cvjcompress.cpp

PPP协议的实现演示

/***************************************************************************
                          cvjcompress.h  -  description
                             -------------------
    begin                : Wed Jun 6 2001
    copyright            : (C) 2001 by stephane (birdy57)  &  Nicolas Jouanne
    email                : [e-mail]
 ***************************************************************************/

// Fichier original birdy57 + vjcompess de la rfc 1144

// Modifier par Nicolas Jouanne pour une meilleur implementation au C++
// (restructuration des source de la rfc1144 du c vers le C++)
// et deboguage de l'enssemble !!

/***************************************************************************
 *                                                                         *
 *   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     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include "cvjcompress.h"

#define mtod(m, t) ((t)(m->m_off))


CVjcompress::CVjcompress()
{
    vjstruct = (struct slcompress *) new char[10500];
    m_cTcpIpHeader = new CTcpIpHeader;

    // testvjcompress
    sl_compress_init(vjstruct);
}

CVjcompress::~CVjcompress()
{
}


/** Decompresse une trame */
unsigned short
 CVjcompress::Deflate(char *sBuffer, int nLen)
{
    unsigned int nType;
    char ssTmpBuffer[2000];
    char *sTmpBuffer = &ssTmpBuffer[0];
    char *pResult;
    unsigned short nRet = nLen;


// trame non compresse
    if (sBuffer[0] != 0x45) {

	if (sBuffer[0] != 0x75)
	    nType = TYPE_COMPRESSED_TCP;
	else {
	    nType = TYPE_UNCOMPRESSED_TCP;
	    sBuffer[0] = 0x45;
	}

	memcpy((sTmpBuffer + 200), sBuffer, nLen);

	// demande de decompression
	pResult =
	    (char *) sl_uncompress_tcp((u_char *) (sTmpBuffer + 200), nLen,
				       nType, vjstruct);

	// trame non compresser ou erreur
	if (pResult != NULL) {
	    nRet += ((sTmpBuffer + 200) - pResult);
	    memcpy(sBuffer, pResult, nRet);
	}
    }
    return nRet;
}

/** Compress une trame TCP/IP */
int CVjcompress::Compress(char *sBuffer, int nLon)
{
    int nType, nRet;
    mbuf mBuf;


    nLon = TcpNormal(sBuffer, nLon);
    nRet = nLon;

// la compression
    mBuf.m_off = (unsigned char *) sBuffer;
    mBuf.m_len = nLon;

    nType = sl_compress_tcp(&mBuf, vjstruct, 1);

    if ((nType != TYPE_IP) && (nType != TYPE_ERROR)) {
	nRet = mBuf.m_len;
	// Type non compresser ? 0x75 sinon +0x80
	(nType == TYPE_UNCOMPRESSED_TCP) ? (sBuffer[0] = 0x75) :	/* ici c du compresser */
	    (sBuffer[0] += 0x80);
    }

    return nRet;
}

/** Reduit l'entete