#include<stdio.h>
#include<stdlib.h>
#include<netinet/in.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<sys/time.h>
#include<string.h>
#include<time.h>
#include"struct.h"
 
#define MAX_BUF_SIZE 1500
#define INTERVAL 1000
#define ll long long
#define INF 0x3f3f3f3f 
#define SENDSIZE 48     //设置包大小和发送间隔以控制流量
 
int main(int argc, char* argv[])
{
    if(argc != 3)
    {
        printf("Usage: ./%s IP port_number",argv[0]);
        exit(1);
    } 
    
    char sendbuf[MAX_BUF_SIZE];
    char recvbuf[MAX_BUF_SIZE];
    int sockfd;
    int scale_size = 30;
    int test_num = 1000;
    ll min_time[50];
    struct timeval sendtimeval,send_interval;
    struct sockaddr_in hostaddr;
    struct timeval recvtime;
    long time,receive_time;
    long firsttime,sencondtime;
    struct udp_packet udp_data;
    int len = sizeof(struct sockaddr_in);
    
    
    memset(min_time,INF,sizeof(min_time));
    hostaddr.sin_family = AF_INET;
    hostaddr.sin_port = htons(atoi(argv[2]));
    hostaddr.sin_addr.s_addr = inet_addr(argv[1]);
    send_interval.tv_sec = 0;
    send_interval.tv_usec = INTERVAL;
 
    if ((sockfd = socket(AF_INET,SOCK_DGRAM,0)) < 0){
        printf("Creat Socket Failed !\n");
        exit(1);
    }
    else
        printf("Create Socket Success !\n");
   
    udp_data.seq = 0;
 	
    for(int i=1;i<=scale_size;i++){
    	
    	for(int j=0;j<test_num;j++){
    		send_interval.tv_sec = 0;
	        send_interval.tv_usec = INTERVAL;
	        int temp = select(0, NULL, NULL, NULL, &send_interval);
	        if(temp == -1){
	            continue;
	        }
	        // sleep(1);
	        gettimeofday(&sendtimeval,0);
	        printf("%u  %u\n",sendtimeval.tv_sec,sendtimeval.tv_usec);
	        udp_data.sendtime = 1000000 * sendtimeval.tv_sec + sendtimeval.tv_usec;
	 
	        memset(sendbuf,0x00,MAX_BUF_SIZE);
	        memcpy(sendbuf,&udp_data,sizeof(struct udp_packet));//!!
	        printf("packetsize is : %d\n",SENDSIZE);
	 
	        if ((sendto(sockfd,sendbuf,i*SENDSIZE,0,(struct sockaddr*)&hostaddr,sizeof(hostaddr))) < 0 ){
	            printf("Fail to send the udp packet \n");
	        }
	        else{
	            printf("seq is: %ld \n",udp_data.seq);
	            printf("local send time is: %ld\n",udp_data.sendtime);
	        }
		
			int ret = recvfrom(sockfd,recvbuf,MAX_BUF_SIZE,0,(struct sockaddr *)&hostaddr,&len);
			if(ret > 0){
			    printf("Received data from server!\n", recvbuf);
			}
		
		    gettimeofday(&recvtime,0);
	        receive_time = 1000000*recvtime.tv_sec + recvtime.tv_usec;
	        time = receive_time - udp_data.sendtime;
	        printf("Received interval: %ld\n\n", time);
			
			if( time < min_time[i])	min_time[i] = time;
//			min_time[i] = min(time, min_time[i]);
		   	udp_data.seq++;
		}
        
    }
    close(sockfd);
    return 0;
}   










##server.c

#include<stdio.h>
#include<string.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<stdlib.h>
#include<errno.h>
#include"struct.h"
 
#define MAX_BUF_SIZE 1500
#define SENDSIZE 48
 
int main(int argc,char* argv[])
{
    if (argc != 2)
    {
        printf("./%s portnumber",argv[0]);
        exit(1);
    }
 
    int sockfd;
    long localtime;
    long time;
    long x;
    FILE *fp;
    struct sockaddr_in localaddr,remoteaddr;
    struct timeval recvtime;
    char recvbuf[MAX_BUF_SIZE];
    char * sendbuf;
    struct udp_packet udp_data;
 
    memset(&localaddr,0x00,sizeof(struct sockaddr_in));
    localaddr.sin_family = AF_INET;
    localaddr.sin_port = htons(atoi(argv[1]));
    localaddr.sin_addr.s_addr = htonl(INADDR_ANY);//本机IP
 
    if ((sockfd = socket(AF_INET,SOCK_DGRAM,0)) < 0)
    {
        printf("Create socket failed !\n");
        exit(1);
    }
    else
        printf("Create socket success !\n");
 
    if ((bind(sockfd,(struct sockaddr*)&localaddr,sizeof(localaddr))) < 0)
    {
        printf("Bind port failed !\n");
        exit(1);
    }
    else
        printf("Bind port success !\n");
    
    if ((fp = fopen("./recvdata.txt","w+")) == NULL )
    {
        perror("fopen error");
        exit(1);
    }
    else
        printf("Success to create the receive file!\n");
    int remoteaddr_len = sizeof(struct sockaddr);
    while(1)
    {
 
        if (recvfrom(sockfd,recvbuf,MAX_BUF_SIZE,0,(struct sockaddr*)&remoteaddr,&remoteaddr_len) < 0)
        {
            printf("Fail to receive data!\n");
        }
        else
        {
            printf("receiving... \n");
            struct udp_packet* t_data = (struct udp_packet*)recvbuf;
            gettimeofday(&recvtime,0);
            localtime = 1000000*recvtime.tv_sec + recvtime.tv_usec;
            x=t_data -> sendtime;
            time=localtime-x;
            // printf("Returing1...\n");
            fprintf(fp,"%ld  %ld  %ld    %ld\n", t_data -> seq, localtime, t_data -> sendtime,time);//输出到txt文件方便统计
       	    
	       // printf("Returing2...\n");
    	    sendbuf = "Send Message Success!";
    	    int ret = sendto(sockfd,sendbuf,SENDSIZE,0,(struct sockaddr*)&remoteaddr,sizeof(remoteaddr));
    	    if(ret < 0){
    	    	printf("Failed to return client message!");
    	    }else{
    	    	printf("Return Success!\n\n");

    	    }
       	}
    
    }
    fclose(fp);
    close(sockfd);
    return(0);
}