if_vlan.h

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/*
 * VLAN     An implementation of 802.1Q VLAN tagging.
 *
 * Authors: Ben Greear <[email protected]>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 */
#ifndef _LINUX_IF_VLAN_H_
#define _LINUX_IF_VLAN_H_

#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.h>
#include <linux/bug.h>
#include <uapi/linux/if_vlan.h>

#define VLAN_HLEN   4       /* The additional bytes required by VLAN
                     * (in addition to the Ethernet header)
                     */
#define VLAN_ETH_HLEN   18      /* Total octets in header.   */
#define VLAN_ETH_ZLEN   64      /* Min. octets in frame sans FCS */

/*
 * According to 802.3ac, the packet can be 4 bytes longer. --Klika Jan
 */
#define VLAN_ETH_DATA_LEN   1500    /* Max. octets in payload    */
#define VLAN_ETH_FRAME_LEN  1518    /* Max. octets in frame sans FCS */

/*
 *  struct vlan_hdr - vlan header
 *  @h_vlan_TCI: priority and VLAN ID
 *  @h_vlan_encapsulated_proto: packet type ID or len
 */
struct vlan_hdr {
    __be16  h_vlan_TCI;
    __be16  h_vlan_encapsulated_proto;
};

struct vlan_ethhdr {
    unsigned char   h_dest[ETH_ALEN];
    unsigned char   h_source[ETH_ALEN];
    __be16      h_vlan_proto;
    __be16      h_vlan_TCI;
    __be16      h_vlan_encapsulated_proto;
};

#include <linux/skbuff.h>

static inline struct vlan_ethhdr *vlan_eth_hdr(const struct sk_buff *skb)
{
    return (struct vlan_ethhdr *)skb_mac_header(skb);
}

#define VLAN_PRIO_MASK      0xe000 /* Priority Code Point */
#define VLAN_PRIO_SHIFT     13
#define VLAN_CFI_MASK       0x1000 /* Canonical Format Indicator */
#define VLAN_TAG_PRESENT    VLAN_CFI_MASK
#define VLAN_VID_MASK       0x0fff /* VLAN Identifier */
#define VLAN_N_VID      4096

/* found in socket.c */
extern void vlan_ioctl_set(int (*hook)(struct net *, void __user *));

static inline int is_vlan_dev(struct net_device *dev)
{
        return dev->priv_flags & IFF_802_1Q_VLAN;
}

#define vlan_tx_tag_present(__skb)  ((__skb)->vlan_tci & VLAN_TAG_PRESENT)
#define vlan_tx_nonzero_tag_present(__skb) \
    (vlan_tx_tag_present(__skb) && ((__skb)->vlan_tci & VLAN_VID_MASK))
#define vlan_tx_tag_get(__skb)      ((__skb)->vlan_tci & ~VLAN_TAG_PRESENT)

#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)

extern struct net_device *__vlan_find_dev_deep(struct net_device *real_dev,
                           u16 vlan_id);
extern struct net_device *vlan_dev_real_dev(const struct net_device *dev);
extern u16 vlan_dev_vlan_id(const struct net_device *dev);

extern bool vlan_do_receive(struct sk_buff **skb);
extern struct sk_buff *vlan_untag(struct sk_buff *skb);

extern int vlan_vid_add(struct net_device *dev, unsigned short vid);
extern void vlan_vid_del(struct net_device *dev, unsigned short vid);

extern int vlan_vids_add_by_dev(struct net_device *dev,
                const struct net_device *by_dev);
extern void vlan_vids_del_by_dev(struct net_device *dev,
                 const struct net_device *by_dev);

extern bool vlan_uses_dev(const struct net_device *dev);
#else
static inline struct net_device *
__vlan_find_dev_deep(struct net_device *real_dev, u16 vlan_id)
{
    return NULL;
}

static inline struct net_device *vlan_dev_real_dev(const struct net_device *dev)
{
    BUG();
    return NULL;
}

static inline u16 vlan_dev_vlan_id(const struct net_device *dev)
{
    BUG();
    return 0;
}

static inline bool vlan_do_receive(struct sk_buff **skb)
{
    return false;
}

static inline struct sk_buff *vlan_untag(struct sk_buff *skb)
{
    return skb;
}

static inline int vlan_vid_add(struct net_device *dev, unsigned short vid)
{
    return 0;
}

static inline void vlan_vid_del(struct net_device *dev, unsigned short vid)
{
}

static inline int vlan_vids_add_by_dev(struct net_device *dev,
                       const struct net_device *by_dev)
{
    return 0;
}

static inline void vlan_vids_del_by_dev(struct net_device *dev,
                    const struct net_device *by_dev)
{
}

static inline bool vlan_uses_dev(const struct net_device *dev)
{
    return false;
}
#endif

static inline struct sk_buff *vlan_insert_tag(struct sk_buff *skb, u16 vlan_tci)
{
    struct vlan_ethhdr *veth;

    if (skb_cow_head(skb, VLAN_HLEN) < 0) {
        kfree_skb(skb);
        return NULL;
    }
    veth = (struct vlan_ethhdr *)skb_push(skb, VLAN_HLEN);

