/*      $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);
}