1. 根目录:
2. include
3. net
4. dn_nsp.h

#ifndef _NET_DN_NSP_H
#define _NET_DN_NSP_H
/******************************************************************************
    (c) 1995-1998 E.M. Serrat		emserrat@geocities.com
    
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
*******************************************************************************/
/* dn_nsp.c functions prototyping */

void dn_nsp_send_data_ack(struct sock *sk);
void dn_nsp_send_oth_ack(struct sock *sk);
void dn_nsp_delayed_ack(struct sock *sk);
void dn_send_conn_ack(struct sock *sk);
void dn_send_conn_conf(struct sock *sk, gfp_t gfp);
void dn_nsp_send_disc(struct sock *sk, unsigned char type,
		      unsigned short reason, gfp_t gfp);
void dn_nsp_return_disc(struct sk_buff *skb, unsigned char type,
			unsigned short reason);
void dn_nsp_send_link(struct sock *sk, unsigned char lsflags, char fcval);
void dn_nsp_send_conninit(struct sock *sk, unsigned char flags);

void dn_nsp_output(struct sock *sk);
int dn_nsp_check_xmit_queue(struct sock *sk, struct sk_buff *skb,
			    struct sk_buff_head *q, unsigned short acknum);
void dn_nsp_queue_xmit(struct sock *sk, struct sk_buff *skb, gfp_t gfp,
		       int oob);
unsigned long dn_nsp_persist(struct sock *sk);
int dn_nsp_xmit_timeout(struct sock *sk);

int dn_nsp_rx(struct sk_buff *);
int dn_nsp_backlog_rcv(struct sock *sk, struct sk_buff *skb);

struct sk_buff *dn_alloc_skb(struct sock *sk, int size, gfp_t pri);
struct sk_buff *dn_alloc_send_skb(struct sock *sk, size_t *size, int noblock,
				  long timeo, int *err);

#define NSP_REASON_OK 0		/* No error */
#define NSP_REASON_NR 1		/* No resources */
#define NSP_REASON_UN 2		/* Unrecognised node name */
#define NSP_REASON_SD 3		/* Node shutting down */
#define NSP_REASON_ID 4		/* Invalid destination end user */
#define NSP_REASON_ER 5		/* End user lacks resources */
#define NSP_REASON_OB 6		/* Object too busy */
#define NSP_REASON_US 7		/* Unspecified error */
#define NSP_REASON_TP 8		/* Third-Party abort */
#define NSP_REASON_EA 9		/* End user has aborted the link */
#define NSP_REASON_IF 10	/* Invalid node name format */
#define NSP_REASON_LS 11	/* Local node shutdown */
#define NSP_REASON_LL 32	/* Node lacks logical-link resources */
#define NSP_REASON_LE 33	/* End user lacks logical-link resources */
#define NSP_REASON_UR 34	/* Unacceptable RQSTRID or PASSWORD field */
#define NSP_REASON_UA 36	/* Unacceptable ACCOUNT field */
#define NSP_REASON_TM 38	/* End user timed out logical link */
#define NSP_REASON_NU 39	/* Node unreachable */
#define NSP_REASON_NL 41	/* No-link message */
#define NSP_REASON_DC 42	/* Disconnect confirm */
#define NSP_REASON_IO 43	/* Image data field overflow */

#define NSP_DISCINIT 0x38
#define NSP_DISCCONF 0x48

/*------------------------- NSP - messages ------------------------------*/
/* Data Messages */
/*---------------*/

/* Data Messages    (data segment/interrupt/link service)               */

struct nsp_data_seg_msg {
	__u8   msgflg;
	__le16 dstaddr;
	__le16 srcaddr;
} __packed;

struct nsp_data_opt_msg {
	__le16 acknum;
	__le16 segnum;
	__le16 lsflgs;
} __packed;

struct nsp_data_opt_msg1 {
	__le16 acknum;
	__le16 segnum;
} __packed;


/* Acknowledgment Message (data/other data)                             */
struct nsp_data_ack_msg {
	__u8   msgflg;
	__le16 dstaddr;
	__le16 srcaddr;
	__le16 acknum;
} __packed;

/* Connect Acknowledgment Message */
struct  nsp_conn_ack_msg {
	__u8 msgflg;
	__le16 dstaddr;
} __packed;


/* Connect Initiate/Retransmit Initiate/Connect Confirm */
struct  nsp_conn_init_msg {
	__u8   msgflg;
#define NSP_CI      0x18            /* Connect Initiate     */
#define NSP_RCI     0x68            /* Retrans. Conn Init   */
	__le16 dstaddr;
	__le16 srcaddr;
	__u8   services;
#define NSP_FC_NONE   0x00            /* Flow Control None    */
#define NSP_FC_SRC    0x04            /* Seg Req. Count       */
#define NSP_FC_SCMC   0x08            /* Sess. Control Mess   */
#define NSP_FC_MASK   0x0c            /* FC type mask         */
	__u8   info;
	__le16 segsize;
} __packed;

/* Disconnect Initiate/Disconnect Confirm */
struct  nsp_disconn_init_msg {
	__u8   msgflg;
	__le16 dstaddr;
	__le16 srcaddr;
	__le16 reason;
} __packed;



struct  srcobj_fmt {
	__u8   format;
	__u8   task;
	__le16 grpcode;
	__le16 usrcode;
	__u8   dlen;
} __packed;

/*
 * A collection of functions for manipulating the sequence
 * numbers used in NSP. Similar in operation to the functions
 * of the same name in TCP.
 */
static __inline__ int dn_before(__u16 seq1, __u16 seq2)
{
        seq1 &= 0x0fff;
        seq2 &= 0x0fff;

        return (int)((seq1 - seq2) & 0x0fff) > 2048;
}


static __inline__ int dn_after(__u16 seq1, __u16 seq2)
{
        seq1 &= 0x0fff;
        seq2 &= 0x0fff;

        return (int)((seq2 - seq1) & 0x0fff) > 2048;
}

static __inline__ int dn_equal(__u16 seq1, __u16 seq2)
{
        return ((seq1 ^ seq2) & 0x0fff) == 0;
}

static __inline__ int dn_before_or_equal(__u16 seq1, __u16 seq2)
{
	return (dn_before(seq1, seq2) || dn_equal(seq1, seq2));
}

static __inline__ void seq_add(__u16 *seq, __u16 off)
{
        (*seq) += off;
        (*seq) &= 0x0fff;
}

static __inline__ int seq_next(__u16 seq1, __u16 seq2)
{
	return dn_equal(seq1 + 1, seq2);
}

/*
 * Can we delay the ack ?
 */
static __inline__ int sendack(__u16 seq)
{
        return (int)((seq & 0x1000) ? 0 : 1);
}

/*
 * Is socket congested ?
 */
static __inline__ int dn_congested(struct sock *sk)
{
        return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
}

#define DN_MAX_NSP_DATA_HEADER (11)

#endif /* _NET_DN_NSP_H */