usr/src/sys/netinet/tcp.h

/* tcp.h 1.13 81/11/04 */

/*
 * Tcp header.  Fits over the ip header after option removed.
 *
 * SHOULD MAKE A CLEAN HEADER FOR USE BY USERS.
 */
struct th {
        struct  th *t_next;             /* -> next tcp on rcv chain */
        struct  th *t_prev;             /* -> prev tcp on rcv chain */
        u_char  t_x1;                   /* (unused) */
        u_char  t_pr;                   /* protocol */
/* by rights, t_len should be a u_short, but this makes operations */
/* on it very dangerous as comparisons become unsigned and comparing */
/* against negative numbers then fails... we don't expect any > 32767 */
/* byte segments, so pragmatically delcare it to be a short */
        short   t_len;                  /* seg length */
        struct  socket t_s;             /* source internet address */
        struct  socket t_d;             /* destination internet address */
        u_short t_src;                  /* source port */
        u_short t_dst;                  /* destination port */
        seq_t   t_seq;                  /* sequence number */
        seq_t   t_ackno;                /* acknowledgement number */
#define t_end(x) (x->t_seq + x->t_len - 1)
        u_char
                t_x2:4,                 /* (unused) */
                t_off:4;                /* data offset */
        u_char  th_flags;
#define TH_FIN  001
#define TH_SYN  002
#define TH_RST  004
#define TH_EOL  010
#define TH_ACK  020
#define TH_URG  040
        u_short t_win;                  /* window */
        u_short t_sum;                  /* checksum */
        u_short t_urp;                  /* urgent pointer */
};

/*
 * Tcp control block.
 */
struct tcb {
/* first four elements of this struct must match tcphead below */
        struct  th *t_rcv_next;         /* first el on rcv queue */
        struct  th *t_rcv_prev;         /* last el on rcv queue */
        struct  tcb *tcb_next;          /* next tcb */
        struct  tcb *tcb_prev;          /* next tcb */
/* end must match */
        struct  th *t_template;         /* skeletal packet for transmit */
        struct  ucb *t_ucb;             /* ucb */
        struct  mbuf *t_rcv_unack;      /* unacked message queue */
        short   seqcnt;
        short   xxx;
        seq_t   iss;                    /* initial send seq # */
        seq_t   irs;                    /* initial recv seq # */
        seq_t   rcv_urp;                /* rcv urgent pointer */
        seq_t   rcv_nxt;                /* next seq # to rcv */
        seq_t   rcv_end;                /* rcv eol pointer */
        seq_t   snd_off;                /* seq # of first datum in send buf */
        seq_t   seq_fin;                /* seq # of FIN sent */
        seq_t   snd_end;                /* send eol pointer */
        seq_t   snd_urp;                /* snd urgent pointer */
        seq_t   snd_lst;                /* seq # of last sent datum */
        seq_t   snd_nxt;                /* seq # of next datum to send */
        seq_t   snd_una;                /* seq # of first unacked datum */
        seq_t   snd_wl;                 /* seq # of last sent window */
        seq_t   snd_hi;                 /* highest seq # sent */
        seq_t   snd_wnd;                /* send window max */
        seq_t   t_rexmt_val;            /* val saved in rexmt timer */
        seq_t   t_rtl_val;              /* val saved in rexmt too long timer */
        seq_t   t_xmt_val;              /* seq # sent when xmt timer started */

        /* various flags and state variables */

        u_short tc_flags;
#define TC_ACK_DUE      0x0001          /* must we send ACK */
#define TC_CANCELLED    0x0002          /* retransmit timer cancelled */
#define TC_DROPPED_TXT  0x0004          /* dropped incoming data */
#define TC_FIN_RCVD     0x0008          /* FIN received */
#define TC_FORCE_ONE    0x0010          /* force sending of one byte */
#define TC_NEW_WINDOW   0x0020          /* received new window size */
#define TC_REXMT        0x0040          /* this msg is a retransmission */
#define TC_SND_FIN      0x0080          /* FIN should be sent */
#define TC_SND_RST      0x0100          /* RST should be sent */
#define TC_SND_URG      0x0200          /* urgent data to send */
#define TC_SYN_ACKED    0x0400          /* SYN has been ACKed */
#define TC_SYN_RCVD     0x0800          /* SYN has been received */
#define TC_USR_CLOSED   0x1000          /* user has closed connection */
#define TC_WAITED_2_ML  0x2000          /* wait time for FIN ACK is up */
#define TC_NET_KEEP     0x4000          /* don't free this net input */
#define TC_USR_ABORT    0x8000          /* user has closed and does not expect
                                           to receive any more data */

