serverd.c

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

#define BUFF_SIZE 1024

void error_handling(char *message);
int client_socket;

	int main()
	{
		pid_t pid;
	
		if ((pid = fork()) < 0)
		{
			exit(0);
			}
		else if (pid!=0)
		{
			exit(0);
			}

		chdir("/");
		setsid();
	
		int server_socket;
		int client_addr_size;
	 
		struct sockaddr_in server_addr;
	 	struct sockaddr_in client_addr;
	 
		char buff_rcv[BUFF_SIZE+5];
		char buff_snd[BUFF_SIZE+5];
 
		server_socket = socket(PF_INET, SOCK_STREAM, 0);
		if(-1 == server_socket){
		error_handling("socket() error");
		}
 
		memset(&server_addr, 0, sizeof(server_addr));
		server_addr.sin_family		= AF_INET;
		server_addr.sin_port		= htons(4000);
		server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
 
		if(-1 == bind(server_socket, (struct sockaddr*)&server_addr, sizeof(server_addr))){
			error_handling("bind() error");
		}	
 
	while(1)
		{
			if(-1 == listen(server_socket, 5)){
			error_handling("listen() error");
			}
 
			client_addr_size  = sizeof( client_addr);
			client_socket     = accept( server_socket, (struct sockaddr*)&client_addr, &client_addr_size);
 
			if (-1 == client_socket){
			error_handling("accept() error");
			}
 
			read (client_socket, buff_rcv, BUFF_SIZE);
 			printf("receive: %s\n", buff_rcv);
 
			sprintf(buff_snd, "%d : %s", strlen(buff_rcv), buff_rcv);
			write(client_socket, buff_snd, strlen(buff_snd)+1);          // +1: NULL까지 포함해서 전송
			close(client_socket);
			}
	
			sleep(10);
	}

	void error_handling(char* message)
	{
		fputs(message, stderr);
		fputs("\n", stderr);
		close(client_socket);
	}