linux/include/net/erspan.h

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#ifndef __LINUX_ERSPAN_H
#define __LINUX_ERSPAN_H
/*
* GRE header for ERSPAN encapsulation (8 octets [34:41]) -- 8 bytes
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |0|0|0|1|0|00000|000000000|00000| Protocol Type for ERSPAN |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Sequence Number (increments per packet per session) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* Note that in the above GRE header [RFC1701] out of the C, R, K, S,
* s, Recur, Flags, Version fields only S (bit 03) is set to 1. The
* other fields are set to zero, so only a sequence number follows.
*
* ERSPAN Type II header (8 octets [42:49])
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Ver | VLAN | COS | En|T| Session ID |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Reserved | Index |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* GRE proto ERSPAN type II = 0x88BE, type III = 0x22EB
*/
#define ERSPAN_VERSION 0x1
#define VER_MASK 0xf000
#define VLAN_MASK 0x0fff
#define COS_MASK 0xe000
#define EN_MASK 0x1800
#define T_MASK 0x0400
#define ID_MASK 0x03ff
#define INDEX_MASK 0xfffff
enum erspan_encap_type {
ERSPAN_ENCAP_NOVLAN = 0x0, /* originally without VLAN tag */
ERSPAN_ENCAP_ISL = 0x1, /* originally ISL encapsulated */
ERSPAN_ENCAP_8021Q = 0x2, /* originally 802.1Q encapsulated */
ERSPAN_ENCAP_INFRAME = 0x3, /* VLAN tag perserved in frame */
};
struct erspan_metadata {
__be32 index; /* type II */
};
struct erspanhdr {
__be16 ver_vlan;
#define VER_OFFSET 12
__be16 session_id;
#define COS_OFFSET 13
#define EN_OFFSET 11
#define T_OFFSET 10
struct erspan_metadata md;
};
static inline u8 tos_to_cos(u8 tos)
{
u8 dscp, cos;
dscp = tos >> 2;
cos = dscp >> 3;
return cos;
}
static inline void erspan_build_header(struct sk_buff *skb,
__be32 id, u32 index,
bool truncate, bool is_ipv4)
{
struct ethhdr *eth = eth_hdr(skb);
enum erspan_encap_type enc_type;
struct erspanhdr *ershdr;
struct qtag_prefix {
__be16 eth_type;
__be16 tci;
} *qp;
u16 vlan_tci = 0;
u8 tos;
tos = is_ipv4 ? ip_hdr(skb)->tos :
(ipv6_hdr(skb)->priority << 4) +
(ipv6_hdr(skb)->flow_lbl[0] >> 4);
enc_type = ERSPAN_ENCAP_NOVLAN;
/* If mirrored packet has vlan tag, extract tci and
* perserve vlan header in the mirrored frame.
*/
if (eth->h_proto == htons(ETH_P_8021Q)) {
qp = (struct qtag_prefix *)(skb->data + 2 * ETH_ALEN);
vlan_tci = ntohs(qp->tci);
enc_type = ERSPAN_ENCAP_INFRAME;
}
skb_push(skb, sizeof(*ershdr));
ershdr = (struct erspanhdr *)skb->data;
memset(ershdr, 0, sizeof(*ershdr));
ershdr->ver_vlan = htons((vlan_tci & VLAN_MASK) |
(ERSPAN_VERSION << VER_OFFSET));
ershdr->session_id = htons((u16)(ntohl(id) & ID_MASK) |
((tos_to_cos(tos) << COS_OFFSET) & COS_MASK) |
(enc_type << EN_OFFSET & EN_MASK) |
((truncate << T_OFFSET) & T_MASK));
ershdr->md.index = htonl(index & INDEX_MASK);
}
#endif