week6_network_server.c

/*
pineoc, 2015-04-06
week 6 network programming
echo multi process server & client
+inet_ntoa function
server code
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <arpa/inet.h>
#include <sys/socket.h>
 
#define BUF_SIZE 32
 
void error_handling(char* msg);
void read_childproc(int sig);
 
int main(int argc,char* argv[])
{
	int serv_sock, clnt_sock;
	struct sockaddr_in serv_addr, clnt_addr;

	pid_t pid;//process id
	struct sigaction act;//signal init
	socklen_t addr_size;
	int str_len, state;
	char buf[BUF_SIZE];
	if(argc!=2){
		printf("Usage : %s <port>\n",argv[0]);
		exit(1);
	}

	//signal setting
	act.sa_handler=read_childproc;
	sigemptyset(&act.sa_mask);
	act.sa_flags=0;
	state=sigaction(SIGCHLD,&act,0);

	serv_sock = socket(PF_INET,SOCK_STREAM,0);

	memset(&serv_addr,0,sizeof(serv_addr));
	serv_addr.sin_family=AF_INET;
	serv_addr.sin_addr.s_addr=htonl(INADDR_ANY);
	serv_addr.sin_port=htons(atoi(argv[1]));

	if(bind(serv_sock,(struct sockaddr*)&serv_addr,sizeof(serv_addr))==-1)
		error_handling("bind error");
	if(listen(serv_sock,5)==-1)
		error_handling("listen error");

	while(1)
	{
		addr_size=sizeof(clnt_addr);
		clnt_sock=accept(serv_sock,(struct sockaddr*)&clnt_addr,&addr_size);
		if(clnt_sock==-1)
			continue;
		else
		{
			puts("new client connected...\n");
			char* str_ptr = inet_ntoa(clnt_addr.sin_addr);
			printf("connected client : %s \n",str_ptr);
		}

		pid=fork();//process fork

		if(pid==-1)
		{//fork error
			close(clnt_sock);
			continue;
		}
		if(pid==0)
		{//child
			close(serv_sock);
			while((str_len=read(clnt_sock,buf,BUF_SIZE))!=0)
				write(clnt_sock,buf,str_len);
			close(clnt_sock);
			puts("client disconnected...");
			return 0;
		}
		else//parent
			close(clnt_sock);
	}
	close(serv_sock);
	return 0;
}

void read_childproc(int sig)
{
	pid_t pid;
	int status;
	pid=waitpid(-1,&status,WNOHANG);
	printf("removed proc id: %d \n",pid);
}
void error_handling(char* msg)
{
	fputs(msg,stderr);
	fputc('\n',stderr);
	exit(1);
}

64 line added