UPD协议是:无连接,不可靠的数据报传输,对不稳定的网络层采取完全不弥补的策略
它是直接向指定ip和端口的进程发送数据,并且不管对方是否收到。
所以它不稳定,但是速度快,时效性高
UDP比TCP网络通信模型的代码更简单,我们直接看代码就懂了。
server.c
#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<ctype.h>
#include<stdlib.h>
#define SERVER_PORT 8000
int main(void)
{
int sockfd,ret;
char buf[BUFSIZ];
struct sockaddr_in serv_addr,clie_addr;
socklen_t len = sizeof(clie_addr);
sockfd = socket(AF_INET,SOCK_DGRAM,0);//创建套接字
if(sockfd == -1)
{
perror("socket error");
exit(1);
}
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(SERVER_PORT);
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
ret = bind(sockfd,(struct
sockaddr*)&serv_addr,sizeof(serv_addr));//绑定地址结构
if(ret == -1)
{
perror("bind error");
exit(1);
}
while(1)
{
int n = recvfrom(sockfd,buf,sizeof(buf),0,(struct
sockaddr*)&clie_addr,&len);//接收信息
printf("connect sccuess port is %d\n",ntohs(clie_addr.sin_port));
if(n == -1)
{
perror("recvfrom error");
exit(1);
}
for(int i = 0; i < n;i++)
buf[i] = toupper(buf[i]);
sendto(sockfd,buf,n,0,(struct
sockaddr*)&clie_addr,len);//向指定地址发送信息
}
close(sockfd);
return 0;
}
client.c
#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<stdlib.h>
int main(void)
{
int sockfd = socket(AF_INET,SOCK_DGRAM,0);//建立套接字
char buf[BUFSIZ];
struct sockaddr_in serv_addr;
socklen_t serv_addr_len = sizeof(serv_addr);
serv_addr.sin_port = htons(8000);
inet_pton(AF_INET,"127.0.0.1",&serv_addr.sin_addr.s_addr);
serv_addr.sin_family = AF_INET;
while(1)
{
int n = read(STDIN_FILENO,buf,sizeof(buf));
if(n == -1)
{
perror("read error");
exit(1);
}
sendto(sockfd,buf,n,0,(struct
sockaddr*)&serv_addr,serv_addr_len);//向指定地址发送数据
n = recvfrom(sockfd,buf,sizeof(buf),0,NULL,NULL);//接收数据
if( n == -1)
{
perror("recvfrom error");
exit(1);
}
write(STDOUT_FILENO,buf,n);
}
close(sockfd);
return 0;
}