1 #ifndef __LINUX_GRE_H 2 #define __LINUX_GRE_H 3 4 #include <linux/skbuff.h> 5 #include <net/ip_tunnels.h> 6 7 struct gre_base_hdr { 8 __be16 flags; 9 __be16 protocol; 10 }; 11 #define GRE_HEADER_SECTION 4 12 13 #define GREPROTO_CISCO 0 14 #define GREPROTO_PPTP 1 15 #define GREPROTO_MAX 2 16 #define GRE_IP_PROTO_MAX 2 17 18 struct gre_protocol { 19 int (*handler)(struct sk_buff *skb); 20 void (*err_handler)(struct sk_buff *skb, u32 info); 21 }; 22 23 int gre_add_protocol(const struct gre_protocol *proto, u8 version); 24 int gre_del_protocol(const struct gre_protocol *proto, u8 version); 25 26 struct net_device *gretap_fb_dev_create(struct net *net, const char *name, 27 u8 name_assign_type); 28 int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, 29 bool *csum_err, __be16 proto, int nhs); 30 31 static inline int gre_calc_hlen(__be16 o_flags) 32 { 33 int addend = 4; 34 35 if (o_flags & TUNNEL_CSUM) 36 addend += 4; 37 if (o_flags & TUNNEL_KEY) 38 addend += 4; 39 if (o_flags & TUNNEL_SEQ) 40 addend += 4; 41 return addend; 42 } 43 44 static inline __be16 gre_flags_to_tnl_flags(__be16 flags) 45 { 46 __be16 tflags = 0; 47 48 if (flags & GRE_CSUM) 49 tflags |= TUNNEL_CSUM; 50 if (flags & GRE_ROUTING) 51 tflags |= TUNNEL_ROUTING; 52 if (flags & GRE_KEY) 53 tflags |= TUNNEL_KEY; 54 if (flags & GRE_SEQ) 55 tflags |= TUNNEL_SEQ; 56 if (flags & GRE_STRICT) 57 tflags |= TUNNEL_STRICT; 58 if (flags & GRE_REC) 59 tflags |= TUNNEL_REC; 60 if (flags & GRE_VERSION) 61 tflags |= TUNNEL_VERSION; 62 63 return tflags; 64 } 65 66 static inline __be16 gre_tnl_flags_to_gre_flags(__be16 tflags) 67 { 68 __be16 flags = 0; 69 70 if (tflags & TUNNEL_CSUM) 71 flags |= GRE_CSUM; 72 if (tflags & TUNNEL_ROUTING) 73 flags |= GRE_ROUTING; 74 if (tflags & TUNNEL_KEY) 75 flags |= GRE_KEY; 76 if (tflags & TUNNEL_SEQ) 77 flags |= GRE_SEQ; 78 if (tflags & TUNNEL_STRICT) 79 flags |= GRE_STRICT; 80 if (tflags & TUNNEL_REC) 81 flags |= GRE_REC; 82 if (tflags & TUNNEL_VERSION) 83 flags |= GRE_VERSION; 84 85 return flags; 86 } 87 88 static inline __sum16 gre_checksum(struct sk_buff *skb) 89 { 90 __wsum csum; 91 92 if (skb->ip_summed == CHECKSUM_PARTIAL) 93 csum = lco_csum(skb); 94 else 95 csum = skb_checksum(skb, 0, skb->len, 0); 96 return csum_fold(csum); 97 } 98 99 static inline void gre_build_header(struct sk_buff *skb, int hdr_len, 100 __be16 flags, __be16 proto, 101 __be32 key, __be32 seq) 102 { 103 struct gre_base_hdr *greh; 104 105 skb_push(skb, hdr_len); 106 107 skb_reset_transport_header(skb); 108 greh = (struct gre_base_hdr *)skb->data; 109 greh->flags = gre_tnl_flags_to_gre_flags(flags); 110 greh->protocol = proto; 111 112 if (flags & (TUNNEL_KEY | TUNNEL_CSUM | TUNNEL_SEQ)) { 113 __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4); 114 115 if (flags & TUNNEL_SEQ) { 116 *ptr = seq; 117 ptr--; 118 } 119 if (flags & TUNNEL_KEY) { 120 *ptr = key; 121 ptr--; 122 } 123 if (flags & TUNNEL_CSUM && 124 !(skb_shinfo(skb)->gso_type & 125 (SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) { 126 *ptr = 0; 127 *(__sum16 *)ptr = gre_checksum(skb); 128 } 129 } 130 } 131 132 #endif 133