include/linux/if_vlan.h

/*
 * VLAN		An implementation of 802.1Q VLAN tagging.
 *
 * Authors:	Ben Greear <greearb@candelatech.com>
 *
 *		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 - vlan ethernet header (ethhdr + vlan_hdr)
 *	@h_dest: destination ethernet address
 *	@h_source: source ethernet address
 *	@h_vlan_proto: ethernet protocol (always 0x8100)
 *	@h_vlan_TCI: priority and VLAN ID
 *	@h_vlan_encapsulated_proto: packet type ID or len
 */
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

/**
 * vlan_insert_tag - regular VLAN tag inserting
 * @skb: skbuff to tag
 * @vlan_tci: VLAN TCI to insert
 *
 * Inserts the VLAN tag into @skb as part of the payload
 * Returns a VLAN tagged skb. If a new skb is created, @skb is freed.
 *
 * Following the skb_unshare() example, in case of error, the calling function
 * doesn't have to worry about freeing the original skb.
 *
 * Does not change skb->protocol so this function can be used during receive.
 */
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;
}

/**
 * __vlan_put_tag - regular VLAN tag inserting
 * @skb: skbuff to tag
 * @vlan_tci: VLAN TCI to insert
 *
 * Inserts the VLAN tag into @skb as part of the payload
 * Returns a VLAN tagged skb. If a new skb is created, @skb is freed.
 *
 * Following the skb_unshare() example, in case of error, the calling function
 * doesn't have to worry about freeing the original 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;
}

/**
 * __vlan_hwaccel_put_tag - hardware accelerated VLAN inserting
 * @skb: skbuff to tag
 * @vlan_tci: VLAN TCI to insert
 *
 * Puts the VLAN TCI in @skb->vlan_tci and lets the device do the rest
 */
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

/**
 * vlan_put_tag - inserts VLAN tag according to device features
 * @skb: skbuff to tag
 * @vlan_tci: VLAN TCI to insert
 *
 * Assumes skb->dev is the target that will xmit this frame.
 * Returns a VLAN tagged skb.
 */
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);
	}
}

/**
 * __vlan_get_tag - get the VLAN ID that is part of the payload
 * @skb: skbuff to query
 * @vlan_tci: buffer to store vlaue
 *
 * Returns error if the skb is not of VLAN type
 */
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;
}

/**
 * __vlan_hwaccel_get_tag - get the VLAN ID that is in @skb->cb[]
 * @skb: skbuff to query
 * @vlan_tci: buffer to store vlaue
 *
 * Returns error if @skb->vlan_tci is not set correctly
 */
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

/**
 * vlan_get_tag - get the VLAN ID from the skb
 * @skb: skbuff to query
 * @vlan_tci: buffer to store vlaue
 *
 * Returns error if the skb is not VLAN tagged
 */
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);
	}
}

/**
 * vlan_get_protocol - get protocol EtherType.
 * @skb: skbuff to query
 *
 * Returns the EtherType of the packet, regardless of whether it is
 * vlan encapsulated (normal or hardware accelerated) or not.
 */
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_) */