root/include/net/gre.h

DEFINITIONS

1. gre_handle_offloads
2. ip_gre_calc_hlen
3. gre_flags_to_tnl_flags
4. tnl_flags_to_gre_flags

#ifndef __LINUX_GRE_H
#define __LINUX_GRE_H

#include <linux/skbuff.h>
#include <net/ip_tunnels.h>

#define GREPROTO_CISCO          0
#define GREPROTO_PPTP           1
#define GREPROTO_MAX            2
#define GRE_IP_PROTO_MAX        2

struct gre_protocol {
        int  (*handler)(struct sk_buff *skb);
        void (*err_handler)(struct sk_buff *skb, u32 info);
};

struct gre_base_hdr {
        __be16 flags;
        __be16 protocol;
};
#define GRE_HEADER_SECTION 4

int gre_add_protocol(const struct gre_protocol *proto, u8 version);
int gre_del_protocol(const struct gre_protocol *proto, u8 version);

struct gre_cisco_protocol {
        int (*handler)(struct sk_buff *skb, const struct tnl_ptk_info *tpi);
        int (*err_handler)(struct sk_buff *skb, u32 info,
                           const struct tnl_ptk_info *tpi);
        u8 priority;
};

int gre_cisco_register(struct gre_cisco_protocol *proto);
int gre_cisco_unregister(struct gre_cisco_protocol *proto);

void gre_build_header(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
                      int hdr_len);

static inline struct sk_buff *gre_handle_offloads(struct sk_buff *skb,
                                                  bool csum)
{
        return iptunnel_handle_offloads(skb, csum,
                                        csum ? SKB_GSO_GRE_CSUM : SKB_GSO_GRE);
}


static inline int ip_gre_calc_hlen(__be16 o_flags)
{
        int addend = 4;

        if (o_flags&TUNNEL_CSUM)
                addend += 4;
        if (o_flags&TUNNEL_KEY)
                addend += 4;
        if (o_flags&TUNNEL_SEQ)
                addend += 4;
        return addend;
}

static inline __be16 gre_flags_to_tnl_flags(__be16 flags)
{
        __be16 tflags = 0;

        if (flags & GRE_CSUM)
                tflags |= TUNNEL_CSUM;
        if (flags & GRE_ROUTING)
                tflags |= TUNNEL_ROUTING;
        if (flags & GRE_KEY)
                tflags |= TUNNEL_KEY;
        if (flags & GRE_SEQ)
                tflags |= TUNNEL_SEQ;
        if (flags & GRE_STRICT)
                tflags |= TUNNEL_STRICT;
        if (flags & GRE_REC)
                tflags |= TUNNEL_REC;
        if (flags & GRE_VERSION)
                tflags |= TUNNEL_VERSION;

        return tflags;
}

static inline __be16 tnl_flags_to_gre_flags(__be16 tflags)
{
        __be16 flags = 0;

        if (tflags & TUNNEL_CSUM)
                flags |= GRE_CSUM;
        if (tflags & TUNNEL_ROUTING)
                flags |= GRE_ROUTING;
        if (tflags & TUNNEL_KEY)
                flags |= GRE_KEY;
        if (tflags & TUNNEL_SEQ)
                flags |= GRE_SEQ;
        if (tflags & TUNNEL_STRICT)
                flags |= GRE_STRICT;
        if (tflags & TUNNEL_REC)
                flags |= GRE_REC;
        if (tflags & TUNNEL_VERSION)
                flags |= GRE_VERSION;

        return flags;
}

#endif