简单的UDP套接字编程例子

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);

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