/*
* echo_server.c
* Written by Jonghwa Park
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>

#define BUFSIZE 1024
void error_handling(char *message);

int main(int argc, char *argv[])
{
	int serv_sock; //¼­¹ö ¼ÒÄÏ µð½ºÅ©¸³ÅÍ
	int clnt_sock; //Ŭ¶óÀ̾ðÆ® ¼ÒÄÏ µð½ºÅ©¸³ÅÍ
	char message[BUFSIZE]={0};
	int str_len;
	
	struct sockaddr_in serv_addr; //¼­¹ö ÁÖ¼ÒÁ¤º¸ ±¸Á¶Ã¼
	struct sockaddr_in clnt_addr; //Ŭ¶óÀ̾ðÆ® ÁÖ¼ÒÁ¤º¸ ±¸Á¶Ã¼
	int clnt_addr_size; //Ŭ¶óÀ̾ðÆ® ÁÖ¼Ò Å©±â
	char * serv_ip = "210.93.99.64";

	if (argc != 2)
	{
		printf("Usage: %s <port>\n",argv[0]);
		exit(1);
	}

	/*
	PF_INT : IPv4 ÇÁ·ÎÅäÄÝ »ç¿ë
	1. SOCK_STREAM : ¿¬°áÁöÇâÇü ¼ÒÄÏ(TCP)
	2. SOC_DGRAM : ºñ¿¬°áÁöÇâÇü ¼ÒÄÏ(UDP)
	3. IPPROTO_TCP, OPPROTO_UDP
	*/
	serv_sock = socket(PF_INET, SOCK_STREAM, 0); //¼­¹ö ¼ÒÄÏ »ý¼º


	if (serv_sock == -1)
		error_handling("socket() error");
	printf("¼­¹ö ¼ÒÄÏ »ý¼º : ¼ÒÄÏ Descriptor = %d\n", serv_sock);	

	memset(&serv_addr, 0, sizeof(serv_addr)); //0·Î ÃʱâÈ­
	/*
        ¼­¹ö ÁÖ¼ÒÁ¤º¸ ¼³Á¤	
	1. sin_family : ÁÖ¼Ò Ã¼°è
	2. sin_addr.s_addr : 32 bit Ipv4 ÀÎÅÍ³Ý ÁÖ¼Ò
        3. sin_port : ¼­¹ö Æ÷Æ® ¼³Á¤
	*/
	serv_addr.sin_family= AF_INET;//ipv4;
	serv_addr.sin_addr.s_addr = inet_addr(serv_ip); //
	serv_addr.sin_port = htons(atoi(argv[1])); //

	if (bind(serv_sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) == -1) //
		error_handling("bind() error");
	
	printf("¼ÒÄÏ ÁÖ¼Ò ÇÒ´ç : bind ÇÔ¼ö ¼öÇà ¿Ï·á\n");
	printf("¼ÒÄÏ ÁÖ¼Ò Á¤º¸ : serv_addr.sin_family = %d\n",serv_addr.sin_family);
	printf("¼ÒÄÏ ÁÖ¼Ò Á¤º¸ : serv_addr.sin_addr.s_addr = %s\n",inet_ntoa(serv_addr.sin_addr));
	printf("¼ÒÄÏ ÁÖ¼Ò Á¤º¸ : serv_addr.sin_port = %d\n",ntohs(serv_addr.sin_port));

	if (listen(serv_sock, 5) == -1) //
		error_handling("listen() error");

	printf("¿¬°á ¿äû ´ë±â »óÅ ÁøÀÔ\n");	
	
	clnt_addr_size = sizeof(clnt_addr);
	/*
        ¼­¹ö ¼ÒÄÏÀÌ Å¬¶óÀ̾ðÆ®¿ÍÀÇ ¿¬°áÀ» À§ÇÑ »õ·Î¿î ¼ÒÄÏÀ» Çϳª ¸¸µé¾î ÁØ´Ù
	*/

	clnt_sock = accept(serv_sock, (struct sockaddr*)&clnt_addr, &clnt_addr_size); //
	if (clnt_sock == -1)
		error_handling("accept() error");
	printf("Ŭ¶óÀ̾ðÆ® Á¢¼Ó\n");
	printf("Ŭ¶óÀ̾ðÆ® ÁÖ¼Ò : %s\n",inet_ntoa(clnt_addr.sin_addr)); //
	printf("Ŭ¶óÀ̾ðÆ® Æ÷Æ®: %d\n",ntohs(clnt_addr.sin_port)); //

	/*
         µ¥ÀÌÅÍ ¼ö½Å ¹× Àü¼Û	
        */
	while((str_len=read(clnt_sock,message,BUFSIZE)) != 0)
	{
		printf("Ŭ¶óÀ̾ðÆ®¿ÀºÎÅÍ ¹ÞÀº µ¥ÀÌÅÍ\n");
		printf("%s\n", message);
		write(clnt_sock, message, str_len); //
		printf("Ŭ¶óÀ̾ðÆ®¿¡ µ¥ÀÌÅÍ Àü¼Û\n");
		write(1, message, str_len); //
		memset(message,0,BUFSIZE);
	}
	close(clnt_sock);
	printf("Ŭ¶óÀ̾ðÆ® ¼ÒÄÏ Á¾·á\n");
	

	/*
		Iterative Server 
	
	for (; ; )
	{
			clnt_sock = accept(serv_sock, (struct sockaddr*)&clnt_addr, &clnt_addr_size); //
			if (clnt_sock== -1)
			{
				error_handling("accept() error");
				break;
			}
			printf("====================================================\n");
			printf("Ŭ¶óÀ̾ðÆ® Á¢¼Ó\n");
			printf("Ŭ¶óÀ̾ðÆ® ÁÖ¼Ò : %s\n",inet_ntoa(clnt_addr.sin_addr)); //
			printf("Ŭ¶óÀ̾ðÆ® Æ÷Æ® : %d\n",ntohs(clnt_addr.sin_port)); //
			write(clnt_sock, message, sizeof(message)); //
			printf("Ŭ¶óÀ̾ðÆ®¿¡°Ô µ¥ÀÌÅÍ Àü¼Û\n");
			printf("Ŭ¶óÀ̾ðÆ® ¿¬°á ¼ÒÄÏ Á¾·á ¼ÒÄÏ ¹øÈ£ %d\n", clnt_sock);
			close(clnt_sock); //
	}
	*/

	return 0;
}


void error_handling(char *message)
{
	fputs(message, stderr);
	fputc('\n',stderr);
	exit(1);
}