연결형 에코 서버 예제

1. 서버 프로그램

 

단순히 클라이언트가 연결을 시도하여 연결이 성사되면  "hellow world from echo server program"

문자를 클라이언트에게 에코한다.  

 

/*
* main.c -- C Test App.
*
* Copyright (C) 2012-2013, 2013 heesoon.kim <chipmaker.tistory.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>

int main(int argc, char *argv[])
{
	struct sockaddr_in server_addr, client_addr;
	int sockfd, acceptfd;
	socklen_t server_addrlen, client_addrlen = 0;
	ssize_t n;
	char ClientAddrStr[INET_ADDRSTRLEN];
	char buffer[128] = "hellow world from echo server program \n";
	
	server_addr.sin_family = AF_INET;
	server_addr.sin_addr.s_addr = inet_addr("192.168.0.2");
	//server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	server_addr.sin_port = htons(5000);
	
	server_addrlen = sizeof(server_addr);
	
	sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
	if(sockfd < 0)
	{
		perror("socket : ");
		exit(EXIT_FAILURE);
	}
	
	if(bind(sockfd, (struct sockaddr *)&(server_addr), server_addrlen) < 0)
	{
		perror("bind : ");
		exit(EXIT_FAILURE);	
	}
	
	if(listen(sockfd, 5) < 0)
	{
		perror("listen : ");
		exit(EXIT_FAILURE);	
	}
	
	while(1)
	{
		acceptfd = accept(sockfd, (struct sockaddr *)&(client_addr), &client_addrlen);
		if(acceptfd < 0)
		{
			perror("listen : ");
			exit(EXIT_FAILURE);	
		}
		else
		{
			// echo fucntion
			write(acceptfd, buffer, strlen(buffer));
			printf("client address = %s \n", inet_ntop(client_addr.sin_family, &(client_addr.sin_addr),
			ClientAddrStr, INET_ADDRSTRLEN));
			close(acceptfd);
		}
	}
	
	close(sockfd);
	
	exit(EXIT_SUCCESS);
}

 

 

2. 클라이언트 프로그램

 

telnet 192.168.0.2 5000 으로 동작을 확인할 수 있다.

 

더 고찰 사항은 서버가 연결해제된 상태에서 연결 시도를 수행할 때 발생하는 시그널 관련하여

클라이언트처리를 확인하기 위해서는 별도의 클라이언트 프로그램 구현이 필요할 것으로 보인다.