#include <stdio.h>  //printf
#include <arpa/inet.h>  //inet_addr htons
#include <sys/types.h>
#include <sys/socket.h>  //socket bind listen accept connect
#include <netinet/in.h>  //sockaddr_in
#include <stdlib.h>  //exit
#include <unistd.h>  //close
#include <string.h>

#define N 128
#define errlog(errmsg) do{\
							perror(errmsg);\
							printf("%s --> %s --> %d\n", __FILE__, __func__, __LINE__);\
							exit(1);\
						 }while(0)

int main(int argc, const char *argv[])
{
	int sockfd, acceptfd;
	struct sockaddr_in serveraddr, clientaddr;
	socklen_t addrlen = sizeof(serveraddr);
	char buf[N] = {};
	ssize_t bytes;

	if(argc < 3)
	{
		printf("您輸入的引數太少了: %s <ip> <port>\n", argv[0]);
		exit(1);
	}

	//第一步：建立套接字
	if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
	{
		errlog("fail to socket");
	}

	//第二步：填充伺服器網路資訊結構體
	//inet_addr：將點分十進位制ip地址轉化為網路位元組序的整型資料
	//htons：將主機位元組序轉化為網路位元組序
	//atoi：將數字型字串轉化為整型資料
	serveraddr.sin_family = AF_INET;
	serveraddr.sin_addr.s_addr = inet_addr(argv[1]);
	serveraddr.sin_port = htons(atoi(argv[2]));

	//第三步：將套接字域網路資訊結構體繫結
	if(bind(sockfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr)) < 0)
	{
		errlog("fail to bind");
	}

	//第四步：將套接字設定為監聽狀態
	if(listen(sockfd, 5) < 0)
	{
		errlog("fail to listen");
	}

	//第五步：阻塞等待客戶端的連線請求
	if((acceptfd = accept(sockfd, (struct sockaddr *)&clientaddr, &addrlen)) < 0)
	{
		errlog("fail to accept");
	}

	//列印客戶端的ip地址、埠號
	printf("%s --- %d\n", inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));

	while(1)
	{
		if((bytes = recv(acceptfd, buf, N, 0)) < 0)
		{
			errlog("fail to recv");
		}
		else if(bytes == 0)
		{
			printf("NO DATA\n");
			exit(1);
		}
		else 
		{
			if(strncmp(buf, "quit", 4) == 0)
			{
				printf("client is quited ...\n");
				break;
			}
			else
			{
				printf("client : %s\n", buf);

				strcat(buf, " *_*");

				if(send(acceptfd, buf, N, 0) < 0)
				{
					errlog("fail to send");
				}
			}
		}
	}

	close(acceptfd);
	close(sockfd);
	
	return 0;
}