_long t; 429 430 microtime(&atv); 431 t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; 432 return (htonl(t)); 433 } 434