linux 本地通信实例 AF_UNIX

程序说明：

程序里包含服务端和客户端两个程序，它们之间使用 AF_UNIX 实现本机数据流通信。使用 AF_UNIX 域实际上是使用本地 socket 文件来通信。

服务器端代码：



#include <sys/types.h>

#include <sys/socket.h>

#include <stdio.h>

#include <sys/un.h>

#include <unistd.h>

#include <stdlib.h>

int main (int argc, char *argv[])

{

int server_sockfd, client_sockfd;

int server_len, client_len;

struct sockaddr_un server_address; /*声明一个UNIX域套接字结构*/

struct sockaddr_un client_address;

int i, bytes;

char ch_send, ch_recv;

unlink ("server_socket"); /*删除原有server_socket对象*/

/*创建 socket, 通信协议为AF_UNIX, SCK_STREAM 数据方式*/

server_sockfd = socket (AF_UNIX, SOCK_STREAM, 0);

/*配置服务器信息(通信协议)*/

server_address.sun_family = AF_UNIX;

/*配置服务器信息(socket 对象)*/

strcpy (server_address.sun_path, "server_socket");

/*配置服务器信息(服务器地址长度)*/

server_len = sizeof (server_address);

/*绑定 socket 对象*/

bind (server_sockfd, (struct sockaddr *)&server_address, server_len);

/*监听网络,队列数为5*/

listen (server_sockfd, 5);

printf ("Server is waiting for client connect...\n");

client_len = sizeof (client_address);

/*接受客户端请求; 第2个参数用来存储客户端地址; 第3个参数用来存储客户端地址的大小*/

/*建立(返回)一个到客户端的文件描述符,用以对客户端的读写操作*/

client_sockfd = accept (server_sockfd, (struct sockaddr *)&server_address, (socklen_t*)&client_len);

if (client_sockfd == -1) {

perror ("accept");

exit (EXIT_FAILURE);

}

printf ("The server is waiting for client data...\n");

for (i = 0, ch_send = '1'; i < 5; i++, ch_send++) {

if ((bytes = read (client_sockfd, &ch_recv, 1)) == -1) {

perror ("read");

exit (EXIT_FAILURE);

}

printf ("The character receiver from client is %c\n", ch_recv);

sleep (1);

if ((bytes = write (client_sockfd, &ch_send, 1)) == -1) {

perror ("read");

exit (EXIT_FAILURE);

}

}

close (client_sockfd);

unlink ("server socket");

}

客户端代码：



#include <sys/types.h>

#include <sys/socket.h>

#include <stdio.h>

#include <sys/un.h>

#include <unistd.h>

#include <stdlib.h>

int main (int argc, char *argv[])

{

struct sockaddr_un address;

int sockfd;

int len;

int i, bytes;

int result;

char ch_recv, ch_send;

/*创建socket,AF_UNIX通信协议,SOCK_STREAM数据方式*/

if ((sockfd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {

perror ("socket");

exit (EXIT_FAILURE);

}

address.sun_family = AF_UNIX;

strcpy (address.sun_path, "server_socket");

len = sizeof (address);

/*向服务器发送连接请求*/

result = connect (sockfd, (struct sockaddr *)&address, len);

if (result == -1) {

printf ("ensure the server is up\n");

perror ("connect");

exit (EXIT_FAILURE);

}

for (i = 0, ch_send = 'A'; i < 5; i++, ch_send++) {

if ((bytes = write(sockfd, &ch_send, 1)) == -1) { /*发消息给服务器*/

perror ("write");

exit (EXIT_FAILURE);

}

sleep (2); /*休息二秒钟再发一次*/

if ((bytes = read (sockfd, &ch_recv, 1)) == -1) { /*接收消息*/

perror ("read");

exit (EXIT_FAILURE);

}

printf ("receive from server data is %c\n", ch_recv);

}

close (sockfd);

return (0);

}

程序说明：

先运行服务器端，然后再运行客户端可以在两边同时看到输出。服务器端先运行后会出现如下提示：



./sock_local_server

Server is waiting for client connect...

这表示，服务器端已经被阻塞到到 accept() 这里，服务器就在此等候客户端的连接。

如果不是先运行服务器端，而直接运行客户端，那么客户端会提示：



./sock_local_client

ensure the server is up

connect: Connection refused

提示服务器没有准备好，连接被拒绝，从而直接退出程序。

如果服务器和客户端依次运行，可以在两边看到输出：

服务器端：



./sock_local_server

Server is waiting for client connect...

The server is waiting for client data...

The character receiver from client is A

The character receiver from client is B

The character receiver from client is C

The character receiver from client is D

The character receiver from client is E

客户端：



./sock_local_client

receive from server data is 1

receive from server data is 2

receive from server data is 3

receive from server data is 4

receive from server data is 5