include/linux/netfilter_ipv4/ip_nat_helper.h

   1 #ifndef _IP_NAT_HELPER_H
   2 #define _IP_NAT_HELPER_H
   3 /* NAT protocol helper routines. */
   4
   5 #include <linux/netfilter_ipv4/ip_conntrack.h>
   6 #include <linux/module.h>
   7
   8 struct sk_buff;
   9
  10 /* Flags */
  11 /* NAT helper must be called on every packet (for TCP) */
  12 #define IP_NAT_HELPER_F_ALWAYS          0x01
  13
  14 struct ip_nat_helper
  15 {
  16         struct list_head list;          /* Internal use */
  17
  18         const char *name;               /* name of the module */
  19         unsigned char flags;            /* Flags (see above) */
  20         struct module *me;              /* pointer to self */
  21
  22         /* Mask of things we will help: vs. tuple from server */
  23         struct ip_conntrack_tuple tuple;
  24         struct ip_conntrack_tuple mask;
  25
  26         /* Helper function: returns verdict */
  27         unsigned int (*help)(struct ip_conntrack *ct,
  28                              struct ip_conntrack_expect *exp,
  29                              struct ip_nat_info *info,
  30                              enum ip_conntrack_info ctinfo,
  31                              unsigned int hooknum,
  32                              struct sk_buff **pskb);
  33
  34         /* Returns verdict and sets up NAT for this connection */
  35         unsigned int (*expect)(struct sk_buff **pskb,
  36                                unsigned int hooknum,
  37                                struct ip_conntrack *ct,
  38                                struct ip_nat_info *info);
  39 };
  40
  41 extern struct list_head helpers;
  42
  43 extern int ip_nat_helper_register(struct ip_nat_helper *me);
  44 extern void ip_nat_helper_unregister(struct ip_nat_helper *me);
  45
  46 /* These return true or false. */
  47 extern int ip_nat_mangle_tcp_packet(struct sk_buff **skb,
  48                                 struct ip_conntrack *ct,
  49                                 enum ip_conntrack_info ctinfo,
  50                                 unsigned int match_offset,
  51                                 unsigned int match_len,
  52                                 const char *rep_buffer,
  53                                 unsigned int rep_len);
  54 extern int ip_nat_mangle_udp_packet(struct sk_buff **skb,
  55                                 struct ip_conntrack *ct,
  56                                 enum ip_conntrack_info ctinfo,
  57                                 unsigned int match_offset,
  58                                 unsigned int match_len,
  59                                 const char *rep_buffer,
  60                                 unsigned int rep_len);
  61 extern int ip_nat_seq_adjust(struct sk_buff **pskb,
  62                              struct ip_conntrack *ct,
  63                              enum ip_conntrack_info ctinfo);
  64 #endif