UDP网络程序设计

udp_server

#include<stdio.h>
#include<sys/socket.h>
#include<string.h>
#include<netinet/in.h>
#define portnum 3333

void main()
{
int n,addrlen;
char buffer[128];
struct sockaddr_in server_addr;
struct sockaddr_in client_addr;
int sockfd;
//1创建套接字
sockfd=socket(AF_INET,SOCK_DGRAM,0)

//2.1设置地址
bzero(&server_addr,sizeof(struct sockaddr_in));
server_addr.sin_family=AF_INET; //IPV4协议族
server_addr.sin_port=htons(portnum);
server_addr.sin_addr.s_addr=htonl(INADDR_ANY);

//2绑定地址
bind(sockfd, (struct sockaddr *)(&server_addr),sizeof(struct sockaddr));

//3接收数据
while(1)
{
addrlen=sizeof(struct sockaddr);
bzero(buffer,sizeof(buffer));
n= recvfrom(sockfd,buffer,128,0,(struct sockaddr *)(&client_addr),&addrlen);
buffer[n]=0; //0是字符串的结束符
printf("server received :%s\n ",buffer);

}

//4结束连接

close(sockfd);

}

udp_client

#include<stdio.h>
#include<sys/socket.h>
#include<string.h>
#include<netinet/in.h>
#define portnum 3333

#define BUF_SIZE 128

int main(int argc, char **argv)
{
char buffer[BUF_SIZE];
struct sockaddr_in server_addr;
int sockfd;

if(argc!=2)
{
printf("usage:%s server_ip\n",argv[0]);
exit(1);

}
//1创建套接字
sockfd=socket(AF_INET,SOCK_DGRAM,0)

//2.1设置地址
bzero(&server_addr,sizeof(struct sockaddr_in));
server_addr.sin_family=AF_INET; //IPV4协议族
server_addr.sin_port=htons(portnum);
server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
inet_aton(argv[1],&server_addr.sin_addr);

//2发送数据

while(1)
{

printf("please input char:\n");
fgets(buffer,128,stdin);

sendto(sockfd,buffer,strlen(buffer),0, (struct sockaddr *)(&server_addr),sizeof(struct sockaddr));
bzero(buffer,sizeof(buffer));

}

//3关闭连接

close(sockfd);
return 0;

}