in6_src.c revision 1.99
1/* $OpenBSD: in6_src.c,v 1.99 2024/04/21 17:32:11 florian 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 rtentry *rt; 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, &inp->inp_route, &ifp, 122 rtableid); 123 if (error) 124 return (error); 125 126 bzero(&sa6, sizeof(sa6)); 127 sa6.sin6_family = AF_INET6; 128 sa6.sin6_len = sizeof(sa6); 129 sa6.sin6_addr = pi->ipi6_addr; 130 131 if (ifp && IN6_IS_SCOPE_EMBED(&sa6.sin6_addr)) 132 sa6.sin6_addr.s6_addr16[1] = htons(ifp->if_index); 133 if_put(ifp); /* put reference from in6_selectif */ 134 135 ia6 = ifatoia6(ifa_ifwithaddr(sin6tosa(&sa6), rtableid)); 136 if (ia6 == NULL || (ia6->ia6_flags & 137 (IN6_IFF_ANYCAST|IN6_IFF_TENTATIVE|IN6_IFF_DUPLICATED))) 138 return (EADDRNOTAVAIL); 139 140 pi->ipi6_addr = sa6.sin6_addr; /* XXX: this overrides pi */ 141 142 *in6src = &pi->ipi6_addr; 143 return (0); 144 } 145 146 /* 147 * If the source address is not specified but the socket(if any) 148 * is already bound, use the bound address. 149 */ 150 if (laddr && !IN6_IS_ADDR_UNSPECIFIED(laddr)) { 151 *in6src = laddr; 152 return (0); 153 } 154 155 /* 156 * If the caller doesn't specify the source address but 157 * the outgoing interface, use an address associated with 158 * the interface. 159 */ 160 if (pi && pi->ipi6_ifindex) { 161 ifp = if_get(pi->ipi6_ifindex); 162 if (ifp == NULL) 163 return (ENXIO); /* XXX: better error? */ 164 165 ia6 = in6_ifawithscope(ifp, dst, rtableid, NULL); 166 if_put(ifp); 167 168 if (ia6 == NULL) 169 return (EADDRNOTAVAIL); 170 171 *in6src = &ia6->ia_addr.sin6_addr; 172 return (0); 173 } 174 175 error = in6_selectsrc(in6src, dstsock, mopts, rtableid); 176 if (error != EADDRNOTAVAIL) 177 return (error); 178 179 /* 180 * If route is known or can be allocated now, 181 * our src addr is taken from the i/f, else punt. 182 */ 183 rt = route6_mpath(&inp->inp_route, dst, NULL, rtableid); 184 185 /* 186 * in_pcbconnect() checks out IFF_LOOPBACK to skip using 187 * the address. But we don't know why it does so. 188 * It is necessary to ensure the scope even for lo0 189 * so doesn't check out IFF_LOOPBACK. 190 */ 191 192 if (rt != NULL) { 193 ifp = if_get(rt->rt_ifidx); 194 if (ifp != NULL) { 195 ia6 = in6_ifawithscope(ifp, dst, rtableid, rt); 196 if_put(ifp); 197 } 198 if (ia6 == NULL) /* xxx scope error ?*/ 199 ia6 = ifatoia6(rt->rt_ifa); 200 } 201 202 /* 203 * Use preferred source address if : 204 * - destination is not onlink 205 * - preferred source address is set 206 * - output interface is UP 207 */ 208 if (rt != NULL && !(rt->rt_flags & RTF_LLINFO) && 209 !(rt->rt_flags & RTF_HOST)) { 210 ip6_source = rtable_getsource(rtableid, AF_INET6); 211 if (ip6_source != NULL) { 212 struct ifaddr *ifa; 213 if ((ifa = ifa_ifwithaddr(ip6_source, rtableid)) != 214 NULL && ISSET(ifa->ifa_ifp->if_flags, IFF_UP)) { 215 *in6src = &satosin6(ip6_source)->sin6_addr; 216 return (0); 217 } 218 } 219 } 220 221 if (ia6 == NULL) 222 return (EHOSTUNREACH); /* no route */ 223 224 *in6src = &ia6->ia_addr.sin6_addr; 225 return (0); 226} 227 228/* 229 * Return an IPv6 address, which is the most appropriate for a given 230 * destination and multicast options. 231 * If necessary, this function lookups the routing table and returns 232 * an entry to the caller for later use. 233 */ 234int 235in6_selectsrc(const struct in6_addr **in6src, struct sockaddr_in6 *dstsock, 236 struct ip6_moptions *mopts, unsigned int rtableid) 237{ 238 struct ifnet *ifp = NULL; 239 struct in6_addr *dst; 240 struct in6_ifaddr *ia6 = NULL; 241 242 dst = &dstsock->sin6_addr; 243 244 /* 245 * If the destination address is a link-local unicast address or 246 * a link/interface-local multicast address, and if the outgoing 247 * interface is specified by the sin6_scope_id filed, use an address 248 * associated with the interface. 