FreeBSD/Linux Kernel Cross Reference
sys/net/if_vlan_var.h

     /*
      * Copyright 1998 Massachusetts Institute of Technology
      *
      * Permission to use, copy, modify, and distribute this software and
      * its documentation for any purpose and without fee is hereby
      * granted, provided that both the above copyright notice and this
      * permission notice appear in all copies, that both the above
      * copyright notice and this permission notice appear in all
      * supporting documentation, and that the name of M.I.T. not be used
     * in advertising or publicity pertaining to distribution of the
     * software without specific, written prior permission.  M.I.T. makes
     * no representations about the suitability of this software for any
     * purpose.  It is provided "as is" without express or implied
     * warranty.
     * 
     * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
     * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
     * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
     * SHALL M.I.T. 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.
     *
     * $FreeBSD: releng/5.1/sys/net/if_vlan_var.h 112168 2003-03-13 00:30:31Z mux $
     */
    
    #ifndef _NET_IF_VLAN_VAR_H_
    #define _NET_IF_VLAN_VAR_H_     1
    
    struct  ether_vlan_header {
            u_char  evl_dhost[ETHER_ADDR_LEN];
            u_char  evl_shost[ETHER_ADDR_LEN];
            u_int16_t evl_encap_proto;
            u_int16_t evl_tag;
            u_int16_t evl_proto;
    };
    
    #define EVL_VLANOFTAG(tag) ((tag) & 4095)
    #define EVL_PRIOFTAG(tag) (((tag) >> 13) & 7)
    
    /* sysctl(3) tags, for compatibility purposes */
    #define VLANCTL_PROTO   1
    #define VLANCTL_MAX     2
    
    /*
     * Configuration structure for SIOCSETVLAN and SIOCGETVLAN ioctls.
     */
    struct  vlanreq {
            char    vlr_parent[IFNAMSIZ];
            u_short vlr_tag;
    };
    #define SIOCSETVLAN     SIOCSIFGENERIC
    #define SIOCGETVLAN     SIOCGIFGENERIC
    
    #ifdef _KERNEL
    /*
     * Drivers that are capable of adding and removing the VLAN header
     * in hardware indicate they support this by marking IFCAP_VLAN_HWTAGGING
     * in if_capabilities.  Drivers for hardware that is also capable
     * of handling larger MTU's that may include a software-appended
     * VLAN header w/o lowering the normal MTU should mark IFCAP_VLA_MTU
     * in if_capabilities; this notfies the VLAN code it can leave the
     * MTU on the vlan interface at the normal setting.
     */
    
    /*
     * Drivers that support hardware VLAN tagging pass a packet's tag
     * up through the stack by appending a packet tag with this value.
     * Output is handled likewise, the driver must locate the packet
     * tag to extract the VLAN tag.  The following macros are used to
     * do this work.  On input, do:
     *
     *      VLAN_INPUT_TAG(ifp, m, tag,);
     *
     * to mark the packet m with the specified VLAN tag.  The last
     * parameter provides code to execute in case of an error.  On
     * output the driver should check ifnet to see if any VLANs are
     * in use and only then check for a packet tag; this is done with:
     *
     *      struct m_tag *mtag;
     *      mtag = VLAN_OUTPUT_TAG(ifp, m);
     *      if (mtag != NULL) {
     *              ... = VLAN_TAG_VALUE(mtag);
     *              ... pass tag to hardware ...
     *      }
     *
     * Note that a driver must indicate it supports hardware VLAN
     * tagging by marking IFCAP_VLAN_HWTAGGING in if_capabilities.
     */
    #define MTAG_VLAN       1035328035
    #define MTAG_VLAN_TAG   0               /* tag of VLAN interface */
    
    #define VLAN_INPUT_TAG(_ifp, _m, _t, _errcase) do {             \
            struct m_tag *mtag;                                     \
           mtag = m_tag_alloc(MTAG_VLAN, MTAG_VLAN_TAG,            \
                              sizeof (u_int), M_NOWAIT);           \
           if (mtag == NULL) {                                     \
                   (_ifp)->if_ierrors++;                           \
                   m_freem(_m);                                    \
                   _errcase;                                       \
           }                                                       \
           *(u_int *)(mtag+1) = (_t);                              \
           m_tag_prepend((_m), mtag);                              \
   } while (0)
   
   #define VLAN_OUTPUT_TAG(_ifp, _m)                               \
           ((_ifp)->if_nvlans != 0 ?                               \
                   m_tag_locate((_m), MTAG_VLAN, MTAG_VLAN_TAG, NULL) : NULL)
   #define VLAN_TAG_VALUE(_mt)     (*(u_int *)((_mt)+1))
   #endif /* _KERNEL */
   
   #endif /* _NET_IF_VLAN_VAR_H_ */

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