/* $OpenBSD: in6_src.c,v 1.104 2025/07/18 08:39:14 mvs Exp $ */ /* $KAME: in6_src.c,v 1.36 2001/02/06 04:08:17 itojun Exp $ */ /* * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the project nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * Copyright (c) 1982, 1986, 1991, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)in_pcb.c 8.2 (Berkeley) 1/4/94 */ #include <sys/param.h> #include <sys/systm.h> #include <sys/socket.h> #include <sys/errno.h> #include <net/if.h> #include <net/if_var.h> #include <net/route.h> #include <netinet/in.h> #include <netinet/ip.h> #include <netinet/in_pcb.h> #include <netinet6/in6_var.h> #include <netinet6/ip6_var.h> int in6_selectif(const struct in6_addr *, struct ip6_pktopts *, struct ip6_moptions *, struct route *, struct ifnet **, u_int); /* * Return an IPv6 address, which is the most appropriate for a given * destination and pcb. We need the additional opt parameter because * the values set at pcb level can be overridden via cmsg. */ int in6_pcbselsrc(const struct in6_addr **in6src, const struct sockaddr_in6 *dstsock, struct inpcb *inp, struct ip6_pktopts *opts) { const struct in6_addr *dst = &dstsock->sin6_addr; const struct in6_addr *laddr = &inp->inp_laddr6; struct rtentry *rt; struct ip6_moptions *mopts = inp->inp_moptions6; u_int rtableid = inp->inp_rtableid; struct ifnet *ifp = NULL; struct sockaddr *ip6_source = NULL; struct in6_ifaddr *ia6 = NULL; struct in6_pktinfo *pi = NULL; int error; /* * If the source address is explicitly specified by the caller, * check if the requested source address is indeed a unicast address * assigned to the node, and can be used as the packet's source * address. If everything is okay, use the address as source. */ if (opts && (pi = opts->ip6po_pktinfo) && !IN6_IS_ADDR_UNSPECIFIED(&pi->ipi6_addr)) { struct sockaddr_in6 sa6; /* get the outgoing interface */ error = in6_selectif(dst, opts, mopts, &inp->inp_route, &ifp, rtableid); if (error) return (error); bzero(&sa6, sizeof(sa6)); sa6.sin6_family = AF_INET6; sa6.sin6_len = sizeof(sa6); sa6.sin6_addr = pi->ipi6_addr; if (ifp && IN6_IS_SCOPE_EMBED(&sa6.sin6_addr)) sa6.sin6_addr.s6_addr16[1] = htons(ifp->if_index); if_put(ifp); /* put reference from in6_selectif */ ia6 = ifatoia6(ifa_ifwithaddr(sin6tosa(&sa6), rtableid)); if (ia6 == NULL || (ia6->ia6_flags & (IN6_IFF_ANYCAST|IN6_IFF_TENTATIVE|IN6_IFF_DUPLICATED))) return (EADDRNOTAVAIL); pi->ipi6_addr = sa6.sin6_addr; /* XXX: this overrides pi */ *in6src = &pi->ipi6_addr; return (0); } /* * If the source address is not specified but the socket(if any) * is already bound, use the bound address. */ if (laddr && !IN6_IS_ADDR_UNSPECIFIED(laddr)) { *in6src = laddr; return (0); } /* * If the caller doesn't specify the source address but * the outgoing interface, use an address associated with * the interface. */ if (pi && pi->ipi6_ifindex) { ifp = if_get(pi->ipi6_ifindex); if (ifp == NULL) return (ENXIO); /* XXX: better error? */ ia6 = in6_ifawithscope(ifp, dst, rtableid, NULL); if_put(ifp); if (ia6 == NULL) return (EADDRNOTAVAIL); *in6src = &ia6->ia_addr.sin6_addr; return (0); } error = in6_selectsrc(in6src, dstsock, mopts, rtableid); if (error != EADDRNOTAVAIL) return (error); /* * If route is known or can be allocated now, * our src addr is taken from the i/f, else punt. */ rt = route6_mpath(&inp->inp_route, dst, NULL, rtableid); /* * in_pcbconnect() checks out IFF_LOOPBACK to skip using * the address. But we don't know why it does so. * It is necessary to ensure the scope even for lo0 * so doesn't check out IFF_LOOPBACK. */ if (rt != NULL) { ifp = if_get(rt->rt_ifidx); if (ifp != NULL) { ia6 = in6_ifawithscope(ifp, dst, rtableid, rt); if_put(ifp); } if (ia6 == NULL) /* xxx scope error ?