/*      $NetBSD: nd6_rtr.c,v 1.149 2020/06/12 11:04:45 roy Exp $        */
/*      $KAME: nd6_rtr.c,v 1.95 2001/02/07 08:09:47 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: nd6_rtr.c,v 1.149 2020/06/12 11:04:45 roy Exp $");

#ifdef _KERNEL_OPT
#include "opt_net_mpsafe.h"
#endif

#include <sys/mbuf.h>
#include <sys/syslog.h>

#include <net/if.h>

#include <netinet/in.h>
#include <netinet6/in6_var.h>
#include <netinet/ip6.h>
#include <netinet6/nd6.h>
#include <netinet/icmp6.h>
#include <netinet6/icmp6_private.h>

/*
 * Cache the source link layer address of Router Advertisement
 * and Solicition messages.
 */
void
nd6_rtr_cache(struct mbuf *m, int off, int icmp6len, int icmp6_type)
{
        struct ifnet *ifp;
        struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
        struct nd_router_solicit *nd_rs;
        struct nd_router_advert *nd_ra;
        struct in6_addr saddr6 = ip6->ip6_src;
        char *lladdr = NULL;
        int lladdrlen = 0;
        union nd_opts ndopts;
        struct psref psref;
        char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];

        ifp = m_get_rcvif_psref(m, &psref);
        if (ifp == NULL)
                goto freeit;

        /* Sanity checks */
        if (ip6->ip6_hlim != 255) {
                nd6log(LOG_ERR, "invalid hlim (%d) from %s to %s on %s\n",
                    ip6->ip6_hlim, IN6_PRINT(ip6bufs, &ip6->ip6_src),
                    IN6_PRINT(ip6bufd, &ip6->ip6_dst), if_name(ifp));
                goto bad;
        }

        switch (icmp6_type) {
        case ND_ROUTER_SOLICIT:
                /*
                 * Don't update the neighbor cache, if src = ::.
                 * This indicates that the src has no IP address assigned yet.
                 */
                if (IN6_IS_ADDR_UNSPECIFIED(&saddr6))
                        goto freeit;

                IP6_EXTHDR_GET(nd_rs, struct nd_router_solicit *, m, off,
                    icmp6len);
                if (nd_rs == NULL) {
                        ICMP6_STATINC(ICMP6_STAT_TOOSHORT);
                        m_put_rcvif_psref(ifp, &psref);
                        return;
                }

                icmp6len -= sizeof(*nd_rs);
                nd6_option_init(nd_rs + 1, icmp6len, &ndopts);
                break;
        case ND_ROUTER_ADVERT:
                if (!IN6_IS_ADDR_LINKLOCAL(&saddr6)) {
                        nd6log(LOG_ERR, "src %s is not link-local\n",
                            IN6_PRINT(ip6bufs, &saddr6));
                        goto bad;
                }

                IP6_EXTHDR_GET(nd_ra, struct nd_router_advert *, m, off,
                    icmp6len);
                if (nd_ra == NULL) {
                        ICMP6_STATINC(ICMP6_STAT_TOOSHORT);
                        m_put_rcvif_psref(ifp, &psref);
                        return;
                }

                icmp6len -= sizeof(*nd_ra);
                nd6_option_init(nd_ra + 1, icmp6len, &ndopts);
                break;
        }

        if (nd6_options(&ndopts) < 0) {
                nd6log(LOG_INFO, "invalid ND option, ignored\n");
                /* nd6_options have incremented stats */
                goto freeit;
        }

        if (ndopts.nd_opts_src_lladdr) {
                lladdr = (char *)(ndopts.nd_opts_src_lladdr + 1);
                lladdrlen = ndopts.nd_opts_src_lladdr->nd_opt_len << 3;
        }

        if (lladdr && ((ifp->if_addrlen + 2 + 7) & ~7) != lladdrlen) {
                nd6log(LOG_INFO, "lladdrlen mismatch for %s "
                    "(if %d, %s packet %d)\n",
                    IN6_PRINT(ip6bufs, &saddr6),
                    ifp->if_addrlen,
                    icmp6_type == ND_ROUTER_SOLICIT ? "RS" : "RA",
                    lladdrlen - 2);
                goto bad;
        }

        nd6_cache_lladdr(ifp, &saddr6, lladdr, lladdrlen, icmp6_type, 0);

freeit:
        m_put_rcvif_psref(ifp, &psref);
        m_freem(m);
        return;

bad:
        ICMP6_STATINC(icmp6_type == ND_ROUTER_SOLICIT ?
            ICMP6_STAT_BADRS : ICMP6_STAT_BADRA);
        m_put_rcvif_psref(ifp, &psref);
        m_freem(m);
}