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/*
* Copyright (c) 2007-2011 Nicira, Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA
*/
#ifndef VLAN_H
#define VLAN_H 1
#include <linux/if_vlan.h>
#include <linux/skbuff.h>
#include <linux/version.h>
/**
* DOC: VLAN tag manipulation.
*
* &struct sk_buff handling of VLAN tags has evolved over time:
*
* In 2.6.26 and earlier, VLAN tags did not have any generic representation in
* an skb, other than as a raw 802.1Q header inside the packet data.
*
* In 2.6.27 &struct sk_buff added a @vlan_tci member. Between 2.6.27 and
* 2.6.32, its value was the raw contents of the 802.1Q TCI field, or zero if
* no 802.1Q header was present. This worked OK except for the corner case of
* an 802.1Q header with an all-0-bits TCI, which could not be represented.
*
* In 2.6.33, @vlan_tci semantics changed. Now, if an 802.1Q header is
* present, then the VLAN_TAG_PRESENT bit is always set. This fixes the
* all-0-bits TCI corner case.
*
* For compatibility we emulate the 2.6.33+ behavior on earlier kernel
* versions. The client must not access @vlan_tci directly. Instead, use
* vlan_get_tci() to read it or vlan_set_tci() to write it, with semantics
* equivalent to those on 2.6.33+.
*/
static inline u16 vlan_get_tci(struct sk_buff *skb)
{
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,33)
if (skb->vlan_tci)
return skb->vlan_tci | VLAN_TAG_PRESENT;
#endif
return skb->vlan_tci;
}
static inline void vlan_set_tci(struct sk_buff *skb, u16 vlan_tci)
{
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,33)
vlan_tci &= ~VLAN_TAG_PRESENT;
#endif
skb->vlan_tci = vlan_tci;
}
#endif /* vlan.h */
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