in6_src.c revision 1.94
1/* $OpenBSD: in6_src.c,v 1.94 2024/02/13 12:22:09 bluhm Exp $ */ 2/* $KAME: in6_src.c,v 1.36 2001/02/06 04:08:17 itojun Exp $ */ 3 4/* 5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the project nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33/* 34 * Copyright (c) 1982, 1986, 1991, 1993 35 * The Regents of the University of California. All rights reserved. 36 * 37 * Redistribution and use in source and binary forms, with or without 38 * modification, are permitted provided that the following conditions 39 * are met: 40 * 1. Redistributions of source code must retain the above copyright 41 * notice, this list of conditions and the following disclaimer. 42 * 2. Redistributions in binary form must reproduce the above copyright 43 * notice, this list of conditions and the following disclaimer in the 44 * documentation and/or other materials provided with the distribution. 45 * 3. Neither the name of the University nor the names of its contributors 46 * may be used to endorse or promote products derived from this software 47 * without specific prior written permission. 48 * 49 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 50 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 51 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 52 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 53 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 54 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 55 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 56 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 57 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 58 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 59 * SUCH DAMAGE. 60 * 61 * @(#)in_pcb.c 8.2 (Berkeley) 1/4/94 62 */ 63 64#include <sys/param.h> 65#include <sys/systm.h> 66#include <sys/mbuf.h> 67#include <sys/socket.h> 68#include <sys/socketvar.h> 69#include <sys/ioctl.h> 70#include <sys/errno.h> 71#include <sys/time.h> 72 73#include <net/if.h> 74#include <net/if_var.h> 75#include <net/route.h> 76 77#include <netinet/in.h> 78#include <netinet/ip.h> 79#include <netinet/in_pcb.h> 80#include <netinet6/in6_var.h> 81#include <netinet/ip6.h> 82#include <netinet6/ip6_var.h> 83#include <netinet6/nd6.h> 84 85int in6_selectif(const struct in6_addr *, struct ip6_pktopts *, 86 struct ip6_moptions *, struct route *, struct ifnet **, u_int); 87 88/* 89 * Return an IPv6 address, which is the most appropriate for a given 90 * destination and pcb. We need the additional opt parameter because 91 * the values set at pcb level can be overridden via cmsg. 92 */ 93int 94in6_pcbselsrc(const struct in6_addr **in6src, struct sockaddr_in6 *dstsock, 95 struct inpcb *inp, struct ip6_pktopts *opts) 96{ 97 struct ip6_moptions *mopts = inp->inp_moptions6; 98 struct route *ro = &inp->inp_route; 99 const struct in6_addr *laddr = &inp->inp_laddr6; 100 u_int rtableid = inp->inp_rtableid; 101 struct ifnet *ifp = NULL; 102 struct sockaddr *ip6_source = NULL; 103 struct in6_addr *dst; 104 struct in6_ifaddr *ia6 = NULL; 105 struct in6_pktinfo *pi = NULL; 106 int error; 107 108 dst = &dstsock->sin6_addr; 109 110 /* 111 * If the source address is explicitly specified by the caller, 112 * check if the requested source address is indeed a unicast address 113 * assigned to the node, and can be used as the packet's source 114 * address. If everything is okay, use the address as source. 