*/ ia6 = ifatoia6(rt->rt_ifa); } /* * Use preferred source address if : * - destination is not onlink * - preferred source address is set * - output interface is UP */ if (rt != NULL && ISSET(rt->rt_flags, RTF_GATEWAY)) { ip6_source = rtable_getsource(rtableid, AF_INET6); if (ip6_source != NULL) { struct ifaddr *ifa; if ((ifa = ifa_ifwithaddr(ip6_source, rtableid)) != NULL && ISSET(ifa->ifa_ifp->if_flags, IFF_UP)) { *in6src = &satosin6(ip6_source)->sin6_addr; return (0); } } } if (ia6 == NULL) return (EHOSTUNREACH); /* no route */ *in6src = &ia6->ia_addr.sin6_addr; return (0); } /* * Return an IPv6 address, which is the most appropriate for a given * destination and multicast options. * If necessary, this function lookups the routing table and returns * an entry to the caller for later use. */ int in6_selectsrc(const struct in6_addr **in6src, const struct sockaddr_in6 *dstsock, struct ip6_moptions *mopts, unsigned int rtableid) { const struct in6_addr *dst = &dstsock->sin6_addr; struct ifnet *ifp = NULL; struct in6_ifaddr *ia6 = NULL; /* * If the destination address is a link-local unicast address or * a link/interface-local multicast address, and if the outgoing * interface is specified by the sin6_scope_id filed, use an address * associated with the interface. * XXX: We're now trying to define more specific semantics of * sin6_scope_id field, so this part will be rewritten in * the near future. */ if ((IN6_IS_ADDR_LINKLOCAL(dst) || IN6_IS_ADDR_MC_LINKLOCAL(dst) || IN6_IS_ADDR_MC_INTFACELOCAL(dst)) && dstsock->sin6_scope_id) { ifp = if_get(dstsock->sin6_scope_id); if (ifp == NULL) return (ENXIO); /* XXX: better error? */ ia6 = in6_ifawithscope(ifp, dst, rtableid, NULL); if_put(ifp); if (ia6 == NULL) return (EADDRNOTAVAIL); *in6src = &ia6->ia_addr.sin6_addr; return (0); } /* * If the destination address is a multicast address and * the outgoing interface for the address is specified * by the caller, use an address associated with the interface. * Even if the outgoing interface is not specified, we also * choose a loopback interface as the outgoing interface. */ if (IN6_IS_ADDR_MULTICAST(dst)) { ifp = mopts ? if_get(mopts->im6o_ifidx) : NULL; if (!ifp && dstsock->sin6_scope_id) ifp = if_get(htons(dstsock->sin6_scope_id)); if (ifp) { ia6 = in6_ifawithscope(ifp, dst, rtableid, NULL); if_put(ifp); if (ia6 == NULL) return (EADDRNOTAVAIL); *in6src = &ia6->ia_addr.sin6_addr; return (0); } } return (EADDRNOTAVAIL); } struct rtentry * in6_selectroute(const struct in6_addr *dst, struct ip6_pktopts *opts, struct route *ro, unsigned int rtableid) { /* * Use a cached route if it exists and is valid, else try to allocate * a new one. */ if (ro) { struct rtentry *rt; rt = route6_mpath(ro, dst, NULL, rtableid); /* * Check if the outgoing interface conflicts with * the interface specified by ipi6_ifindex (if specified). * Note that loopback interface is always okay. * (this may happen when we are sending a packet to one of * our own addresses.) */ if (opts && opts->ip6po_pktinfo && opts->ip6po_pktinfo->ipi6_ifindex) { if (rt != NULL && !ISSET(rt->rt_flags, RTF_LOCAL) && rt->rt_ifidx != opts->ip6po_pktinfo->ipi6_ifindex) { return (NULL); } } return (rt); } return (NULL); } int in6_selectif(const struct in6_addr *dst, struct ip6_pktopts *opts, struct ip6_moptions *mopts, struct route *ro, struct ifnet **retifp, u_int rtableid) { struct rtentry *rt; struct in6_pktinfo *pi = NULL; /* If the caller specify the outgoing interface explicitly, use it. */ if (opts && (pi = opts->ip6po_pktinfo) != NULL && pi->ipi6_ifindex) { *retifp = if_get(pi->ipi6_ifindex); if (*retifp != NULL) return (0); } /* * If the destination address is a