/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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.
 *
 *      $KAME: dest6.c,v 1.59 2003/07/11 13:21:16 t-momose Exp $
 */

#include "opt_inet.h"
#include "opt_inet6.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/route.h>

#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet/icmp6.h>

/*
 * Destination options header processing.
 */
int
dest6_input(struct mbuf **mp, int *offp, int proto)
{
        struct mbuf *m;
        int off, dstoptlen, optlen;
        struct ip6_dest *dstopts;
        u_int8_t *opt;

        m = *mp;
        off = *offp;

        /* Validation of the length of the header. */
        if (m->m_len < off + sizeof(*dstopts)) {
                m = m_pullup(m, off + sizeof(*dstopts));
                if (m == NULL) {
                        IP6STAT_INC(ip6s_exthdrtoolong);
                        *mp = m;
                        return (IPPROTO_DONE);
                }
        }
        dstopts = (struct ip6_dest *)(mtod(m, caddr_t) + off);
        dstoptlen = (dstopts->ip6d_len + 1) << 3;

        if (m->m_len < off + dstoptlen) {
                m = m_pullup(m, off + dstoptlen);
                if (m == NULL) {
                        IP6STAT_INC(ip6s_exthdrtoolong);
                        *mp = m;
                        return (IPPROTO_DONE);
                }
        }
        dstopts = (struct ip6_dest *)(mtod(m, caddr_t) + off);
        off += dstoptlen;
        dstoptlen -= sizeof(struct ip6_dest);
        opt = (u_int8_t *)dstopts + sizeof(struct ip6_dest);

        /* search header for all options. */
        for (; dstoptlen > 0; dstoptlen -= optlen, opt += optlen) {
                if (*opt != IP6OPT_PAD1 &&
                    (dstoptlen < IP6OPT_MINLEN || *(opt + 1) + 2 > dstoptlen)) {
                        IP6STAT_INC(ip6s_toosmall);
                        goto bad;
                }

                switch (*opt) {
                case IP6OPT_PAD1:
                        optlen = 1;
                        break;
                case IP6OPT_PADN:
                        optlen = *(opt + 1) + 2;
                        break;
                default:                /* unknown option */
                        optlen = ip6_unknown_opt(opt, m,
                            opt - mtod(m, u_int8_t *));
                        if (optlen == -1) {
                                *mp = NULL;
                                return (IPPROTO_DONE);
                        }
                        optlen += 2;
                        break;
                }
        }

        *offp = off;
        *mp = m;
        return (dstopts->ip6d_nxt);

  bad:
        m_freem(m);
        *mp = NULL;
        return (IPPROTO_DONE);
}