UDP通信client端和server端

#include <sys/types.h>
#include <sys/socket.h>
#include<pthread.h>
#include <netinet/in.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>

int main(int argc, char **argv)
{
char buff[512];

printf("This is a UDP client\n");
struct sockaddr_in addr;
int sock;

if ( (sock=socket(AF_INET, SOCK_DGRAM, 0)) <0)
{
perror("socket");
exit(1);
}
addr.sin_family = AF_INET;
addr.sin_port = htons(3702);
addr.sin_addr.s_addr = inet_addr("49.123.73.201");
if (addr.sin_addr.s_addr == INADDR_NONE)
{
printf("Incorrect ip address!");
close(sock);
exit(1);
}

while (1)
{
/* 接受用户输入 */
bzero(buff, 512);
if (fgets(buff, 511, stdin) == (char *) EOF)//从键盘输入内容
exit(0);
if( sendto(sock, buff, strlen(buff), 0, (struct sockaddr *)&addr, sizeof(addr)) < 0){
perror("sendto");
close(sock);
break;
}else{
printf("clinet send success!\n");
}

}

return 0;
}

#include <sys/types.h>
#include <sys/socket.h>
#include<pthread.h>
#include <netinet/in.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>

int main(int argc, char **argv)
{
printf("Welcome! This is a UDP server, I can only received message from client and reply with same message\n");

struct sockaddr_in addr;
addr.sin_family = AF_INET;
addr.sin_port = htons(3702);
addr.sin_addr.s_addr = htonl(INADDR_ANY);

int sock;
if ( (sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
{
perror("socket");
exit(1);
}
if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0)
{
perror("bind");
exit(1);
}
char buff[512];
struct sockaddr_in clientAddr;
int n;
int len = sizeof(clientAddr);
while (1)
{
n = recvfrom(sock, buff, 511, 0, (struct sockaddr*)&clientAddr, &len);
if (n>0)
{
buff
= 0;
printf("%s %u says: %s\n", inet_ntoa(clientAddr.sin_addr), ntohs(clientAddr.sin_port), buff);
n = sendto(sock, buff, n, 0, (struct sockaddr *)&clientAddr, sizeof(clientAddr));
if (n < 0)
{
perror("sendto");
break;
}
}
else
{
perror("recv");
break;
}
}
return 0;
}