学步园

#include <fstream>
#include <iostream>
#include <iomanip>           //I/O流控制头文件
#include <WINSOCK2.H>
using namespace std;
struct eth_header            //帧头
{
unsigned char eth_dst[6];
unsigned char eth_src[6];
unsigned short upper_pro; //上层协议    0800表示是ip数据包
}; 
struct ip_header              //ip报头
{
union
{
unsigned char version;  //版本
unsigned char ihl;      //报头长度
};
unsigned char tos;          //服务类型
unsigned short total_len;   //总长度 
unsigned short identifer;   //标识
union
{
unsigned short flags;    //标志
unsigned short offset;   //片偏移
};
unsigned char TTL;           //生存周期
unsigned char protocol;      //协议
unsigned short checksum;     //头部校验和
unsigned char ip_src[4];     //源ip地址
unsigned char ip_dst[4];     //目的ip地址
unsigned int option;         //选项+填充
//数据
};

  void main()
  {
  int temp[38];               //? why 38?
  ifstream infile("D:\\data"); //打开文件
  int i;
  for (i=0;i<38;i++)
  {
		infile>>hex>>temp[i];    //hex 格式化为十六进制数值数据 输入和输出
		}
		
		  infile.close();
		  struct eth_header eth;
		  struct ip_header ip;
		  
			for (i=0;i<6;i++)
			{
			eth.eth_dst[i]=(unsigned char)temp[i];
			}
			for (i=6;i<12;i++)
			{
			eth.eth_src[i-6]=(unsigned char)temp[i];
			}
			eth.upper_pro = (temp[12]<<8)|temp[13];         //? why 左移8位
			//以下给ip头部变量赋值
			ip.version = (unsigned char)temp[14];
			ip.tos = (unsigned char)temp[15];
			ip.total_len=(temp[16]<<8)|temp[17];
			ip.identifer = (temp[18]<<8)|temp[19];
			ip.flags = (unsigned short)(temp[20]<<8)|(temp[21]);
			ip.TTL = (unsigned char)temp[22];
			ip.protocol = (unsigned char)temp[23];
			ip.checksum = (temp[24]<<8)|temp[25];
			for (i=26;i<30;i++)
			{
			ip.ip_src[i-26]=(unsigned char)temp[i];
			}
			for (i=30;i<34;i++)
			{
			ip.ip_dst[i-30]=(unsigned char)temp[i];
			}
			//以下输出mac头部信息
			cout<<"输出mac帧头部信息（十六进制）:"<<endl;
			cout<<"目的mac地址为:";
			for (i=0;i<5;i++)
			{   
			//setfill是设置填充字符，setw设置输出的宽度，它们的作用表现在紧接着输入的字符串上
			cout<<setfill('0')<<setw(2)<<hex<<(int)eth.eth_dst[i]<<"-";//空的地方填充0,宽度为2
			}
			cout<<setfill('0')<<setw(2)<<hex<<(int)eth.eth_dst[5]<<endl;
			cout<<"源mac地址为:";
			for (i=0;i<5;i++)
			{
			cout<<setfill('0')<<setw(2)<<hex<<(int)eth.eth_src[i]<<"-";
			}
			cout<<setfill('0')<<setw(2)<<hex<<(int)eth.eth_src[5]<<endl;
			
			  cout<<"上层协议类型为:";
			  cout<<setfill('0')<<setw(4)<<hex<<eth.upper_pro<<endl;
			  cout<<"-----------------------------"<<endl;
			  //以下输出ip头部信息
			  cout<<"输出ip头部信息（十进制）:"<<endl;
			  cout<<"版本:"<<dec<<(ip.version>>4)<<endl;    //dec十进制 oct八进制 hex十六进制
			  ip.ihl=ip.version&0x0f;
			  cout<<"ip头部长度（ihl）:"<<(ip.ihl*4)<<endl;
			  cout<<"服务类型:"<<(int)ip.tos<<"("<<"优先权子字段"
			  <<(ip.tos>>5)<<"tos子字段:"<<((ip.tos>>1)&0x0f)<<")"<<endl;
			  cout<<"总长度:"<<(int)ip.total_len<<endl;
			  cout<<"标识符:"<<(int)ip.identifer<<endl;
			  cout<<"片偏移:"<<(ip.offset&0x1fff)<<endl;
			  cout<<"生存期:"<<(int)ip.TTL<<endl;
			  cout<<"协议:"<<(int)ip.protocol<<endl;
			  cout<<"首部检校和:"<<(int)ip.checksum<<endl;
			  cout<<"源ip地址:";
			  for(i=0;i<3;i++)
			  {
			  cout<<(int)ip.ip_src[i]<<".";
			  }
			  cout<<(int)ip.ip_src[3]<<endl;
			  cout<<"目的ip地址:";
			  for (i=0;i<3;i++)
			  {
			  cout<<(int)ip.ip_dst[i]<<".";
			  }
			  cout<<(int)ip.ip_dst[3]<<endl;
			  
				//以下验证有没有选项字段
				if (ip.ihl==5)
				{
				cout<<"没有选项字段"<<endl;
				for (i=34;i<38;i++)
				{
				temp[i]=0;
				}
				}
				else
				{
				ip.option=(unsigned int)(temp[34]<<24)|(temp[35]<<16)|(temp[36]<<8)|temp[37];
				cout<<"选项:"<<(int)ip.option<<endl;//如果有选项字段 将选项和填充一起输出
				}
				cout<<"-----------------------------"<<endl;
				
				  //以下验证ip数据包头部的正确性
				  unsigned short m1,m2,sum;
				  unsigned int sum1=0;
				  for (i=14;i<38;i=i+2)
				  {
				  m1 = (unsigned short)(temp[i]<<8);
				  m2 = (unsigned short)temp[i+1];
				  sum = m1|m2;
				  sum1+=sum;
				  }
				  sum1 = (sum1>>16)+(sum1&0xffff);   //oxffff截掉进位那一位
				  sum1 = (sum1>>16)+(sum1&0xffff);
				  sum1 = (unsigned short)~sum1;
				  if (sum1==0)
				  {
				  cout<<"ip数据包是正确的"<<endl;
				  }
				  else
				  {
				  cout<<"ip数据包是错误的"<<endl;
				  }
				  cout<<"-----------------------------"<<endl;
				  cin.get();
				  
					}