cppptools.cpp

PPP协议的实现演示

#include "globals.h"

/***************************************************************************
                          cppptools.cpp  -  description
                             -------------------
    begin                : Thu Jul 26 2001
    copyright            : (C) 2001 by stephane (birdy57)
    email                : [e-mail]
 ***************************************************************************/ 
    
/***************************************************************************
 *                                                                         *
 *   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 "cppptools.h"
    
unsigned short
 CPppTools::fcstab[256] = { 
0x0000,
    0x1189,
    0x2312,
    0x329b,
    0x4624,
    0x57ad,
    0x6536,
    0x74bf, 
0x8c48,
    0x9dc1,
    0xaf5a,
    0xbed3,
    0xca6c,
    0xdbe5,
    0xe97e,
    0xf8f7, 
0x1081,
    0x0108,
    0x3393,
    0x221a,
    0x56a5,
    0x472c,
    0x75b7,
    0x643e, 
0x9cc9,
    0x8d40,
    0xbfdb,
    0xae52,
    0xdaed,
    0xcb64,
    0xf9ff,
    0xe876, 
0x2102,
    0x308b,
    0x0210,
    0x1399,
    0x6726,
    0x76af,
    0x4434,
    0x55bd, 
0xad4a,
    0xbcc3,
    0x8e58,
    0x9fd1,
    0xeb6e,
    0xfae7,
    0xc87c,
    0xd9f5, 
0x3183,
    0x200a,
    0x1291,
    0x0318,
    0x77a7,
    0x662e,
    0x54b5,
    0x453c, 
0xbdcb,
    0xac42,
    0x9ed9,
    0x8f50,
    0xfbef,
    0xea66,
    0xd8fd,
    0xc974, 
0x4204,
    0x538d,
    0x6116,
    0x709f,
    0x0420,
    0x15a9,
    0x2732,
    0x36bb, 
0xce4c,
    0xdfc5,
    0xed5e,
    0xfcd7,
    0x8868,
    0x99e1,
    0xab7a,
    0xbaf3, 
0x5285,
    0x430c,
    0x7197,
    0x601e,
    0x14a1,
    0x0528,
    0x37b3,
    0x263a, 
0xdecd,
    0xcf44,
    0xfddf,
    0xec56,
    0x98e9,
    0x8960,
    0xbbfb,
    0xaa72, 
0x6306,
    0x728f,
    0x4014,
    0x519d,
    0x2522,
    0x34ab,
    0x0630,
    0x17b9, 
0xef4e,
    0xfec7,
    0xcc5c,
    0xddd5,
    0xa96a,
    0xb8e3,
    0x8a78,
    0x9bf1, 
0x7387,
    0x620e,
    0x5095,
    0x411c,
    0x35a3,
    0x242a,
    0x16b1,
    0x0738, 
0xffcf,
    0xee46,
    0xdcdd,
    0xcd54,
    0xb9eb,
    0xa862,
    0x9af9,
    0x8b70, 
0x8408,
    0x9581,
    0xa71a,
    0xb693,
    0xc22c,
    0xd3a5,
    0xe13e,
    0xf0b7, 
0x0840,
    0x19c9,
    0x2b52,
    0x3adb,
    0x4e64,
    0x5fed,
    0x6d76,
    0x7cff, 
0x9489,
    0x8500,
    0xb79b,
    0xa612,
    0xd2ad,
    0xc324,
    0xf1bf,
    0xe036, 
0x18c1,
    0x0948,
    0x3bd3,
    0x2a5a,
    0x5ee5,
    0x4f6c,
    0x7df7,
    0x6c7e, 
0xa50a,
    0xb483,
    0x8618,
    0x9791,
    0xe32e,
    0xf2a7,
    0xc03c,
    0xd1b5, 
0x2942,
    0x38cb,
    0x0a50,
    0x1bd9,
    0x6f66,
    0x7eef,
    0x4c74,
    0x5dfd, 
0xb58b,
    0xa402,
    0x9699,
    0x8710,
    0xf3af,
    0xe226,
    0xd0bd,
    0xc134, 
0x39c3,
    0x284a,
    0x1ad1,
    0x0b58,
    0x7fe7,
    0x6e6e,
    0x5cf5,
    0x4d7c, 
0xc60c,
    0xd785,
    0xe51e,
    0xf497,
    0x8028,
    0x91a1,
    0xa33a,
    0xb2b3, 
0x4a44,
    0x5bcd,
    0x6956,
    0x78df,
    0x0c60,
    0x1de9,
    0x2f72,
    0x3efb, 
0xd68d,
    0xc704,
    0xf59f,
    0xe416,
    0x90a9,
    0x8120,
    0xb3bb,
    0xa232, 
0x5ac5,
    0x4b4c,
    0x79d7,
    0x685e,
    0x1ce1,
    0x0d68,
    0x3ff3,
    0x2e7a, 
0xe70e,
    0xf687,
    0xc41c,
    0xd595,
    0xa12a,
    0xb0a3,
    0x8238,
    0x93b1, 
0x6b46,
    0x7acf,
    0x4854,
    0x59dd,
    0x2d62,
    0x3ceb,
    0x0e70,
    0x1ff9, 
0xf78f,
    0xe606,
    0xd49d,
    0xc514,
    0xb1ab,
    0xa022,
    0x92b9,
    0x8330, 
0x7bc7,
    0x6a4e,
    0x58d5,
    0x495c,
    0x3de3,
    0x2c6a,
    0x1ef1,
    0x0f78 
};


CPppTools::CPppTools() 
{



}


CPppTools::~CPppTools()
{

}


/** calcul le checksum tcp */ 
unsigned int CPppTools::pppfchks(unsigned int fcs, Byte * cp, int len) 
{
    
int k;
    
for (k = 0; k < len; k++)
	
fcs = PPP_FCS(fcs, cp[k]);
    
fcs &= 0xFFFF;
    
return fcs;

}


/** recalcul le checksum ppp */ 
void CPppTools::Recompute_pppfchks(Byte * Buffer, int Longueur) 
{
    
Word crc;
    

crc = pppfchks(PPP_INITFCS, Buffer, Longueur - 2);
    
crc = ~crc;
    
Buffer[Longueur - 1] = ((crc >> 8) & 0xff);
    
Buffer[Longueur - 2] = (crc & 0xff);

}


/** decode une chaine coder LCP */ 

int CPppTools::Decode_Lcp(Byte * buffer, int Longueur) 
{
    
int ESC_Actif = 0;
    
int i;
    
int pos = 0;
    
Byte c;
    

for (i = 0; i < Longueur; i++) {
	
c = buffer[i];
	
if (c == 0x7d) {
	    ESC_Actif = 1;
	    continue;
	}
	
if (ESC_Actif)
	    c = c ^ 0x20;
	
ESC_Actif = 0;
	
buffer[pos] = c;
	
pos++;
    
}
    
return pos;

}


/** encode une chaine en LCP */ 
int CPppTools::Encode_Lcp(Byte * buffer, int Longueur) 
{
    
int i;
    
int pos = 0;
    
Byte c;
    
Byte tmp[3000];
    

for (i = 0; i < Longueur; i++) {
	
c = buffer[i];
	
	    /* SI la valeur est comprise entre 0 - 20 xor avec 20 preced