        u_short t_lport;                /* local port */
        u_short t_fport;                /* foreign port */
        u_char  t_state;                /* state of this connection */
        u_char  t_xmtime;               /* current rexmt time */

        /* timers */

        u_char  t_init;                 /* initialization too long */
        u_char  t_rexmt;                /* retransmission */
        u_char  t_rexmttl;              /* retransmit too long */
        u_char  t_persist;              /* retransmit persistance */
        u_char  t_finack;               /* fin acknowledged */
        u_char  t_xmt;                  /* round trip transmission time */

        seq_t   rcv_adv;                /* advertised window */
};
struct tcbhead {
        struct  th *t_rcv_next,*t_rcv_prev;
        struct  tcb *tcb_next,*tcb_prev;
};

/*
 * TCP timers.
 */
#define TINIT           0
#define TREXMT          1
#define TREXMTTL        2
#define TPERSIST        3
#define TFINACK         4
#define TNTIMERS        5

/*
 * Tcp machine predicates
 */
#define ack_ok(x, y) \
    (((y)->th_flags&TH_ACK)==0 || \
      ((x)->iss < (y)->t_ackno && (y)->t_ackno <= (x)->snd_hi))

#define syn_ok(x, y) \
    ((y)->th_flags&TH_SYN)

#define ack_fin(x, y) \
    ((x)->seq_fin > (x)->iss && (y)->t_ackno > (x)->seq_fin)

#define rcv_empty(x) \
    (((x)->tc_flags&TC_USR_ABORT) || \
      ((x)->t_ucb->uc_rbuf == NULL && (x)->t_rcv_next == (x)->t_rcv_prev))

#define ISSINCR         128             /* increment for iss each second */
#define TCPSIZE         20              /* size of TCP leader (bytes) */

/*
 * THESE NEED TO BE JUSTIFIED!
 */
#define T_2ML           10              /* 2*maximum packet lifetime */
#define T_PERS          5               /* persist time */
#define T_INIT          30              /* init too long timeout */
#define T_REXMT         1               /* base for retransmission time */
#define T_REXMTTL       30              /* retransmit too long timeout */
#define T_REMAX         30              /* maximum retransmission time */

#define ACTIVE          1               /* active open */
#define PASSIVE         0               /* passive open */

#ifdef TCPDEBUG
#define TDBSIZE         50
/*
 * Tcp debugging record.
 */
struct tcp_debug {
        long    td_tod;                 /* time of day */
        struct  tcb *td_tcb;            /* -> tcb */
        char    td_old;                 /* old state */
        char    td_inp;                 /* input */
        char    td_tim;                 /* timer id */
        char    td_new;                 /* new state */
        seq_t   td_sno;                 /* seq_t number */
        seq_t   td_ano;                 /* acknowledgement */
        u_short td_wno;                 /* window */
        u_short td_lno;                 /* length */
        u_char  td_flg;                 /* message flags */
};
#endif

#ifdef KERNEL
struct  tcbhead tcb;                    /* tcp tcb list head */
seq_t   tcp_iss;                        /* tcp initial send seq # */
int     tcpconsdebug;                   /* set to 1 traces on console */
#ifdef TCPDEBUG
struct  tcp_debug tcp_debug[TDBSIZE];
#endif
int     tdbx;                   /* rotating index into tcp_debug */
struct  th *tcp_template();
#endif

#define SEQ_LT(a,b)     ((int)((a)-(b)) < 0)
#define SEQ_LEQ(a,b)    ((int)((a)-(b)) <= 0)
#define SEQ_GT(a,b)     ((int)((a)-(b)) > 0)
#define SEQ_GEQ(a,b)    ((int)((a)-(b)) >= 0)
struct  th *tcp_template();