vjhc.h

用于嵌入式系统的TCP/IP协议栈

/***********************************************************************/
/*                                                                     */
/*   Module:  tcp_ip/ppp/vjhc.h                                        */
/*   Release: 2001.3                                                   */
/*   Version: 2001.0                                                   */
/*   Purpose: Include file for Van Jacobson header compression         */
/*                                                                     */
/*---------------------------------------------------------------------*/
/*                                                                     */
/*               Copyright 2001, Blunk Microsystems                    */
/*                      ALL RIGHTS RESERVED                            */
/*                                                                     */
/*   Licensees have the non-exclusive right to use, modify, or extract */
/*   this computer program for software development at a single site.  */
/*   This program may be resold or disseminated in executable format   */
/*   only. The source code may not be redistributed or resold.         */
/*                                                                     */
/*---------------------------------------------------------------------*/
/*                                                                     */
/*   Copyright (c) 1989 Regents of the University of California.       */
/*   All rights reserved.                                              */
/*                                                                     */
/*   Redistribution and use in source and binary forms are permitted   */
/*   provided that the above copyright notice and this paragraph are   */
/*   duplicated in all such forms and that any documentation,          */
/*   advertising materials, and other materials related to such        */
/*   distribution and use acknowledge that the software was developed  */
/*   by the University of California, Berkeley.  The name of the       */
/*   University may not be used to endorse or promote products derived */
/*   from this software without specific prior written permission.     */
/*                                                                     */
/*   THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR    */
/*   IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED    */
/*   WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR        */
/*   PURPOSE.                                                          */
/*                                                                     */
/***********************************************************************/
#ifndef _VJHC_H
#define _VJHC_H

#include "../ip/ip.h"
#include "../tcp/tcp.h"

/***********************************************************************/
/* Configuration                                                       */
/***********************************************************************/
#define VJ_SLOT_HI      16  /* maximum # of slots */
#define VJ_SLOT_DEF     16  /* default # of slots */
#define VJ_SLOT_LO      2   /* minimum # of slots */

#if (VJ_SLOT_DEF < 2) || (VJ_SLOT_HI < 2) || (VJ_SLOT_LO < 2) || \
    (VJ_SLOT_DEF > 256) || (VJ_SLOT_HI > 256) || (VJ_SLOT_LO > 256)
#error Slots must be in range 2 to 256
#endif

/***********************************************************************/
/* Symbol Definitions                                                  */
/***********************************************************************/
#define MAX_HDR 128     /* max TCP+IP hdr length (by protocol def) */

/***********************************************************************/
/* Type Definitions                                                    */
/***********************************************************************/
/*
** "state" data for each active TCP conversation on the wire.  This is
** basically a copy of the entire IP/TCP header from the last packet
** together with a small identifier the transmit & receive ends of the
** line use to locate saved header.
*/
struct cstate
{
  struct cstate *cs_next; /* next MRU cstate (xmit only) */
  ui16 cs_hlen;         /* size of hdr (receive only) */
  ui8  cs_id;           /* connection # associated with this state */
  ui8  cs_filler;
  union
  {
    char hdr[MAX_HDR];
    Ip csu_ip;          /* IP/TCP hdr from most recent packet */
  } vjcs_u;
};
#define cs_ip vjcs_u.csu_ip
#define cs_hdr vjcs_u.csu_hdr

/*
** All the state data for one serial line (need one of these per line).
*/
struct vjcompress
{
  struct cstate *last_cs;       /* most recently used tstate */
  ui8 last_recv;                /* last rcvd conn. id */
  ui8 last_xmit;                /* last sent conn. id */
  ui8 tslot_limit;              /* highest transmit slot id (0-l) */
  ui8 rslot_limit;              /* highest receive slot id (0-l) */
  ui16 flags;
  struct cstate tstate[VJ_SLOT_HI]; /* xmit connection states */
  struct cstate rstate[VJ_SLOT_HI]; /* receive connection states */
};

/***********************************************************************/
/* Function Prototypes                                                 */
/***********************************************************************/
void vjhc_init(struct vjcompress *comp, int rslots, int tslots);
uint vjhc_compress(NetBuf *buf, struct vjcompress *comp, int comp_cid);
int  vjhc_uncompress(struct vjcompress *comp, NetBuf *buf);
int  vjhc_remember(struct vjcompress *comp, const NetBuf *buf);
void vjhc_toss(struct vjcompress *comp);

#endif  /* _VJHC_H */