multicast address and the outgoing * interface for the address is specified by the caller, use it. */ if (IN6_IS_ADDR_MULTICAST(dst) && mopts != NULL && (*retifp = if_get(mopts->im6o_ifidx)) != NULL) return (0); rt = in6_selectroute(dst, opts, ro, rtableid); if (rt == NULL) return (EHOSTUNREACH); /* * do not use a rejected or black hole route. * XXX: this check should be done in the L2 output routine. * However, if we skipped this check here, we'd see the following * scenario: * - install a rejected route for a scoped address prefix * (like fe80::/10) * - send a packet to a destination that matches the scoped prefix, * with ambiguity about the scope zone. * - pick the outgoing interface from the route, and disambiguate the * scope zone with the interface. * - ip6_output() would try to get another route with the "new" * destination, which may be valid. * - we'd see no error on output. * Although this may not be very harmful, it should still be confusing. * We thus reject the case here. */ if (ISSET(rt->rt_flags, RTF_REJECT | RTF_BLACKHOLE)) return (rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH); *retifp = if_get(rt->rt_ifidx); return (0); } int in6_selecthlim(const struct inpcb *inp) { if (inp && inp->inp_hops >= 0) return (inp->inp_hops); return (atomic_load_int(&ip6_defhlim)); } /* * generate kernel-internal form (scopeid embedded into s6_addr16[1]). * If the address scope of is link-local, embed the interface index in the * address. The routine determines our precedence * between advanced API scope/interface specification and basic API * specification. * * this function should be nuked in the future, when we get rid of * embedded scopeid thing. * * XXX actually, it is over-specification to return ifp against sin6_scope_id. * there can be multiple interfaces that belong to a particular scope zone * (in specification, we have 1:N mapping between a scope zone and interfaces). * we may want to change the function to return something other than ifp. */ int in6_embedscope(struct in6_addr *in6, const struct sockaddr_in6 *sin6, const struct ip6_pktopts *outputopts6, const struct ip6_moptions *moptions6) { u_int32_t scopeid; *in6 = sin6->sin6_addr; /* * don't try to read sin6->sin6_addr beyond here, since the caller may * ask us to overwrite existing sockaddr_in6 */ if (IN6_IS_SCOPE_EMBED(in6)) { struct in6_pktinfo *pi; /* * KAME assumption: link id == interface id */ if (outputopts6 && (pi = outputopts6->ip6po_pktinfo) && pi->ipi6_ifindex) scopeid = pi->ipi6_ifindex; else if (moptions6 && IN6_IS_ADDR_MULTICAST(in6) && moptions6->im6o_ifidx) scopeid = moptions6->im6o_ifidx; else scopeid = sin6->sin6_scope_id; if (scopeid) { struct ifnet *ifp; ifp = if_get(scopeid); if (ifp == NULL) return ENXIO; /* XXX EINVAL? */ /*XXX assignment to 16bit from 32bit variable */ in6->s6_addr16[1] = htons(scopeid & 0xffff); if_put(ifp); } } return 0; } /* * generate standard sockaddr_in6 from embedded form. * touches sin6_addr and sin6_scope_id only. * * this function should be nuked in the future, when we get rid of * embedded scopeid thing. */ void in6_recoverscope(struct sockaddr_in6 *sin6, const struct in6_addr *in6) { u_int32_t scopeid; sin6->sin6_addr = *in6; /* * don't try to read *in6 beyond here, since the caller may * ask us to overwrite existing sockaddr_in6 */ sin6->sin6_scope_id = 0; if (IN6_IS_SCOPE_EMBED(in6)) { /* * KAME assumption: link id == interface id */ scopeid = ntohs(sin6->sin6_addr.s6_addr16[1]); if (scopeid) { sin6->sin6_addr.s6_addr16[1] = 0; sin6->sin6_scope_id = scopeid; } } } /* * just clear the embedded scope identifier. */ void in6_clearscope(struct in6_addr *addr) { if (IN6_IS_SCOPE_EMBED(addr)) addr->s6_addr16[1] = 0; }
