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linux 本地通信实例 AF_UNIX

第七根弦 2015 年 3 月 26 日 UC, 进程间通信 发表评论 (0)

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：

C++
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#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：

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#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：

Shell
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./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：

Shell
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./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：

Shell
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./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：

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./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

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