WinPcap发送接收裸包（二）

迈不过友情╰ 2022-08-06 13:20 135阅读 0赞

上一篇说了如何发送裸包，下面看如何接收数据包。

代码很简单，就不多介绍了。

#ifdef _MSC_VER
    /*
     * we do not want the warnings about the old deprecated and unsecure CRT functions
     * since these examples can be compiled under *nix as well
     */
    #define _CRT_SECURE_NO_WARNINGS
    #endif
    
    #include "pcap.h"
    
    
    typedef struct eth_header
    {
    	unsigned char DestMac[6];
    	unsigned char SrcMac[6];
    	unsigned short Etype;
    }eth_header;
    
    /* prototype of the packet handler */
    void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data);
    void formatMACToStr(LPSTR lpHWAddrStr,const unsigned char *HWAddr);
    
    int main()
    {
    	pcap_if_t *alldevs;
    	pcap_if_t *d;
    	int inum;
    	int i=0;
    	pcap_t *adhandle;
    	char errbuf[PCAP_ERRBUF_SIZE];
    	u_int netmask;
    	char packet_filter[] ="ether src 28:d2:44:28:74:f9" /*"ip and udp"*/;
    	struct bpf_program fcode;
    	
    	/* Retrieve the device list */
    	if(pcap_findalldevs(&alldevs, errbuf) == -1)
    	{
    		fprintf(stderr,"Error in pcap_findalldevs: %s\n", errbuf);
    		exit(1);
    	}
    	
    	/* Print the list */
    	for(d=alldevs; d; d=d->next)
    	{
    		printf("%d. %s", ++i, d->name);
    		if (d->description)
    			printf(" (%s)\n", d->description);
    		else
    			printf(" (No description available)\n");
    	}
    
    	if(i==0)
    	{
    		printf("\nNo interfaces found! Make sure WinPcap is installed.\n");
    		return -1;
    	}
    	
    	printf("Enter the interface number (1-%d):",i);
    	scanf("%d", &inum);
    	
    	/* Check if the user specified a valid adapter */
    	if(inum < 1 || inum > i)
    	{
    		printf("\nAdapter number out of range.\n");
    		
    		/* Free the device list */
    		pcap_freealldevs(alldevs);
    		return -1;
    	}
    
    	/* Jump to the selected adapter */
    	for(d=alldevs, i=0; i< inum-1 ;d=d->next, i++);
    	
    	/* Open the adapter */
    	if ((adhandle= pcap_open_live(d->name,	// name of the device
    							 65536,			// portion of the packet to capture. 
    											// 65536 grants that the whole packet will be captured on all the MACs.
    							 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");
    		/* Free the device list */
    		pcap_freealldevs(alldevs);
    		return -1;
    	}
    	
    	/* Check the link layer. We support only Ethernet for simplicity. */
    	if(pcap_datalink(adhandle) != DLT_EN10MB)
    	{
    		fprintf(stderr,"\nThis program works only on Ethernet networks.\n");
    		/* Free the device list */
    		pcap_freealldevs(alldevs);
    		return -1;
    	}
    	
    	if(d->addresses != NULL)
    		/* Retrieve the mask of the first address of the interface */
    		netmask=((struct sockaddr_in *)(d->addresses->netmask))->sin_addr.S_un.S_addr;
    	else
    		/* If the interface is without addresses we suppose to be in a C class network */
    		netmask=0xffffff; 
    
    
    	//compile the filter
    	if (pcap_compile(adhandle, &fcode, packet_filter, 1, netmask) <0 )
    	{
    		fprintf(stderr,"\nUnable to compile the packet filter. Check the syntax.\n");
    		/* Free the device list */
    		pcap_freealldevs(alldevs);
    		return -1;
    	}
    	
    	//set the filter
    	if (pcap_setfilter(adhandle, &fcode)<0)
    	{
    		fprintf(stderr,"\nError setting the filter.\n");
    		/* Free the device list */
    		pcap_freealldevs(alldevs);
    		return -1;
    	}
    	
    	printf("\nlistening on %s...\n", d->description);
    	
    	/* At this point, we don't need any more the device list. Free it */
    	pcap_freealldevs(alldevs);
    	
    	/* start the capture */
    	pcap_loop(adhandle, 0, packet_handler, NULL);
    	
    	return 0;
    }
    
    /* Callback function invoked by libpcap for every incoming packet */
    void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data)
    {
    	struct tm *ltime;
    	char timestr[16];
    	time_t local_tv_sec;
    	eth_header *pEthHeader;
    	char strMac[50];
    	char *pRecBuffer;
    
    	/*
    	 * unused parameter
    	 */
    	(VOID)(param);
    
    	/* convert the timestamp to readable format */
    	local_tv_sec = header->ts.tv_sec;
    	ltime=localtime(&local_tv_sec);
    	strftime( timestr, sizeof timestr, "%H:%M:%S", ltime);
    
    	/* print timestamp and length of the packet */
    
    	pEthHeader=(eth_header *)pkt_data;
    	formatMACToStr(strMac,pEthHeader->SrcMac);
    	printf("%s.%.6d len:%d ", timestr, header->ts.tv_usec, header->len);
    	printf("\nSrcMac is:%s-->",strMac);
    	formatMACToStr(strMac,pEthHeader->DestMac);
    	printf("destMac is:%s\n",strMac);
    	printf("eth type is:\t%d\n",ntohs(pEthHeader->Etype));
    
        pRecBuffer=(char *)(pkt_data+14);
    	printf("data is:\t%s\n",pRecBuffer);
    	
    }
    
    /****************************************************************************
    *	Name & Params::
    *			formatMACToStr
    *			(
    *				LPSTR lpHWAddrStr :		 要显示到list上的字符串
    *				unsigned char *HWAddr :  传入的MAC字符串
    *			)
    *	Purpose:
    *			将用户输入的MAC地址字符转成相应格式
    ****************************************************************************/
    void formatMACToStr(LPSTR lpHWAddrStr,const unsigned char *HWAddr)
    {
    	int i;
    	short temp;
    	char szStr[3];
    	
    	strcpy(lpHWAddrStr, "");
    	for (i=0; i<6; ++i)
    	{
    		temp = (short)(*(HWAddr + i));
    		_itoa(temp, szStr, 16);
    		if (strlen(szStr) == 1)	strcat(lpHWAddrStr, "0");
    		strcat(lpHWAddrStr, szStr);
    		if (i<5)	strcat(lpHWAddrStr, ":");         // 加上 - 
    	}
    }