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vlan: Add function to retrieve EtherType from vlan packets. 

Depending on how a packet is vlan tagged (i.e. hardware accelerated or
not), the encapsulated protocol is stored in different locations.  This
provides a consistent method of accessing that protocol, which is needed
by drivers, security checks, etc.

Signed-off-by: Hao Zheng <hzheng@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Hao Zheng 2010-11-11 13:47:57 +00:00 committed by David S. Miller
parent 167c25e4c5
commit 0a85df0046
1 changed files with 25 additions and 0 deletions
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25
include/linux/if_vlan.h
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@ -339,6 +339,31 @@ static inline int vlan_get_tag(const struct sk_buff *skb, u16 *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;
}
#endif /* __KERNEL__ */
/* VLAN IOCTLs are found in sockios.h */