/*********************************************************************************
 *      Copyright:  (C) 2018 LingYun IoT Studio
 *                  All rights reserved.
 *
 *       Filename:  socket_server.c
 *    Description:  This file is UDP socket server example source code.
 *
 *        Version:  1.0.0(10/23/2018)
 *         Author:  Guo Wenxue <guowenxue@gmail.com>
 *      ChangeLog:  1, Release initial version on "2017-10-23 01:41:05 PM"
 *
 ********************************************************************************/

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define LISTEN_PORT          8890
#define BACKLOG              13

int main(int argc, char **argv)
{
    int                     rv = -1;
    int                     sockfd;
    struct sockaddr_in      serv_addr;
    struct sockaddr_in      cli_addr;
    socklen_t               addr_len = sizeof(cli_addr);
    char                    buf[1024];
    int                     reuse = 1;

    /* create UDP socket */
    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if(sockfd < 0 )
    {
        printf("create socket failure: %s\n", strerror(errno));
        return -1;
    }
    printf("socket create fd[%d]\n", sockfd);

    /* fix port can not be used when stop server program and run it again immediately */
    setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));

    /* bind socket server information */
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(LISTEN_PORT);
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    if( bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0 )
    {
        printf("create socket failure: %s\n", strerror(errno));
        return -2;
    }
    printf("socket[%d] bind on port[%d] for all IP address ok\n", sockfd, LISTEN_PORT);

    while(1)
    {
        /* receive message from socket client */
        memset(buf, 0, sizeof(buf));
        if( (rv=recvfrom(sockfd, buf, sizeof(buf), 0, (struct sockaddr *)&cli_addr, &addr_len)) < 0)
        {
            printf("Read data from socket[%d] failure: %s\n", sockfd, strerror(errno));
            break;
        }
        printf("Read [%d] bytes data from client[%s:%d]: %s\n",
                rv, inet_ntoa(cli_addr.sin_addr), ntohs(cli_addr.sin_port), buf);

        /* send message to socket client */
        printf("Reply back to socket client...\n");
        snprintf(buf, sizeof(buf), "Hello, socket client [%s:%d]\n", inet_ntoa(cli_addr.sin_addr), ntohs(cli_addr.sin_port));
        if( (rv=sendto(sockfd, buf, sizeof(buf), 0, (struct sockaddr *)&cli_addr, addr_len)) < 0)
        {
            printf("Reply back to socket client[%d] failure: %s\n", sockfd, strerror(errno));
            break;
        }
        printf("\n");
    }

    close(sockfd);
    return 0;
}