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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_GRE_H
#define __LINUX_GRE_H
#include <linux/skbuff.h>
#include <net/ip_tunnels.h>
struct gre_base_hdr {
__be16 flags;
__be16 protocol;
} __packed;
struct gre_full_hdr {
struct gre_base_hdr fixed_header;
__be16 csum;
__be16 reserved1;
__be32 key;
__be32 seq;
} __packed;
#define GRE_HEADER_SECTION 4
#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);
};
int gre_add_protocol(const struct gre_protocol *proto, u8 version);
int gre_del_protocol(const struct gre_protocol *proto, u8 version);
struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
u8 name_assign_type);
int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
bool *csum_err, __be16 proto, int nhs);
bool is_gretap_dev(const struct net_device *dev);
bool is_ip6gretap_dev(const struct net_device *dev);
static inline int 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 gre_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;
}
static inline __sum16 gre_checksum(struct sk_buff *skb)
{
__wsum csum;
if (skb->ip_summed == CHECKSUM_PARTIAL)
csum = lco_csum(skb);
else
csum = skb_checksum(skb, 0, skb->len, 0);
return csum_fold(csum);
}
static inline void gre_build_header(struct sk_buff *skb, int hdr_len,
__be16 flags, __be16 proto,
__be32 key, __be32 seq)
{
struct gre_base_hdr *greh;
skb_push(skb, hdr_len);
skb_set_inner_protocol(skb, proto);
skb_reset_transport_header(skb);
greh = (struct gre_base_hdr *)skb->data;
greh->flags = gre_tnl_flags_to_gre_flags(flags);
greh->protocol = proto;
if (flags & (TUNNEL_KEY | TUNNEL_CSUM | TUNNEL_SEQ)) {
__be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4);
if (flags & TUNNEL_SEQ) {
*ptr = seq;
ptr--;
}
if (flags & TUNNEL_KEY) {
*ptr = key;
ptr--;
}
if (flags & TUNNEL_CSUM &&
!(skb_shinfo(skb)->gso_type &
(SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) {
*ptr = 0;
*(__sum16 *)ptr = gre_checksum(skb);
}
}
}
#endif
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