Ping程序实现

待我称王封你为后i 2022-02-05 02:53 185阅读 0赞

OSI模型与ICP/IP模型对比：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0hCX1Byb2dyYW1tZXI_size_16_color_FFFFFF_t_70][]

Ping通过发送ICMP回显请求来确定过一个主机是否存在：

#include "stdafx.h"
    #include "Winsock2.h"
    #pragma comment ( lib, "ws2_32.lib" )
    
    #include <windows.h>
    #include "stdio.h"
    
    // 定义默认的缓冲区长度
    #define DEF_BUF_SIZE		1024
    // 定义IP包头长度
    #define IP_HEADER_SIZE		20
    // 定义ICMP包头长度
    #define ICMP_HEADER_SIZE	( sizeof(ICMP_HEADER) )
    // 定义ICMP包实体数据长度
    #define ICMP_DATA_SIZE		32
    // 定义ICMP包总长度
    #define ICMP_PACK_SIZE		( ICMP_HEADER_SIZE + ICMP_DATA_SIZE )
    // 定义ICMP包头
    typedef struct _ICMP_HEADER {
    	BYTE	bType ;			// 类型
    	BYTE	bCode ;			// 代码
    	USHORT	nCheckSum ;		// 校验和
    	USHORT	nId ;			// 标识，本进程ID
    	USHORT	nSequence ;		// 序列号
    	UINT	nTimeStamp ;	// 可选项，这里为时间，用于计算时间
    } ICMP_HEADER, *PICMP_HEADER ;
    
    // 用于格式化输出信息的缓冲区
    char szInfo[DEF_BUF_SIZE] ;
    
    BOOL Ping ( char* lpDestIp ) ;
    USHORT GetCheckSum ( LPBYTE lpBuf, DWORD dwSize ) ;
    
    int main(int argc, char* argv[])
    {
    	int value[4] ;
    	char szDestIp[DEF_BUF_SIZE] = {0} ;
    	while ( scanf ( "%s", szDestIp) )
    		Ping ( szDestIp ) ;
    	return 0;
    }
    
    // 实现PING程序
    // 参数：目标地址IP字符串，格式如“127.0.0.1”
    BOOL Ping ( char* lpDestIp )
    {
    	// 设置目标地址
    	SOCKADDR_IN DestSockAddr ;
    	DestSockAddr.sin_family = AF_INET ;
    	DestSockAddr.sin_addr.s_addr = inet_addr( lpDestIp ) ;
    	DestSockAddr.sin_port = htons ( 0 ) ;
    
    	// 创建ICMP回显请求包
    	char ICMPPack[ICMP_PACK_SIZE] = {0} ;
    	PICMP_HEADER pICMPHeader = (PICMP_HEADER)ICMPPack ;
    	pICMPHeader->bType = 8 ;
    	pICMPHeader->bCode = 0 ;
    	pICMPHeader->nId = (USHORT)::GetCurrentProcessId() ;
    	pICMPHeader->nCheckSum = 0 ;
    	pICMPHeader->nTimeStamp = 0 ;
    	memset ( &(ICMPPack[ICMP_HEADER_SIZE]), 'E', ICMP_DATA_SIZE ) ;	// 填充数据部分，内容任意
    
    	// 初始化WinSock库
    	WORD wVersionRequested = MAKEWORD( 2, 2 );
    	WSADATA wsaData;
    	if ( WSAStartup( wVersionRequested, &wsaData ) != 0 )
    		return FALSE ;
    
    	// 创建原始套接字
    	SOCKET	RawSock = socket ( AF_INET, SOCK_RAW, IPPROTO_ICMP ) ;
    	if ( RawSock == INVALID_SOCKET )
    	{
    		printf ( "Create socket error!\n" ) ;
    		return FALSE ;
    	}
    	