115 */ 116 if (opts && (pi = opts->ip6po_pktinfo) && 117 !IN6_IS_ADDR_UNSPECIFIED(&pi->ipi6_addr)) { 118 struct sockaddr_in6 sa6; 119 120 /* get the outgoing interface */ 121 error = in6_selectif(dst, opts, mopts, ro, &ifp, rtableid); 122 if (error) 123 return (error); 124 125 bzero(&sa6, sizeof(sa6)); 126 sa6.sin6_family = AF_INET6; 127 sa6.sin6_len = sizeof(sa6); 128 sa6.sin6_addr = pi->ipi6_addr; 129 130 if (ifp && IN6_IS_SCOPE_EMBED(&sa6.sin6_addr)) 131 sa6.sin6_addr.s6_addr16[1] = htons(ifp->if_index); 132 if_put(ifp); /* put reference from in6_selectif */ 133 134 ia6 = ifatoia6(ifa_ifwithaddr(sin6tosa(&sa6), rtableid)); 135 if (ia6 == NULL || (ia6->ia6_flags & 136 (IN6_IFF_ANYCAST|IN6_IFF_TENTATIVE|IN6_IFF_DUPLICATED))) 137 return (EADDRNOTAVAIL); 138 139 pi->ipi6_addr = sa6.sin6_addr; /* XXX: this overrides pi */ 140 141 *in6src = &pi->ipi6_addr; 142 return (0); 143 } 144 145 /* 146 * If the source address is not specified but the socket(if any) 147 * is already bound, use the bound address. 148 */ 149 if (laddr && !IN6_IS_ADDR_UNSPECIFIED(laddr)) { 150 *in6src = laddr; 151 return (0); 152 } 153 154 /* 155 * If the caller doesn't specify the source address but 156 * the outgoing interface, use an address associated with 157 * the interface. 158 */ 159 if (pi && pi->ipi6_ifindex) { 160 ifp = if_get(pi->ipi6_ifindex); 161 if (ifp == NULL) 162 return (ENXIO); /* XXX: better error? */ 163 164 ia6 = in6_ifawithscope(ifp, dst, rtableid); 165 if_put(ifp); 166 167 if (ia6 == NULL) 168 return (EADDRNOTAVAIL); 169 170 *in6src = &ia6->ia_addr.sin6_addr; 171 return (0); 172 } 173 174 error = in6_selectsrc(in6src, dstsock, mopts, rtableid); 175 if (error != EADDRNOTAVAIL) 176 return (error); 177 178 /* 179 * If route is known or can be allocated now, 180 * our src addr is taken from the i/f, else punt. 181 */ 182 if (route6_cache(ro, dst, rtableid)) { 183 ro->ro_rt = rtalloc(&ro->ro_dstsa, RT_RESOLVE, ro->ro_tableid); 184 } 185 186 /* 187 * in_pcbconnect() checks out IFF_LOOPBACK to skip using 188 * the address. But we don't know why it does so. 189 * It is necessary to ensure the scope even for lo0 190 * so doesn't check out IFF_LOOPBACK. 191 */ 192 193 if (ro->ro_rt) { 194 ifp = if_get(ro->ro_rt->rt_ifidx); 195 if (ifp != NULL) { 196 ia6 = in6_ifawithscope(ifp, dst, rtableid); 197 if_put(ifp); 198 } 199 if (ia6 == NULL) /* xxx scope error ?*/ 200 ia6 = ifatoia6(ro->ro_rt->rt_ifa); 201 } 202 203 /* 204 * Use preferred source address if : 205 * - destination is not onlink 206 * - preferred source address is set 207 * - output interface is UP 208 */ 209 if (ro->ro_rt && !(ro->ro_rt->rt_flags & RTF_LLINFO) && 210 !(ro->ro_rt->rt_flags & RTF_HOST)) { 211 ip6_source = rtable_getsource(rtableid, AF_INET6); 212 if (ip6_source != NULL) { 213 struct ifaddr *ifa; 214 if ((ifa = ifa_ifwithaddr(ip6_source, rtableid)) != 215 NULL && ISSET(ifa->ifa_ifp->if_flags, IFF_UP)) { 216 *in6src = &satosin6(ip6_source)->sin6_addr; 217 return (0); 218 } 219 } 220 } 221 222 if (ia6 == NULL) 223 return (EHOSTUNREACH); /* no route */ 224 225 *in6src = &ia6->ia_addr.sin6_addr; 226 return (0); 227} 228 229/* 230 * Return an IPv6 address, which is the most appropriate for a given 231 * destination and multicast options. 232 * If necessary, this function lookups the routing table and returns 233 * an entry to the caller for later use. 234 */ 235int 236in6_selectsrc(const struct in6_addr **in6src, struct sockaddr_in6 *dstsock, 237 struct ip6_moptions *mopts, unsigned int rtableid) 238{ 239 struct ifnet *ifp = NULL; 240 struct in6_addr *dst; 241 struct in6_ifaddr *ia6 = NULL; 242 243 dst = &dstsock->sin6_addr; 244 245 /* 246 * If the destination address is a link-local unicast address or 247 * a link/interface-local multicast address, and if the outgoing 248 * interface is specified by the sin6_scope_id filed, use an address 249 * associated with the interface. 