249 * XXX: We're now trying to define more specific semantics of 250 * sin6_scope_id field, so this part will be rewritten in 251 * the near future. 252 */ 253 if ((IN6_IS_ADDR_LINKLOCAL(dst) || IN6_IS_ADDR_MC_LINKLOCAL(dst) || 254 IN6_IS_ADDR_MC_INTFACELOCAL(dst)) && dstsock->sin6_scope_id) { 255 ifp = if_get(dstsock->sin6_scope_id); 256 if (ifp == NULL) 257 return (ENXIO); /* XXX: better error? */ 258 259 ia6 = in6_ifawithscope(ifp, dst, rtableid, NULL); 260 if_put(ifp); 261 262 if (ia6 == NULL) 263 return (EADDRNOTAVAIL); 264 265 *in6src = &ia6->ia_addr.sin6_addr; 266 return (0); 267 } 268 269 /* 270 * If the destination address is a multicast address and 271 * the outgoing interface for the address is specified 272 * by the caller, use an address associated with the interface. 273 * Even if the outgoing interface is not specified, we also 274 * choose a loopback interface as the outgoing interface. 275 */ 276 if (IN6_IS_ADDR_MULTICAST(dst)) { 277 ifp = mopts ? if_get(mopts->im6o_ifidx) : NULL; 278 279 if (!ifp && dstsock->sin6_scope_id) 280 ifp = if_get(htons(dstsock->sin6_scope_id)); 281 282 if (ifp) { 283 ia6 = in6_ifawithscope(ifp, dst, rtableid, NULL); 284 if_put(ifp); 285 286 if (ia6 == NULL) 287 return (EADDRNOTAVAIL); 288 289 *in6src = &ia6->ia_addr.sin6_addr; 290 return (0); 291 } 292 } 293 294 return (EADDRNOTAVAIL); 295} 296 297struct rtentry * 298in6_selectroute(const struct in6_addr *dst, struct ip6_pktopts *opts, 299 struct route *ro, unsigned int rtableid) 300{ 301 /* 302 * Use a cached route if it exists and is valid, else try to allocate 303 * a new one. 304 */ 305 if (ro) { 306 struct rtentry *rt; 307 308 rt = route6_mpath(ro, dst, NULL, rtableid); 309 310 /* 311 * Check if the outgoing interface conflicts with 312 * the interface specified by ipi6_ifindex (if specified). 313 * Note that loopback interface is always okay. 314 * (this may happen when we are sending a packet to one of 315 * our own addresses.) 316 */ 317 if (opts && opts->ip6po_pktinfo && 318 opts->ip6po_pktinfo->ipi6_ifindex) { 319 if (rt != NULL && !ISSET(rt->rt_flags, RTF_LOCAL) && 320 rt->rt_ifidx != opts->ip6po_pktinfo->ipi6_ifindex) { 321 return (NULL); 322 } 323 } 324 325 return (rt); 326 } 327 328 return (NULL); 329} 330 331int 332in6_selectif(const struct in6_addr *dst, struct ip6_pktopts *opts, 333 struct ip6_moptions *mopts, struct route *ro, struct ifnet **retifp, 334 u_int rtableid) 335{ 336 struct rtentry *rt; 337 struct in6_pktinfo *pi = NULL; 338 339 /* If the caller specify the outgoing interface explicitly, use it. */ 340 if (opts && (pi = opts->ip6po_pktinfo) != NULL && pi->ipi6_ifindex) { 341 *retifp = if_get(pi->ipi6_ifindex); 342 if (*retifp != NULL) 343 return (0); 344 } 345 346 /* 347 * If the destination address is a multicast address and the outgoing 348 * interface for the address is specified by the caller, use it. 349 */ 350 if (IN6_IS_ADDR_MULTICAST(dst) && 351 mopts != NULL && (*retifp = if_get(mopts->im6o_ifidx)) != NULL) 352 return (0); 353 354 rt = in6_selectroute(dst, opts, ro, rtableid); 355 if (rt == NULL) 356 return (EHOSTUNREACH); 357 358 /* 359 * do not use a rejected or black hole route. 360 * XXX: this check should be done in the L2 output routine. 