-/*
- * The GRE header is composed of a series of sections: a base and then a variable
- * number of options.
- */
-#define GRE_HEADER_SECTION 4
-
-struct gre_base_hdr {
- __be16 flags;
- __be16 protocol;
-};
-
-static int gre_hdr_len(const struct ovs_key_ipv4_tunnel *tun_key)
-{
- int len = GRE_HEADER_SECTION;
-
- if (tun_key->tun_flags & OVS_TNL_F_KEY)
- len += GRE_HEADER_SECTION;
- if (tun_key->tun_flags & OVS_TNL_F_CSUM)
- len += GRE_HEADER_SECTION;
- return len;
-}
-
-static int gre64_hdr_len(const struct ovs_key_ipv4_tunnel *tun_key)
-{
- /* Set key for GRE64 tunnels, even when key if is zero. */
- int len = GRE_HEADER_SECTION + /* GRE Hdr */
- GRE_HEADER_SECTION + /* GRE Key */
- GRE_HEADER_SECTION; /* GRE SEQ */
-
- if (tun_key->tun_flags & OVS_TNL_F_CSUM)
- len += GRE_HEADER_SECTION;
-
- return len;
-}
-
-/* Returns the least-significant 32 bits of a __be64. */
-static __be32 be64_get_low32(__be64 x)
-{
-#ifdef __BIG_ENDIAN
- return (__force __be32)x;
-#else
- return (__force __be32)((__force u64)x >> 32);
-#endif
-}
-
-static __be32 be64_get_high32(__be64 x)
-{
-#ifdef __BIG_ENDIAN
- return (__force __be32)((__force u64)x >> 32);
-#else
- return (__force __be32)x;
-#endif
-}
-
-static void __gre_build_header(struct sk_buff *skb,
- int tunnel_hlen,
- bool is_gre64)
-{
- const struct ovs_key_ipv4_tunnel *tun_key = OVS_CB(skb)->tun_key;
- __be32 *options = (__be32 *)(skb_network_header(skb) + tunnel_hlen
- - GRE_HEADER_SECTION);
- struct gre_base_hdr *greh = (struct gre_base_hdr *) skb_transport_header(skb);
- greh->protocol = htons(ETH_P_TEB);
- greh->flags = 0;
-
- /* Work backwards over the options so the checksum is last. */
- if (tun_key->tun_flags & OVS_TNL_F_KEY || is_gre64) {
- greh->flags |= GRE_KEY;
- if (is_gre64) {
- /* Set higher 32 bits to seq. */
- *options = be64_get_high32(tun_key->tun_id);
- options--;
- greh->flags |= GRE_SEQ;
- }
- *options = be64_get_low32(tun_key->tun_id);
- options--;
- }
-
- if (tun_key->tun_flags & OVS_TNL_F_CSUM) {
- greh->flags |= GRE_CSUM;
- *options = 0;
- *(__sum16 *)options = csum_fold(skb_checksum(skb,
- skb_transport_offset(skb),
- skb->len - skb_transport_offset(skb),
- 0));
- }
-}
-
-static void gre_build_header(const struct vport *vport,
- struct sk_buff *skb,
- int tunnel_hlen)
-{
- __gre_build_header(skb, tunnel_hlen, false);
-}
-
-static void gre64_build_header(const struct vport *vport,
- struct sk_buff *skb,
- int tunnel_hlen)
-{
- __gre_build_header(skb, tunnel_hlen, true);
-}
-
-static __be64 key_to_tunnel_id(__be32 key, __be32 seq)
-{
-#ifdef __BIG_ENDIAN
- return (__force __be64)((__force u64)seq << 32 | (__force u32)key);
-#else
- return (__force __be64)((__force u64)key << 32 | (__force u32)seq);
-#endif
-}
-
-static int parse_header(struct iphdr *iph, __be16 *flags, __be64 *tun_id,
- bool *is_gre64)
-{
- /* IP and ICMP protocol handlers check that the IHL is valid. */
- struct gre_base_hdr *greh = (struct gre_base_hdr *)((u8 *)iph + (iph->ihl << 2));
- __be32 *options = (__be32 *)(greh + 1);
- int hdr_len;
-
- *flags = greh->flags;
-
- if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
- return -EINVAL;
-
- if (unlikely(greh->protocol != htons(ETH_P_TEB)))
- return -EINVAL;
-
- hdr_len = GRE_HEADER_SECTION;
-
- if (greh->flags & GRE_CSUM) {
- hdr_len += GRE_HEADER_SECTION;
- options++;
- }
-
- if (greh->flags & GRE_KEY) {
- __be32 seq;
- __be32 gre_key;
-
- gre_key = *options;
- hdr_len += GRE_HEADER_SECTION;
- options++;