250 * XXX: We're now trying to define more specific semantics of 251 * sin6_scope_id field, so this part will be rewritten in 252 * the near future. 253 */ 254 if ((IN6_IS_ADDR_LINKLOCAL(dst) || IN6_IS_ADDR_MC_LINKLOCAL(dst) || 255 IN6_IS_ADDR_MC_INTFACELOCAL(dst)) && dstsock->sin6_scope_id) { 256 ifp = if_get(dstsock->sin6_scope_id); 257 if (ifp == NULL) 258 return (ENXIO); /* XXX: better error? */ 259 260 ia6 = in6_ifawithscope(ifp, dst, rtableid); 261 if_put(ifp); 262 263 if (ia6 == NULL) 264 return (EADDRNOTAVAIL); 265 266 *in6src = &ia6->ia_addr.sin6_addr; 267 return (0); 268 } 269 270 /* 271 * If the destination address is a multicast address and 272 * the outgoing interface for the address is specified 273 * by the caller, use an address associated with the interface. 274 * Even if the outgoing interface is not specified, we also 275 * choose a loopback interface as the outgoing interface. 276 */ 277 if (IN6_IS_ADDR_MULTICAST(dst)) { 278 ifp = mopts ? if_get(mopts->im6o_ifidx) : NULL; 279 280 if (!ifp && dstsock->sin6_scope_id) 281 ifp = if_get(htons(dstsock->sin6_scope_id)); 282 283 if (ifp) { 284 ia6 = in6_ifawithscope(ifp, dst, rtableid); 285 if_put(ifp); 286 287 if (ia6 == NULL) 288 return (EADDRNOTAVAIL); 289 290 *in6src = &ia6->ia_addr.sin6_addr; 291 return (0); 292 } 293 } 294 295 return (EADDRNOTAVAIL); 296} 297 298struct rtentry * 299in6_selectroute(const struct in6_addr *dst, struct ip6_pktopts *opts, 300 struct route *ro, unsigned int rtableid) 301{ 302 /* 303 * Use a cached route if it exists and is valid, else try to allocate 304 * a new one. 305 */ 306 if (ro) { 307 if (route6_cache(ro, dst, rtableid)) { 308 /* No route yet, so try to acquire one */ 309 ro->ro_rt = rtalloc_mpath(&ro->ro_dstsa, NULL, 310 ro->ro_tableid); 311 } 312 313 /* 314 * Check if the outgoing interface conflicts with 315 * the interface specified by ipi6_ifindex (if specified). 316 * Note that loopback interface is always okay. 317 * (this may happen when we are sending a packet to one of 318 * our own addresses.) 319 */ 320 if (opts && opts->ip6po_pktinfo && 321 opts->ip6po_pktinfo->ipi6_ifindex) { 322 if (ro->ro_rt != NULL && 323 !ISSET(ro->ro_rt->rt_flags, RTF_LOCAL) && 324 ro->ro_rt->rt_ifidx != 325 opts->ip6po_pktinfo->ipi6_ifindex) { 326 return (NULL); 327 } 328 } 329 330 return (ro->ro_rt); 331 } 332 333 return (NULL); 334} 335 336int 337in6_selectif(const struct in6_addr *dst, struct ip6_pktopts *opts, 338 struct ip6_moptions *mopts, struct route *ro, struct ifnet **retifp, 339 u_int rtableid) 340{ 341 struct rtentry *rt = NULL; 342 struct in6_pktinfo *pi = NULL; 343 344 /* If the caller specify the outgoing interface explicitly, use it. */ 345 if (opts && (pi = opts->ip6po_pktinfo) != NULL && pi->ipi6_ifindex) { 346 *retifp = if_get(pi->ipi6_ifindex); 347 if (*retifp != NULL) 348 return (0); 349 } 350 351 /* 352 * If the destination address is a multicast address and the outgoing 353 * interface for the address is specified by the caller, use it. 354 */ 355 if (IN6_IS_ADDR_MULTICAST(dst) && 356 mopts != NULL && (*retifp = if_get(mopts->im6o_ifidx)) != NULL) 357 return (0); 358 359 rt = in6_selectroute(dst, opts, ro, rtableid); 360 if (rt == NULL) 361 return (EHOSTUNREACH); 362 363 /* 364 * do not use a rejected or black hole route. 365 * XXX: this check should be done in the L2 output routine. 