WinPcap发送接收裸包（一）

约定不等于承诺〃 2022-08-06 13:20 198阅读 0赞

需求：在windows平台上实现和硬件的通信，环境局域网，实时性要求比较高。

设计：优先考虑在数据链路层进行数据的处理，采用自定义裸包的方式肯定是最好的，速度效率最高了。

首先想到的是socket，TCP或者UDP，不过这个都是传输层的协议了，不考虑。还有一种是用raw socket实现，但是也不够好，它只能到网络层。最终选择了winpcap。

下面就将使用winpcap实现数据裸包的发送接收的方法进行分享：

裸包的结构如下：以太网帧头+自定义数据

以太网帧头定义如下：

typedef struct eth_header
    {
    	unsigned char DestMac[6];	//dest MAC
    	unsigned char SrcMac[6];
    	unsigned short Etype;	//类型
    }eth_header;

代码如下：

#include <stdlib.h>
    #include <stdio.h>
    #include <pcap.h> 
    
    #define ETHERTYPE_IP            0x0800          /* IP */  
    
    typedef struct eth_header
    {
    	unsigned char DestMac[6];
    	unsigned char SrcMac[6];
    	unsigned short Etype;
    }eth_header;
    
    int main(int argc, char **argv)
    {
    	pcap_t *fp;
    	char errbuf[PCAP_ERRBUF_SIZE];
    	int i;
    	eth_header m_ethHeader;
    	char strMessage[]={"hello world!"};
    	int index;
    	char SendBuffer[1024];
    	
    	/* Check the validity of the command line */
    	if (argc != 2)
    	{
    		printf("usage: %s interface", argv[0]);
    		return 1;
    	}
        
    	/* Open the adapter */
    	if ((fp = pcap_open_live(argv[1],		// name of the device
    							 65536,			// portion of the packet to capture. It doesn't matter in this case 
    							 1,				// promiscuous mode (nonzero means promiscuous)
    							 1000,			// read timeout
    							 errbuf			// error buffer
    							 )) == NULL)
    	{
    		fprintf(stderr,"\nUnable to open the adapter. %s is not supported by WinPcap\n", argv[1]);
    		return 2;
    	}
    
    	/* Supposing to be on ethernet, set mac destination to 1:1:1:1:1:1 */
    	//填充网卡报头
    	m_ethHeader.DestMac[0]=0x00;
    	m_ethHeader.DestMac[1]=0x1e;
    	m_ethHeader.DestMac[2]=0x4f;
    	m_ethHeader.DestMac[3]=0xb7;
    	m_ethHeader.DestMac[4]=0x50;
    	m_ethHeader.DestMac[5]=0x94;
    
    	//28:d2:44:28:74:f9
    	m_ethHeader.SrcMac[0]=0x28;
    	m_ethHeader.SrcMac[1]=0xd2;
    	m_ethHeader.SrcMac[2]=0x44;
    	m_ethHeader.SrcMac[3]=0x28;
    	m_ethHeader.SrcMac[4]=0x74;
    	m_ethHeader.SrcMac[5]=0xf9;
    
    	m_ethHeader.Etype=ETHERTYPE_IP;
            //拷贝数据到发送字符中
    	memcpy(SendBuffer,&m_ethHeader,sizeof(m_ethHeader));
    	index=sizeof(m_ethHeader);
    	memcpy(&SendBuffer[index],strMessage,sizeof(strMessage));
    	index+=sizeof(strMessage);
    
    	/* Send down the packet */
    	for(i=0;i<10;i++)
    	{
    		if (pcap_sendpacket(fp,	// Adapter
    			SendBuffer,				// buffer with the packet
    			index					// size
    			) != 0)
    		{
    			fprintf(stderr,"\nError sending the packet: %s\n", pcap_geterr(fp));
    			return 3;
    		}
    	    printf("send successed!\n");
    		Sleep(1000);
    	}
    
    	pcap_close(fp);	
    	return 0;
    }