简单的UDP套接字编程例子-优快云博客

本文提供了一个简单的UDP客户端与服务器程序的实现示例，包括客户端如何通过socket发送消息到服务器，以及服务器如何接收并回应这些消息。示例中详细展示了创建socket、绑定地址、发送与接收数据的过程。

UDP系统调用时序图

简单的UDP例子


/*
 ============================================================================
 Name        : UDPclient.c
 Author      : vestinfo
 Version     : 1.1
 Copyright   : Your copyright notice
 Description : A simple UDP client, Ansi-style
 ============================================================================
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/socket.h>


#define REMOTEPORT 8888
#define REMOTEIP "127.0.0.1"

#define CLIENT_PORT 9999
#define CLIENT_IP "192.168.77.172"

int main(int argc,char *argv[])
{
	int sockfd;
	struct sockaddr_in servaddr;
	struct sockaddr_in clientaddr;
	int addr_len;
	char msg[256];
	int i=0;

	if(( sockfd = socket(AF_INET,SOCK_DGRAM,0))<0)
	{
		perror("error");
		exit(1);
	}

	bzero(&clientaddr, sizeof(clientaddr));
	clientaddr.sin_family=AF_INET;
	clientaddr.sin_port=htons(CLIENT_PORT);
	clientaddr.sin_addr.s_addr=inet_addr(CLIENT_IP);

	if(bind(sockfd, (struct sockaddr *)&clientaddr, sizeof(clientaddr)) < 0)
	{
		perror("error");
		exit(1);
	}

	addr_len=sizeof(struct sockaddr);
	bzero(&servaddr,sizeof(servaddr));

	servaddr.sin_family=AF_INET;
	servaddr.sin_port=htons(REMOTEPORT);
	servaddr.sin_addr.s_addr=inet_addr(REMOTEIP);

	while(1)
	{
		bzero(msg,sizeof(msg));

		read(STDIN_FILENO,msg,sizeof(msg));												//从键盘（终端）键入msg

		sendto(sockfd,msg,sizeof(msg),0,(struct sockaddr *)&servaddr,addr_len);		//发送msg给目的套接字addr

		recvfrom(sockfd,msg,sizeof(msg),0,(struct sockaddr *)&servaddr,&addr_len);//接受目的套接字传来的msg
		printf("Received message from server:%s\n",msg);
	}

}

server

```
/*
```

 ============================================================================

```
 Name        : UDPserver.c
```
```
 Author      : vestinfo
```
```
 Version     : 1.1
```
```
 Copyright   : Your copyright notice
```

 Description : A simple UDP server, Ansi-style

 ============================================================================

```
 */
```
```
#include <stdio.h>
```
```
#include <stdlib.h>
```
```
#include <string.h>
```
```
#include <netinet/in.h>
```
```
#include <arpa/inet.h>
```
```
#include <unistd.h>
```
```
#include <sys/stat.h>
```
```
#include <sys/types.h>
```
```
#include <sys/socket.h>
```
```
#define LOCALPORT 8888
```
```
int main(int argc,char *argv[])
```
```
{
```
```
int sockfd;
```
```
struct sockaddr_in addr;
```
```
char msg[256];
```
```
int addr_len;
```

if((sockfd=socket(AF_INET,SOCK_DGRAM,0)) < 0)

```
    {
```
```
perror("error");
```
```
exit(1);
```
```
    }
```
```
    addr_len=sizeof(struct sockaddr);
```
```
bzero(&addr,sizeof(addr));
```
```
    addr.sin_family = AF_INET;
```
```
    addr.sin_port = htons(LOCALPORT);
```

    addr.sin_addr.s_addr = htonl(INADDR_ANY);

if(bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0)

```
    {
```
```
perror("error");
```
```
exit(1);
```
```
    }
```

printf("UDP server waiting for client...\n");

```
while(1)
```
```
    {
```
```
bzero(msg,sizeof(msg));
```

recvfrom(sockfd,msg,sizeof(msg),0,(struct sockaddr *)&addr,&addr_len);

printf("Received message from:%s\n",inet_ntoa(addr.sin_addr));

printf("The message Received from client:%s",msg);

sendto(sockfd,msg,sizeof(msg),0,(struct sockaddr *)&addr,addr_len);

```
    }
```
```
}
```

转载于:https://www.cnblogs.com/helloweworld/archive/2012/09/30/2709421.html