/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _NF_NAT_H
#define _NF_NAT_H

#include <linux/list.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter/nf_conntrack_pptp.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_extend.h>
#include <net/netfilter/nf_conntrack_tuple.h>
#include <uapi/linux/netfilter/nf_nat.h>

enum nf_nat_manip_type {
        NF_NAT_MANIP_SRC,
        NF_NAT_MANIP_DST
};

/* SRC manip occurs POST_ROUTING or LOCAL_IN */
#define HOOK2MANIP(hooknum) ((hooknum) != NF_INET_POST_ROUTING && \
                             (hooknum) != NF_INET_LOCAL_IN)

/* per conntrack: nat application helper private data */
union nf_conntrack_nat_help {
        /* insert nat helper private data here */
#if IS_ENABLED(CONFIG_NF_NAT_PPTP)
        struct nf_nat_pptp nat_pptp_info;
#endif
};

/* The structure embedded in the conntrack structure. */
struct nf_conn_nat {
        union nf_conntrack_nat_help help;
#if IS_ENABLED(CONFIG_NF_NAT_MASQUERADE)
        int masq_index;
#endif
};

/* Set up the info structure to map into this range. */
unsigned int nf_nat_setup_info(struct nf_conn *ct,
                               const struct nf_nat_range2 *range,
                               enum nf_nat_manip_type maniptype);

extern unsigned int nf_nat_alloc_null_binding(struct nf_conn *ct,
                                              unsigned int hooknum);

struct nf_conn_nat *nf_ct_nat_ext_add(struct nf_conn *ct);

static inline struct nf_conn_nat *nfct_nat(const struct nf_conn *ct)
{
#if IS_ENABLED(CONFIG_NF_NAT)
        return nf_ct_ext_find(ct, NF_CT_EXT_NAT);
#else
        return NULL;
#endif
}

static inline bool nf_nat_oif_changed(unsigned int hooknum,
                                      enum ip_conntrack_info ctinfo,
                                      struct nf_conn_nat *nat,
                                      const struct net_device *out)
{
#if IS_ENABLED(CONFIG_NF_NAT_MASQUERADE)
        return nat && nat->masq_index && hooknum == NF_INET_POST_ROUTING &&
               CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL &&
               nat->masq_index != out->ifindex;
#else
        return false;
#endif
}

int nf_nat_register_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
                       const struct nf_hook_ops *nat_ops, unsigned int ops_count);
void nf_nat_unregister_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
                          unsigned int ops_count);

unsigned int nf_nat_packet(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
                           unsigned int hooknum, struct sk_buff *skb);

unsigned int nf_nat_manip_pkt(struct sk_buff *skb, struct nf_conn *ct,
                              enum nf_nat_manip_type mtype,
                              enum ip_conntrack_dir dir);
void nf_nat_csum_recalc(struct sk_buff *skb,
                        u8 nfproto, u8 proto, void *data, __sum16 *check,
                        int datalen, int oldlen);

int nf_nat_icmp_reply_translation(struct sk_buff *skb, struct nf_conn *ct,
                                  enum ip_conntrack_info ctinfo,
                                  unsigned int hooknum);

int nf_nat_icmpv6_reply_translation(struct sk_buff *skb, struct nf_conn *ct,
                                    enum ip_conntrack_info ctinfo,
                                    unsigned int hooknum, unsigned int hdrlen);

int nf_nat_ipv4_register_fn(struct net *net, const struct nf_hook_ops *ops);
void nf_nat_ipv4_unregister_fn(struct net *net, const struct nf_hook_ops *ops);

int nf_nat_ipv6_register_fn(struct net *net, const struct nf_hook_ops *ops);
void nf_nat_ipv6_unregister_fn(struct net *net, const struct nf_hook_ops *ops);

int nf_nat_inet_register_fn(struct net *net, const struct nf_hook_ops *ops);
void nf_nat_inet_unregister_fn(struct net *net, const struct nf_hook_ops *ops);

unsigned int
nf_nat_inet_fn(void *priv, struct sk_buff *skb,
               const struct nf_hook_state *state);

int nf_ct_nat(struct sk_buff *skb, struct nf_conn *ct,
              enum ip_conntrack_info ctinfo, int *action,
              const struct nf_nat_range2 *range, bool commit);

static inline int nf_nat_initialized(const struct nf_conn *ct,
                                     enum nf_nat_manip_type manip)
{
        if (manip == NF_NAT_MANIP_SRC)
                return ct->status & IPS_SRC_NAT_DONE;
        else
                return ct->status & IPS_DST_NAT_DONE;
}
#endif