Linux下的通信时延测试程序

今天段老师在网络软件设计课上布置了一个题目。

要求是Windows环境，现在在Linux环境下实现。

运行C/S模式的2个程序，使用UDP协议，发送10次，计算平均时延。

服务器程序如下：

#include <sys/socket.h> // for functions for socket
#include <netinet/in.h> // for struct sockaddr_in
#include <stdlib.h>
#include <memory.h> // for memset
#include <stdio.h> // for perror
#include <errno.h> // for errno

#define BUFLEN 100
int main(void)
{
int listenfd;
char buf[BUFLEN];
socklen_t len;
struct sockaddr_in serv, cli;

if ((listenfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
{ // use udp
perror("socket");
exit(EXIT_FAILURE);
}

memset(&serv, 0, sizeof(serv)); // clear
serv.sin_family = AF_INET; // use IPv4
// Listen any ip address and use network
// byte order
serv.sin_addr.s_addr = htonl(INADDR_ANY);
serv.sin_port = htons(9877); // Listen port 9877

if (bind(listenfd, (struct sockaddr*)&serv, sizeof(serv)) < 0)
{ // bind the socket to the server address
perror("bind");
exit(EXIT_FAILURE);
}

for ( ; ; )
{
len = sizeof(cli);
if ((recvfrom(listenfd, buf, BUFLEN, 0,
(struct sockaddr*)&cli, &len)) < 0)
{  // recvfrom the listenfd
// put the message into buf
// no flags (4th argument 0)
// save the client address and length
if (errno == EINTR || errno == EAGAIN)
continue;
perror("recvfrom");
exit(EXIT_FAILURE);
}
if ((sendto(listenfd, "Got it!", 10, 0,
(struct sockaddr*)&cli, len)) < 0)
{  // send the message back
// send message "Got it!" back
if (errno == EINTR || errno == EAGAIN)
continue;
perror("sendto");
exit(EXIT_FAILURE);
}
}

return 0;
}

客户端程序如下：

#include <sys/socket.h> // for functions for socket
#include <arpa/inet.h> // for inet_pton
#include <netinet/in.h> // for struct sockaddr_in
#include <stdlib.h>
#include <memory.h> // for memset
#include <stdio.h> // for perror
#include <errno.h> // for errno
#include <time.h>

#define SENDTIMES 10
#define BUFLEN 100
int main(int argc, char* argv[])
{
struct sockaddr_in serv;
int sockfd;
int i;
clock_t start, finish;
double duration, total = 0;
char buf[BUFLEN];

if (argc != 2)
{
fprintf(stderr, "Usage: ./udpcli <IPADDR>\n");
exit(EXIT_FAILURE);
}

if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
{ // use udp
perror("socket");
exit(EXIT_FAILURE);
}

memset(&serv, 0, sizeof(serv));
serv.sin_family = AF_INET;
serv.sin_port = htons(9877);
if ((inet_pton(AF_INET, argv[1],
&serv.sin_addr)) == 0)
{ // read the string to the structrue
perror("inet_pton");
exit(EXIT_FAILURE);
}

again:
if ((connect(sockfd,
(struct sockaddr*)&serv, sizeof(serv))) < 0)
{ // this connect is for catch the
  // error ICMP packets
if (errno == EINTR || errno == EAGAIN)
goto again;
perror("connect");
exit(EXIT_FAILURE);
}

for (i = 0; i < SENDTIMES; ++i)
{
printf("Send %d messages.\n", i + 1);
start = clock();
again2:
if ((sendto(sockfd, "A message!", 20, 0,
(struct sockaddr*)&serv, sizeof(serv))) < 0)
{
if (errno == EINTR)
goto again2;
perror("sendto");
exit(EXIT_FAILURE);
}
again3:
if ((recvfrom(sockfd, buf, BUFLEN, 0,
NULL, NULL)) < 0)
{
if (errno == EINTR)
goto again3;
perror("recvfrom");
exit(EXIT_FAILURE);
}
finish = clock();
duration = finish - start;
printf("Spend time: %fms\n", duration / CLOCKS_PER_SEC * 1000);
total += duration;
}

printf("\nAverage time: %fms\n", total / SENDTIMES / CLOCKS_PER_SEC * 1000);
return 0;
}