Unix Domain Socket 域套接字实现

主要注意流程：

STREAM SOCKET： 

Server :  socket() --->  bind() ---> listen()  ---> accept()

Client:    scoket() ---> connect()

参考文章一篇就够： http://troydhanson.github.io/misc/Unix_domain_sockets.html
自己写的 一个 Server 和 一个Client：

//Server
//
// unix_domain_server.c
// UnixDomainServer
//
// Created by gtliu on 7/11/13.
// Copyright (c) 2013 GT. All rights reserved.
//

#include "MITLogModule.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <stddef.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>

#define FUNC_FAIL -1
#define FUNC_SUCCESS 0
#define SOCKADDR_UN_SUN_PATH_MAX_LEN 103 // 104 - 1
#define SER_ACCEPT_CON_NUM 1

/**
* Create a server endpoint of a connection.
*
* @param scok_path: the unix domain socket path
* @return return the file descirption if all ok, <0 on err
*/
int create_serv_listen(const char *sock_path)
{
size_t path_len = strlen(sock_path);
if (path_len == 0) {
MITLogWrite(MITLOG_LEVEL_ERROR, "socket path can't be empty");
return FUNC_FAIL;
} else if (path_len > SOCKADDR_UN_SUN_PATH_MAX_LEN) {
MITLogWrite(MITLOG_LEVEL_ERROR, "socket path length must less than%d", SOCKADDR_UN_SUN_PATH_MAX_LEN);
return FUNC_FAIL;
}

int fd = 0, size = 0;
struct sockaddr_un server_un;
memset(&server_un, 0, sizeof(server_un));
server_un.sun_family = AF_UNIX;
strncpy(server_un.sun_path, sock_path, sizeof(server_un.sun_path) - 1);

if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
MITLogWrite(MITLOG_LEVEL_ERROR, "socket() faild:%s", strerror(errno));
return FUNC_FAIL;
}
/* in case it already exists */
unlink(sock_path);

size = offsetof(struct sockaddr_un, sun_path) + strlen(server_un.sun_path);
if (bind(fd, (struct sockaddr *)&server_un, size) < 0) {
MITLogWrite(MITLOG_LEVEL_ERROR, "bind() failed:%s", strerror(errno));
close(fd);
return FUNC_FAIL;
}

if (listen(fd, 0) < 0) {
MITLogWrite(MITLOG_LEVEL_ERROR, "listen() failed:%s", strerror(errno));
close(fd);
return FUNC_FAIL;
}

return fd;
}

/**
* Accept a client's connection and return the relative file descriptor.
*
* @param listen_fd: the server socket file descriptor
* @return return the file descirption if all ok, <0 on err
*/
int serv_accept(int listen_fd)
{
int child_fd = 0, len = 0;
struct sockaddr_un income_un;
len = sizeof(income_un);

if ((child_fd = accept(listen_fd, (struct sockaddr *)&income_un, &len)) < 0) {
MITLogWrite(MITLOG_LEVEL_ERROR, "accept() failed:%s", strerror(errno));
/* often errno=EINTR, if signal caught */
return FUNC_FAIL;
}
return child_fd;
}

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

MITLogOpen("unix_domain_server");

char *sock_path = "/tmp/domain_socket_one";
if (argc > 1) {
sock_path = (char *) argv[1];
}

MITLogWrite(MITLOG_LEVEL_COMMON, "Starting the server...");
int listen_fd = create_serv_listen(sock_path);
if (listen_fd == FUNC_FAIL) {
return FUNC_FAIL;
}

MITLogWrite(MITLOG_LEVEL_COMMON, "Wait for the client... listen_fd:%d", listen_fd);
int child_fd = serv_accept(listen_fd);
if (child_fd == FUNC_FAIL) {
close(listen_fd);
return FUNC_FAIL;
}

char recv_buffer[1024] = {0};
while (1) {
MITLogWrite(MITLOG_LEVEL_COMMON, "Wait for the message...");
if(read(child_fd, recv_buffer, sizeof(recv_buffer) - 1) > 0) {
printf("Recieve message:%s\n", recv_buffer);
}
sleep(2);
}

MITLogClose();
return 0;
}

//Client
//
//  main.c
//  UnixDomainClient
//
//  Created by gtliu on 7/11/13.
//  Copyright (c) 2013 GT. All rights reserved.
//

#include "MITLogModule.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <stddef.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/stat.h>

#define FUNC_FAIL                           -1
#define FUNC_SUCCESS                        0
#define SOCKADDR_UN_SUN_PATH_MAX_LEN        103  // 104 - 1
#define SER_ACCEPT_CON_NUM                  1

/**
* Create a server endpoint of a connection.
*
* @param  scok_path: the unix domain socket path
* @return return the file descirption if all ok, <0 on err
*/
int client_connection(const char *sock_path)
{
size_t path_len = strlen(sock_path);
if (path_len == 0) {
MITLogWrite(MITLOG_LEVEL_ERROR, "socket path can't be empty");
return FUNC_FAIL;
} else if (path_len > SOCKADDR_UN_SUN_PATH_MAX_LEN) {
MITLogWrite(MITLOG_LEVEL_ERROR, "socket path length must less than%d", SOCKADDR_UN_SUN_PATH_MAX_LEN);
return FUNC_FAIL;
}

int fd = 0, len = 0;
if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
MITLogWrite(MITLOG_LEVEL_ERROR, "socket() faild:%s", strerror(errno));
return FUNC_FAIL;
}

struct sockaddr_un client_un;
memset(&client_un, 0, sizeof(client_un));
client_un.sun_family = AF_UNIX;
strncpy(client_un.sun_path, sock_path, sizeof(client_un.sun_path) - 1);

len = offsetof(struct sockaddr_un, sun_path) + strlen(client_un.sun_path);
if ((connect(fd, (struct sockaddr *)&client_un, len)) < 0) {
MITLogWrite(MITLOG_LEVEL_ERROR, "connect() failed:%s", strerror(errno));
close(fd);
return FUNC_FAIL;
}

return fd;
}

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

MITLogOpen("unix_domain_client");

char *sock_path = "/tmp/domain_socket_one";
if (argc > 1) {
sock_path = (char *) argv[1];
}

MITLogWrite(MITLOG_LEVEL_COMMON, "Starting the client...");
int client_fd = client_connection(sock_path);
if (client_fd == FUNC_FAIL) {
return FUNC_FAIL;
}

for (int i=1; i < 100; ++i) {
MITLogWrite(MITLOG_LEVEL_COMMON, "Send message to server...");
char msg[256] = {0};
sprintf(msg, "client message :%d", i);
if(write(client_fd, msg, strlen(msg)) > 0) {
MITLogWrite(MITLOG_LEVEL_COMMON, "Send message :%d success", i);
}
sleep(2);
}

MITLogClose();
return 0;
}