366 * However, if we skipped this check here, we'd see the following 367 * scenario: 368 * - install a rejected route for a scoped address prefix 369 * (like fe80::/10) 370 * - send a packet to a destination that matches the scoped prefix, 371 * with ambiguity about the scope zone. 372 * - pick the outgoing interface from the route, and disambiguate the 373 * scope zone with the interface. 374 * - ip6_output() would try to get another route with the "new" 375 * destination, which may be valid. 376 * - we'd see no error on output. 377 * Although this may not be very harmful, it should still be confusing. 378 * We thus reject the case here. 379 */ 380 if (rt && (rt->rt_flags & (RTF_REJECT | RTF_BLACKHOLE))) 381 return (rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH); 382 383 if (rt != NULL) 384 *retifp = if_get(rt->rt_ifidx); 385 386 return (0); 387} 388 389int 390in6_selecthlim(const struct inpcb *inp) 391{ 392 if (inp && inp->inp_hops >= 0) 393 return (inp->inp_hops); 394 395 return (ip6_defhlim); 396} 397 398/* 399 * generate kernel-internal form (scopeid embedded into s6_addr16[1]). 400 * If the address scope of is link-local, embed the interface index in the 401 * address. The routine determines our precedence 402 * between advanced API scope/interface specification and basic API 403 * specification. 404 * 405 * this function should be nuked in the future, when we get rid of 406 * embedded scopeid thing. 407 * 408 * XXX actually, it is over-specification to return ifp against sin6_scope_id. 409 * there can be multiple interfaces that belong to a particular scope zone 410 * (in specification, we have 1:N mapping between a scope zone and interfaces). 411 * we may want to change the function to return something other than ifp. 412 */ 413int 414in6_embedscope(struct in6_addr *in6, const struct sockaddr_in6 *sin6, 415 const struct ip6_pktopts *outputopts6, const struct ip6_moptions *moptions6) 416{ 417 u_int32_t scopeid; 418 419 *in6 = sin6->sin6_addr; 420 421 /* 422 * don't try to read sin6->sin6_addr beyond here, since the caller may 423 * ask us to overwrite existing sockaddr_in6 424 */ 425 426 if (IN6_IS_SCOPE_EMBED(in6)) { 427 struct in6_pktinfo *pi; 428 429 /* 430 * KAME assumption: link id == interface id 431 */ 432 433 if (outputopts6 && (pi = outputopts6->ip6po_pktinfo) && 434 pi->ipi6_ifindex) 435 scopeid = pi->ipi6_ifindex; 436 else if (moptions6 && IN6_IS_ADDR_MULTICAST(in6) && 437 moptions6->im6o_ifidx) 438 scopeid = moptions6->im6o_ifidx; 439 else 440 scopeid = sin6->sin6_scope_id; 441 442 if (scopeid) { 443 struct ifnet *ifp; 444 445 ifp = if_get(scopeid); 446 if (ifp == NULL) 447 return ENXIO; /* XXX EINVAL? */ 448 /*XXX assignment to 16bit from 32bit variable */ 449 in6->s6_addr16[1] = htons(scopeid & 0xffff); 450 if_put(ifp); 451 } 452 } 453 454 return 0; 455} 456 457/* 458 * generate standard sockaddr_in6 from embedded form. 459 * touches sin6_addr and sin6_scope_id only. 460 * 461 * this function should be nuked in the future, when we get rid of 462 * embedded scopeid thing. 463 */ 464void 465in6_recoverscope(struct sockaddr_in6 *sin6, const struct in6_addr *in6) 466{ 467 u_int32_t scopeid; 468 469 sin6->sin6_addr = *in6; 470 471 /* 472 * don't try to read *in6 beyond here, since the caller may 473 * ask us to overwrite existing sockaddr_in6 474 */ 475 476 sin6->sin6_scope_id = 0; 477 if (IN6_IS_SCOPE_EMBED(in6)) { 478 /* 479 * KAME assumption: link id == interface id 480 */ 481 scopeid = ntohs(sin6->sin6_addr.s6_addr16[1]); 482 if (scopeid) { 483 sin6->sin6_addr.s6_addr16[1] = 0; 484 sin6->sin6_scope_id = scopeid; 485 } 486 } 487} 488 489/* 490 * just clear the embedded scope identifier. 491 */ 492void 493in6_clearscope(struct in6_addr *addr) 494{ 495 if (IN6_IS_SCOPE_EMBED(addr)) 496 addr->s6_addr16[1] = 0; 497} 498