/*      $NetBSD: if_agrether_hash.c,v 1.4 2017/09/26 07:42:06 knakahara Exp $   */

/*-
* Copyright (c)2005 YAMAMOTO Takashi,
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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: if_agrether_hash.c,v 1.4 2017/09/26 07:42:06 knakahara Exp $");

#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/hash.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_ether.h>
#include <net/if_vlanvar.h>

#include <net/agr/if_agrethervar.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>

#define HASH(p, l, h)   hash32_buf((p), (l), (h))

static const void *agr_m_extract(struct mbuf *, int, int, void *);

static const void *
agr_m_extract(struct mbuf *m, int off, int len, void *buf)
{
       const void *result;

       KASSERT((m->m_flags & M_PKTHDR) != 0);

       if (m->m_pkthdr.len < off + len) {
               result = NULL;
       } else if (m->m_len >= off + len) {
               result = mtod(m, char *) + off;
       } else {
               m_copydata(m, off, len, buf);
               result = buf;
       }

       return result;
}

uint32_t
agrether_hashmbuf(struct agr_softc *sc, struct mbuf *m)
{
       struct ether_header eh_store;
       const struct ether_header *eh;
       uint32_t hash = HASH32_BUF_INIT;
       int off = 0;
       uint16_t tci;
       uint16_t etype;

       eh = agr_m_extract(m, off, sizeof(*eh), &eh_store);
       if (eh == NULL) {
               return hash;
       }

       hash = HASH(&eh->ether_dhost, sizeof(eh->ether_dhost), hash);
       hash = HASH(&eh->ether_shost, sizeof(eh->ether_shost), hash);
       etype = eh->ether_type;

       if (etype == htobe16(ETHERTYPE_VLAN)) {
               struct ether_vlan_header vlanhdr_store;
               const struct ether_vlan_header *vlanhdr;

               vlanhdr = agr_m_extract(m, off, sizeof(*vlanhdr),
                   &vlanhdr_store);
               if (vlanhdr == NULL) {
                       return hash;
               }

               tci = vlanhdr->evl_tag;
               etype = vlanhdr->evl_proto;
               off += sizeof(*vlanhdr) - sizeof(*eh);
       } else if (vlan_has_tag(m)) {
               tci = htole16(vlan_get_tag(m));
       } else {
               tci = 0;
       }
       hash = HASH(&tci, sizeof(tci), hash);

       off += sizeof(*eh);
       if (etype == htobe16(ETHERTYPE_IP)) {
               struct ip ip_store;
               const struct ip *ip;

               ip = agr_m_extract(m, off, sizeof(*ip), &ip_store);
               if (ip == NULL) {
                       return hash;
               }

               hash = HASH(&ip->ip_src, sizeof(ip->ip_src), hash);
               hash = HASH(&ip->ip_dst, sizeof(ip->ip_dst), hash);
               hash = HASH(&ip->ip_p, sizeof(ip->ip_p), hash);

               /* use port numbers for tcp and udp? */

       } else if (etype == htobe16(ETHERTYPE_IPV6)) {
               struct ip6_hdr ip6_store;
               const struct ip6_hdr *ip6;
               uint32_t flowlabel;

               ip6 = agr_m_extract(m, off, sizeof(*ip6), &ip6_store);
               if (ip6 == NULL) {
                       return hash;
               }

               hash = HASH(&ip6->ip6_src, sizeof(ip6->ip6_src), hash);
               hash = HASH(&ip6->ip6_dst, sizeof(ip6->ip6_dst), hash);
               /* hash = HASH(&ip6->ip6_nxt, sizeof(ip6->ip6_nxt), hash); */

               flowlabel = ip6->ip6_flow & IPV6_FLOWLABEL_MASK;
               hash = HASH(&flowlabel, sizeof(flowlabel), hash);

               /* use port numbers for tcp and udp? */
       }

       return hash;
}