root/include/net/netfilter/nf_conntrack_synproxy.h

DEFINITIONS

1. nfct_synproxy
2. nfct_synproxy_ext_add
3. synproxy_pernet

#ifndef _NF_CONNTRACK_SYNPROXY_H
#define _NF_CONNTRACK_SYNPROXY_H

#include <net/netns/generic.h>

struct nf_conn_synproxy {
        u32     isn;
        u32     its;
        u32     tsoff;
};

static inline struct nf_conn_synproxy *nfct_synproxy(const struct nf_conn *ct)
{
#if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY)
        return nf_ct_ext_find(ct, NF_CT_EXT_SYNPROXY);
#else
        return NULL;
#endif
}

static inline struct nf_conn_synproxy *nfct_synproxy_ext_add(struct nf_conn *ct)
{
#if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY)
        return nf_ct_ext_add(ct, NF_CT_EXT_SYNPROXY, GFP_ATOMIC);
#else
        return NULL;
#endif
}

struct synproxy_stats {
        unsigned int                    syn_received;
        unsigned int                    cookie_invalid;
        unsigned int                    cookie_valid;
        unsigned int                    cookie_retrans;
        unsigned int                    conn_reopened;
};

struct synproxy_net {
        struct nf_conn                  *tmpl;
        struct synproxy_stats __percpu  *stats;
};

extern int synproxy_net_id;
static inline struct synproxy_net *synproxy_pernet(struct net *net)
{
        return net_generic(net, synproxy_net_id);
}

struct synproxy_options {
        u8                              options;
        u8                              wscale;
        u16                             mss;
        u32                             tsval;
        u32                             tsecr;
};

struct tcphdr;
struct xt_synproxy_info;
bool synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
                            const struct tcphdr *th,
                            struct synproxy_options *opts);
unsigned int synproxy_options_size(const struct synproxy_options *opts);
void synproxy_build_options(struct tcphdr *th,
                            const struct synproxy_options *opts);

void synproxy_init_timestamp_cookie(const struct xt_synproxy_info *info,
                                    struct synproxy_options *opts);
void synproxy_check_timestamp_cookie(struct synproxy_options *opts);

unsigned int synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff,
                                    struct tcphdr *th, struct nf_conn *ct,
                                    enum ip_conntrack_info ctinfo,
                                    const struct nf_conn_synproxy *synproxy);

#endif /* _NF_CONNTRACK_SYNPROXY_H */