    	// 设置接收超时为1秒
    	int nTime = 1000 ;
    	int ret = ::setsockopt ( RawSock, SOL_SOCKET,SO_RCVTIMEO, (char*)&nTime, sizeof(nTime));
    	
    	char szRecvBuf [ DEF_BUF_SIZE] ;
    	SOCKADDR_IN	SourSockAddr ;
    	for ( int i = 0 ; i < 4; i++ )
    	{
    		pICMPHeader->nCheckSum = 0 ;				// 初始时校验值为0
    		pICMPHeader->nSequence = i ;				// 序号
    		pICMPHeader->nTimeStamp = ::GetTickCount() ;// 当前时间
    
    		// 计算校验值，校验值要在ICMP数据报创建完才能计算
    		pICMPHeader->nCheckSum = GetCheckSum ( (LPBYTE)ICMPPack, ICMP_PACK_SIZE ) ;
    		
    		// 发送ICMP数据包
    		int nRet = ::sendto ( RawSock, ICMPPack, ICMP_PACK_SIZE,0,(SOCKADDR*)&DestSockAddr, sizeof(DestSockAddr) ) ;
    		if ( nRet == SOCKET_ERROR )
    		{
    			printf ( "sendto error!\n" ) ;
    			return FALSE ;
    		}
    
    		// 接收ICMP响应
    		int nLen = sizeof(SourSockAddr) ;
    		nRet = ::recvfrom ( RawSock, szRecvBuf, DEF_BUF_SIZE,0,(SOCKADDR*)&SourSockAddr, &nLen ) ;
    		if ( nRet == SOCKET_ERROR )
    		{
    			if ( ::WSAGetLastError() == WSAETIMEDOUT )
    			{
    				printf ( "Request Timeout\n" ) ;
    				continue ;
    			}
    			else
    			{
    				printf ( "recvfrom error!\n" ) ;
    				return FALSE ;
    			}
    		}
    
    		// 计算ICMP数据报的时间差
    		int nTime = ::GetTickCount() - pICMPHeader->nTimeStamp ;
    
    		int nRealSize = nRet - IP_HEADER_SIZE - ICMP_HEADER_SIZE ;
    		if ( nRealSize < 0  )
    		{
    			printf ( "To less recv bytes!\n" ) ;
    			continue ;
    		}
    
    		// 检测是否当前所发出的ICMP响应包
    		PICMP_HEADER pRecvHeader = (PICMP_HEADER)(szRecvBuf+IP_HEADER_SIZE) ;
    		if ( pRecvHeader->bType != 0 )
    		{
    			printf ( "Not ICMP respond type!\n" ) ;
    			return FALSE ;
    		}
    
    		if ( pRecvHeader->nId != ::GetCurrentProcessId () )
    		{
    			printf ( "not valid id!\n" ) ;
    			return FALSE ;
    		}
    
    		printf ( "%d bytes replay from %s : bytes=%d time=%dms\n", \
    			nRet, inet_ntoa(SourSockAddr.sin_addr), nRealSize, nTime ) ;
    
    		::Sleep ( 1000 ) ;
    	}
    	
    	closesocket ( RawSock ) ;
    	WSACleanup () ;
    
    	return TRUE ;
    }
    
    // 计算ICMP包校验值
    // 参数1：ICMP包缓冲区
    // 参数2：ICMP包长度
    USHORT GetCheckSum ( LPBYTE lpBuf, DWORD dwSize )
    {
    	DWORD	dwCheckSum = 0 ;
    	USHORT* lpWord = (USHORT*)lpBuf ;
    
    	// 累加
    	while ( dwSize > 1 )
    	{
    		dwCheckSum += *lpWord++ ;
    		dwSize -= 2 ;
    	}
    
    	// 如果长度是奇数
    	if ( dwSize == 1 )
    		dwCheckSum += *((LPBYTE)lpWord) ;
    
    	// 高16位和低16位相加
    	dwCheckSum = ( dwCheckSum >> 16 ) + ( dwCheckSum & 0xFFFF ) ;
    
    	// 取反
    	return (USHORT)(~dwCheckSum ) ;
    }

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