/*      $OpenBSD: mpls_shim.c,v 1.8 2014/12/05 15:50:04 mpi Exp $       */

/*
 * Copyright (C) 1999, 2000 and 2001 AYAME Project, 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/param.h>
#include <sys/mbuf.h>
#include <sys/errno.h>
#include <sys/socket.h>
#include <sys/systm.h>

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

#include <netmpls/mpls.h>

struct mbuf *
mpls_shim_pop(struct mbuf *m)
{
        /* shaves off top shim header from mbuf */
        m_adj(m, sizeof(struct shim_hdr));

        /* catch-up next shim_hdr */
        if (m->m_len < sizeof(struct shim_hdr))
                if ((m = m_pullup(m, sizeof(struct shim_hdr))) == NULL)
                        return (NULL);

        /* return mbuf */
        return (m);
}

struct mbuf *
mpls_shim_swap(struct mbuf *m, struct rt_mpls *rt_mpls)
{
        struct shim_hdr *shim;

        /* pullup shim_hdr */
        if (m->m_len < sizeof(struct shim_hdr))
                if ((m = m_pullup(m, sizeof(struct shim_hdr))) == NULL)
                        return (NULL);
        shim = mtod(m, struct shim_hdr *);

        /* swap label */
        shim->shim_label &= ~MPLS_LABEL_MASK;
        shim->shim_label |= rt_mpls->mpls_label & MPLS_LABEL_MASK;

        /* swap exp : XXX exp override */
        {
                u_int32_t       t;

                shim->shim_label &= ~MPLS_EXP_MASK;
                t = rt_mpls->mpls_exp << MPLS_EXP_OFFSET;
                shim->shim_label |= htonl(t) & MPLS_EXP_MASK;
        }

        return (m);
}

struct mbuf *
mpls_shim_push(struct mbuf *m, struct rt_mpls *rt_mpls)
{
        struct shim_hdr *shim;

        M_PREPEND(m, sizeof(struct shim_hdr), M_DONTWAIT);
        if (m == NULL)
                return (NULL);

        shim = mtod(m, struct shim_hdr *);
        bzero((caddr_t)shim, sizeof(*shim));

        return (mpls_shim_swap(m, rt_mpls));
}