include/linux/netfilter_ipv4/ip_conntrack_proto_gre.h

   1 #ifndef _CONNTRACK_PROTO_GRE_H
   2 #define _CONNTRACK_PROTO_GRE_H
   3 #include <asm/byteorder.h>
   4
   5 /* GRE PROTOCOL HEADER */
   6
   7 /* GRE Version field */
   8 #define GRE_VERSION_1701        0x0
   9 #define GRE_VERSION_PPTP        0x1
  10
  11 /* GRE Protocol field */
  12 #define GRE_PROTOCOL_PPTP       0x880B
  13
  14 /* GRE Flags */
  15 #define GRE_FLAG_C              0x80
  16 #define GRE_FLAG_R              0x40
  17 #define GRE_FLAG_K              0x20
  18 #define GRE_FLAG_S              0x10
  19 #define GRE_FLAG_A              0x80
  20
  21 #define GRE_IS_C(f)     ((f)&GRE_FLAG_C)
  22 #define GRE_IS_R(f)     ((f)&GRE_FLAG_R)
  23 #define GRE_IS_K(f)     ((f)&GRE_FLAG_K)
  24 #define GRE_IS_S(f)     ((f)&GRE_FLAG_S)
  25 #define GRE_IS_A(f)     ((f)&GRE_FLAG_A)
  26
  27 /* GRE is a mess: Four different standards */
  28 struct gre_hdr {
  29 #if defined(__LITTLE_ENDIAN_BITFIELD)
  30         __u16   rec:3,
  31                 srr:1,
  32                 seq:1,
  33                 key:1,
  34                 routing:1,
  35                 csum:1,
  36                 version:3,
  37                 reserved:4,
  38                 ack:1;
  39 #elif defined(__BIG_ENDIAN_BITFIELD)
  40         __u16   csum:1,
  41                 routing:1,
  42                 key:1,
  43                 seq:1,
  44                 srr:1,
  45                 rec:3,
  46                 ack:1,
  47                 reserved:4,
  48                 version:3;
  49 #else
  50 #error "Adjust your <asm/byteorder.h> defines"
  51 #endif
  52         __be16  protocol;
  53 };
  54
  55 /* modified GRE header for PPTP */
  56 struct gre_hdr_pptp {
  57         __u8   flags;           /* bitfield */
  58         __u8   version;         /* should be GRE_VERSION_PPTP */
  59         __be16 protocol;        /* should be GRE_PROTOCOL_PPTP */
  60         __be16 payload_len;     /* size of ppp payload, not inc. gre header */
  61         __be16 call_id;         /* peer's call_id for this session */
  62         __be32 seq;             /* sequence number.  Present if S==1 */
  63         __be32 ack;             /* seq number of highest packet recieved by */
  64                                 /*  sender in this session */
  65 };
  66
  67
  68 /* this is part of ip_conntrack */
  69 struct ip_ct_gre {
  70         unsigned int stream_timeout;
  71         unsigned int timeout;
  72 };
  73
  74 #ifdef __KERNEL__
  75 struct ip_conntrack_expect;
  76 struct ip_conntrack;
  77
  78 /* structure for original <-> reply keymap */
  79 struct ip_ct_gre_keymap {
  80         struct list_head list;
  81
  82         struct ip_conntrack_tuple tuple;
  83 };
  84
  85 /* add new tuple->key_reply pair to keymap */
  86 int ip_ct_gre_keymap_add(struct ip_conntrack *ct,
  87                          struct ip_conntrack_tuple *t,
  88                          int reply);
  89
  90 /* delete keymap entries */
  91 void ip_ct_gre_keymap_destroy(struct ip_conntrack *ct);
  92
  93
  94 /* get pointer to gre key, if present */
  95 static inline __be32 *gre_key(struct gre_hdr *greh)
  96 {
  97         if (!greh->key)
  98                 return NULL;
  99         if (greh->csum || greh->routing)
 100                 return (__be32 *) (greh+sizeof(*greh)+4);
 101         return (__be32 *) (greh+sizeof(*greh));
 102 }
 103
 104 /* get pointer ot gre csum, if present */
 105 static inline __sum16 *gre_csum(struct gre_hdr *greh)
 106 {
 107         if (!greh->csum)
 108                 return NULL;
 109         return (__sum16 *) (greh+sizeof(*greh));
 110 }
 111
 112 #endif /* __KERNEL__ */
 113
 114 #endif /* _CONNTRACK_PROTO_GRE_H */