Savedate.c file

#include <pcap.h>
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <sys/time.h>
#include <signal.h>

FILE * savefp = NULL ;    				// Save the file handle of the packet.
int filelen = 0 ;             		// Record the current file size
#define FILE_SIZE_OUT 10*1024*1024      // File maximum value

struct timeval tpstart, tpend;

long  timeuse =0;
long packets =0;
long all_pkt = 0;
int pkt_len = 128;


void print_stat()
{
	gettimeofday(&tpstart, NULL);
	gettimeofday(&tpend, NULL);
	printf("ens11f0 rec %ld packets\n", packets);
	printf("ens11f0 rec speed %f MB/s\n", packets*pkt_len/(1024*1024*0.1));
	packets = 0;
}

static void signal_handler() 
{
	printf("process terminate : ens11f0 rec %ld packets\n", all_pkt);
}

/*
 Note: Obtain the current system time, and create files in the file name as the file name, and open the file handle.
*/
int open_file_wt()
{
	struct timeval cur_time;
	gettimeofday(&cur_time , NULL);
	struct tm *pTm = NULL;
	char buf[32] = {0};
	pTm = localtime((time_t*)&cur_time.tv_sec);
	sprintf( buf, "%04d%02d%02d%02d%02d%02d%03ld",(1900 + pTm -> tm_year), ( 1 + pTm -> tm_mon ), pTm->tm_mday,
			 pTm -> tm_hour, pTm -> tm_min, pTm -> tm_sec, cur_time.tv_usec/1000);
	if(!savefp)
	{
		savefp = fopen(buf ,"ab+");
		if(savefp == NULL)
		{
			printf("can not open file [%s] \n" , buf);
			exit(0);
		}
		//printf("open file :[%s]\n",buf);
		filelen = 0;
	}
	return 0;
}


/*
 Note: This function is registered in PCAP_LOOP, and libcap will come up with the data captured by this function.
			 Len members in Data_HEAD save the length of the currently captured by the data packet.
			 Packet_data is the saving address that currently captures the data packet.
*/
void packet_handler(unsigned char  * user, const struct pcap_pkthdr * data_head,const unsigned char  * packet_data)
{
	packets++;
	all_pkt++;
	gettimeofday(&tpend, NULL);
	timeuse = 1000000 * (tpend.tv_sec - tpstart.tv_sec) + tpend.tv_usec - tpstart.tv_usec;
	if (unlikely(timeuse >= 1000000))
	{
		print_stat();
	}
	filelen +=  data_head->len;     // data_head-> len: The length of the packet is captured.
	if(filelen > FILE_SIZE_OUT)     // The current file is too large and rewritten
	{
		fclose(savefp);               // Close the file
		savefp = NULL;
		open_file_wt();               // Re -open new files
		filelen += data_head->len;
	}
	fwrite(packet_data , data_head->len , 1 , savefp);    // Save the packet.
	return ;
	
}

/*
 Note: Open the designated network card device, register a callback function
*/
int get_packet(char  *device)
{
    pcap_t *adhandle;
    char errbuf[1024];
    if ( (adhandle= pcap_open_live(device,65535,  1 ,1000, errbuf) ) == NULL)     // Open the designated network card device
    {
        printf("\nUnable to open the adapter. %s is not supported by LibPcap\n" ,device );
        return 0;
    }
		pcap_loop(adhandle, 0, packet_handler, NULL);                     // Register a callback function packet_handler
		pcap_close(adhandle);  

    return 0;
}




int main(int argc , char *argv[])
{
	signal(SIGINT, signal_handler);
	open_file_wt();
	gettimeofday(&tpstart, NULL);
	if(argc-1)
		get_packet(argv[1]);
	else
		get_packet("eth0");
	return 0;
}

Makefile file

all:
	gcc -Wall savedate.c -lpcap -osavedate

Executing make will generate a SaveData executable file