root/include/linux/netfilter/nf_conntrack_tcp.h

INCLUDED FROM

#ifndef _NF_CONNTRACK_TCP_H
#define _NF_CONNTRACK_TCP_H
/* TCP tracking. */

/* This is exposed to userspace (ctnetlink) */
enum tcp_conntrack {
        TCP_CONNTRACK_NONE,
        TCP_CONNTRACK_SYN_SENT,
        TCP_CONNTRACK_SYN_RECV,
        TCP_CONNTRACK_ESTABLISHED,
        TCP_CONNTRACK_FIN_WAIT,
        TCP_CONNTRACK_CLOSE_WAIT,
        TCP_CONNTRACK_LAST_ACK,
        TCP_CONNTRACK_TIME_WAIT,
        TCP_CONNTRACK_CLOSE,
        TCP_CONNTRACK_LISTEN,
        TCP_CONNTRACK_MAX,
        TCP_CONNTRACK_IGNORE
};

/* Window scaling is advertised by the sender */
#define IP_CT_TCP_FLAG_WINDOW_SCALE             0x01

/* SACK is permitted by the sender */
#define IP_CT_TCP_FLAG_SACK_PERM                0x02

/* This sender sent FIN first */
#define IP_CT_TCP_FLAG_CLOSE_INIT               0x04

/* Be liberal in window checking */
#define IP_CT_TCP_FLAG_BE_LIBERAL               0x08

/* Has unacknowledged data */
#define IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED      0x10

struct nf_ct_tcp_flags {
        u_int8_t flags;
        u_int8_t mask;
};

#ifdef __KERNEL__

struct ip_ct_tcp_state {
        u_int32_t       td_end;         /* max of seq + len */
        u_int32_t       td_maxend;      /* max of ack + max(win, 1) */
        u_int32_t       td_maxwin;      /* max(win) */
        u_int8_t        td_scale;       /* window scale factor */
        u_int8_t        flags;          /* per direction options */
};

struct ip_ct_tcp
{
        struct ip_ct_tcp_state seen[2]; /* connection parameters per direction */
        u_int8_t        state;          /* state of the connection (enum tcp_conntrack) */
        /* For detecting stale connections */
        u_int8_t        last_dir;       /* Direction of the last packet (enum ip_conntrack_dir) */
        u_int8_t        retrans;        /* Number of retransmitted packets */
        u_int8_t        last_index;     /* Index of the last packet */
        u_int32_t       last_seq;       /* Last sequence number seen in dir */
        u_int32_t       last_ack;       /* Last sequence number seen in opposite dir */
        u_int32_t       last_end;       /* Last seq + len */
        u_int16_t       last_win;       /* Last window advertisement seen in dir */
};

#endif /* __KERNEL__ */

#endif /* _NF_CONNTRACK_TCP_H */