/*********************************************************************************
 *      Copyright:  (C) 2025 LingYun IoT System Studio
 *                  All rights reserved.
 *
 *       Filename:  usocket_client.c
 *    Description:  This file is UNIX domain socket client example program
 *
 *        Version:  1.0.0(11/07/2025)
 *         Author:  Guo Wenxue <guowenxue@gmail.com>
 *      ChangeLog:  1, Release initial version on "11/07/2025 04:17:02 PM"
 *
 ********************************************************************************/
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>

#define SOCKET_PATH    "/tmp/example.sock" /* UNIX域socke 路径, 与服务器保持一致 */

#define MSG_STR        "Hello, Unix Domain Socket Server!"

int main(int argc, char **argv)
{
    int                     conn_fd = -1;
    int                     rv = -1;
    char                    buf[1024];
    struct sockaddr_un      serv_addr;

    /* 创建 UNIX域名socket(AF_UNIX), 也叫本地套接字(AF_LOCAL)  */
    conn_fd = socket(AF_UNIX /* 或使用 AF_LOCAL */, SOCK_STREAM, 0);
    if(conn_fd < 0)
    {
        printf("create socket failure: %s\n", strerror(errno));
        return -1;
    }

    /* 设置服务器 UNIX域socket 地址(路径) */
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sun_family=AF_UNIX;
    strncpy(serv_addr.sun_path, SOCKET_PATH, sizeof(serv_addr.sun_path)-1);

    /* 连接 UNIX域socket 服务器 */
    if( connect(conn_fd, (struct sockaddr *)&serv_addr, sizeof(serv_addr))  < 0)
    {
        printf("connect to unix domain socket server on \"%s\" failure: %s\n", SOCKET_PATH, strerror(errno));
        return 0;
    }
    printf("connect to unix domain socket server on \"%s\" ok\n", SOCKET_PATH);

    /* 下面的过程与网络 socket 编程完全一致 */

    if( write(conn_fd, MSG_STR, strlen(MSG_STR)) < 0 )
    {
        printf("write data to unix domain socket server on \"%s\" failure: %s\n", SOCKET_PATH, strerror(errno));
        goto cleanup;
    }

    memset(buf, 0, sizeof(buf));
    rv = read(conn_fd, buf, sizeof(buf));
    if(rv < 0)
    {
        printf("Read data from server failure: %s\n", strerror(errno));
        goto cleanup;
    }
    else if( 0 == rv )
    {
        printf("Client connect to server get disconnected\n");
        goto cleanup;
    }

    printf("Read %d bytes data from server: '%s'\n", rv, buf);

cleanup:
    close(conn_fd);
}