include/net/gre.h

   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);
  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