    /* Move the mac addresses to the beginning of the new header. */
    memmove(skb->data, skb->data + VLAN_HLEN, 2 * ETH_ALEN);
    skb->mac_header -= VLAN_HLEN;

    /* first, the ethernet type */
    veth->h_vlan_proto = htons(ETH_P_8021Q);

    /* now, the TCI */
    veth->h_vlan_TCI = htons(vlan_tci);

    return skb;
}

static inline struct sk_buff *__vlan_put_tag(struct sk_buff *skb, u16 vlan_tci)
{
    skb = vlan_insert_tag(skb, vlan_tci);
    if (skb)
        skb->protocol = htons(ETH_P_8021Q);
    return skb;
}

static inline struct sk_buff *__vlan_hwaccel_put_tag(struct sk_buff *skb,
                             u16 vlan_tci)
{
    skb->vlan_tci = VLAN_TAG_PRESENT | vlan_tci;
    return skb;
}

#define HAVE_VLAN_PUT_TAG

static inline struct sk_buff *vlan_put_tag(struct sk_buff *skb, u16 vlan_tci)
{
    if (skb->dev->features & NETIF_F_HW_VLAN_TX) {
        return __vlan_hwaccel_put_tag(skb, vlan_tci);
    } else {
        return __vlan_put_tag(skb, vlan_tci);
    }
}

static inline int __vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
{
    struct vlan_ethhdr *veth = (struct vlan_ethhdr *)skb->data;

    if (veth->h_vlan_proto != htons(ETH_P_8021Q)) {
        return -EINVAL;
    }

    *vlan_tci = ntohs(veth->h_vlan_TCI);
    return 0;
}

static inline int __vlan_hwaccel_get_tag(const struct sk_buff *skb,
                     u16 *vlan_tci)
{
    if (vlan_tx_tag_present(skb)) {
        *vlan_tci = vlan_tx_tag_get(skb);
        return 0;
    } else {
        *vlan_tci = 0;
        return -EINVAL;
    }
}

#define HAVE_VLAN_GET_TAG

static inline int vlan_get_tag(const struct sk_buff *skb, u16 *vlan_tci)
{
    if (skb->dev->features & NETIF_F_HW_VLAN_TX) {
        return __vlan_hwaccel_get_tag(skb, vlan_tci);
    } else {
        return __vlan_get_tag(skb, vlan_tci);
    }
}

static inline __be16 vlan_get_protocol(const struct sk_buff *skb)
{
    __be16 protocol = 0;

    if (vlan_tx_tag_present(skb) ||
         skb->protocol != cpu_to_be16(ETH_P_8021Q))
        protocol = skb->protocol;
    else {
        __be16 proto, *protop;
        protop = skb_header_pointer(skb, offsetof(struct vlan_ethhdr,
                        h_vlan_encapsulated_proto),
                        sizeof(proto), &proto);
        if (likely(protop))
            protocol = *protop;
    }

    return protocol;
}

static inline void vlan_set_encap_proto(struct sk_buff *skb,
                    struct vlan_hdr *vhdr)
{
    __be16 proto;
    unsigned char *rawp;

    /*
     * Was a VLAN packet, grab the encapsulated protocol, which the layer
     * three protocols care about.
     */

    proto = vhdr->h_vlan_encapsulated_proto;
    if (ntohs(proto) >= 1536) {
        skb->protocol = proto;
        return;
    }

    rawp = skb->data;
    if (*(unsigned short *) rawp == 0xFFFF)
        /*
         * This is a magic hack to spot IPX packets. Older Novell
         * breaks the protocol design and runs IPX over 802.3 without
         * an 802.2 LLC layer. We look for FFFF which isn't a used
         * 802.2 SSAP/DSAP. This won't work for fault tolerant netware
         * but does for the rest.
         */
        skb->protocol = htons(ETH_P_802_3);
    else
        /*
         * Real 802.2 LLC
         */
        skb->protocol = htons(ETH_P_802_2);
}
#endif /* !(_LINUX_IF_VLAN_H_) */