361 * However, if we skipped this check here, we'd see the following 362 * scenario: 363 * - install a rejected route for a scoped address prefix 364 * (like fe80::/10) 365 * - send a packet to a destination that matches the scoped prefix, 366 * with ambiguity about the scope zone. 367 * - pick the outgoing interface from the route, and disambiguate the 368 * scope zone with the interface. 369 * - ip6_output() would try to get another route with the "new" 370 * destination, which may be valid. 371 * - we'd see no error on output. 372 * Although this may not be very harmful, it should still be confusing. 373 * We thus reject the case here. 374 */ 375 if (ISSET(rt->rt_flags, RTF_REJECT | RTF_BLACKHOLE)) 376 return (rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH); 377 378 *retifp = if_get(rt->rt_ifidx); 379 380 return (0); 381} 382 383int 384in6_selecthlim(const struct inpcb *inp) 385{ 386 if (inp && inp->inp_hops >= 0) 387 return (inp->inp_hops); 388 389 return (ip6_defhlim); 390} 391 392/* 393 * generate kernel-internal form (scopeid embedded into s6_addr16[1]). 394 * If the address scope of is link-local, embed the interface index in the 395 * address. The routine determines our precedence 396 * between advanced API scope/interface specification and basic API 397 * specification. 398 * 399 * this function should be nuked in the future, when we get rid of 400 * embedded scopeid thing. 401 * 402 * XXX actually, it is over-specification to return ifp against sin6_scope_id. 403 * there can be multiple interfaces that belong to a particular scope zone 404 * (in specification, we have 1:N mapping between a scope zone and interfaces). 405 * we may want to change the function to return something other than ifp. 406 */ 407int 408in6_embedscope(struct in6_addr *in6, const struct sockaddr_in6 *sin6, 409 const struct ip6_pktopts *outputopts6, const struct ip6_moptions *moptions6) 410{ 411 u_int32_t scopeid; 412 413 *in6 = sin6->sin6_addr; 414 415 /* 416 * don't try to read sin6->sin6_addr beyond here, since the caller may 417 * ask us to overwrite existing sockaddr_in6 418 */ 419 420 if (IN6_IS_SCOPE_EMBED(in6)) { 421 struct in6_pktinfo *pi; 422 423 /* 424 * KAME assumption: link id == interface id 425 */ 426 427 if (outputopts6 && (pi = outputopts6->ip6po_pktinfo) && 428 pi->ipi6_ifindex) 429 scopeid = pi->ipi6_ifindex; 430 else if (moptions6 && IN6_IS_ADDR_MULTICAST(in6) && 431 moptions6->im6o_ifidx) 432 scopeid = moptions6->im6o_ifidx; 433 else 434 scopeid = sin6->sin6_scope_id; 435 436 if (scopeid) { 437 struct ifnet *ifp; 438 439 ifp = if_get(scopeid); 440 if (ifp == NULL) 441 return ENXIO; /* XXX EINVAL? */ 442 /*XXX assignment to 16bit from 32bit variable */ 443 in6->s6_addr16[1] = htons(scopeid & 0xffff); 444 if_put(ifp); 445 } 446 } 447 448 return 0; 449} 450 451/* 452 * generate standard sockaddr_in6 from embedded form. 453 * touches sin6_addr and sin6_scope_id only. 454 * 455 * this function should be nuked in the future, when we get rid of 456 * embedded scopeid thing. 457 */ 458void 459in6_recoverscope(struct sockaddr_in6 *sin6, const struct in6_addr *in6) 460{ 461 u_int32_t scopeid; 462 463 sin6->sin6_addr = *in6; 464 465 /* 466 * don't try to read *in6 beyond here, since the caller may 467 * ask us to overwrite existing sockaddr_in6 468 */ 469 470 sin6->sin6_scope_id = 0; 471 if (IN6_IS_SCOPE_EMBED(in6)) { 472 /* 473 * KAME assumption: link id == interface id 474 */ 475 scopeid = ntohs(sin6->sin6_addr.s6_addr16[1]); 476 if (scopeid) { 477 sin6->sin6_addr.s6_addr16[1] = 0; 478 sin6->sin6_scope_id = scopeid; 479 } 480 } 481} 482 483/* 484 * just clear the embedded scope identifier. 485 */ 486void 487in6_clearscope(struct in6_addr *addr) 488{ 489 if (IN6_IS_SCOPE_EMBED(addr)) 490 addr->s6_addr16[1] = 0; 491} 492