#include <stdio.h>
#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <arpa/inet.h> 

/* 
	¼öÁ¤»çÇ× : 000.000.000.000 ºÎºÐ¸¸ ¼­¹öÀÇ IP ·Î Àû¾îÁÖ½Ã¸é µË´Ï´Ù.
	
	¾Æ·¡ÀÇ ¼Ò½º´Â Á¦°¡ ¿¾³¯ bit ´Ù´Ò¶§¿¡ TCP ÂÊÀÇ ±âº»°ñ°Ý ¼­¹ö ÂÊÀÔ´Ï´Ù.
	
	±×³É Copy Çϼż­ ¾²½Ã¸é µµÈ÷±¸¿ä¿À, RedHot, Mandrake, Solaris1.x ÀÌ»ó
	¹öÁ¯¿¡¼­ ´Ù µ¹¾Æ°©´Ï´Ù.
	
	Packet Size : 1024 ·Î Çß½À´Ï´Ù.
	                    À̰͵ΠDefine À¸·Î ¸¸µé¾î µÎ¾úÀ¸´Ï±ñ À̺κи¸ ¼öÁ¤ÇÏ½Ã¸é µË´Ï´Ù.	
*/

#define SERVER_PORT 6000
#define SERVER_HOST_ADDR 000.000.000.000

#define MAXLINE 1024 

char *pname;

int main( int argc, char **argv ) 
{ 
	int                         sockfd, newsockfd, clilen, childpid;
	struct sockaddr_in   cli_addr, serv_addr;
		
	pname = argv[0];

        if( ( sockfd = socket( AF_INET, SOCK_STREAM, 0 ) ) < 0 ) {
		perror("¼­¹ö : Socket ERROR");    
		exit(0);
	}

	bzero((char *)&serv_addr, sizeof(serv_addr));
        serv_addr.sin_family = AF_INET; 
        serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); 
        serv_addr.sin_port = htons(SERVER_PORT); 

        if( bind( sockfd, ( struct sockaddr * )&serv_addr, sizeof(serv_addr) ) < 0 ) {
		perror("¼­¹ö : bind ERROR");    
		exit(0);
	}
		
        listen( sockfd, 5 ); 

        printf( "server waiting\n" ); 		
		
        while(1) { 
			
		clilen = sizeof( cli_addr );
		newsockfd = accept( sockfd, (struct sockaddr *) &cli_addr, &clilen );
				
		if( newsockfd < 0 ) { 
			perror("¼­¹ö : ACCEPT ERROR");    
			exit(0);
		}						

		if( ( childpid = fork() ) < 0 ) { 
			perror("¼­¹ö : Fork Error"); 
			exit(0);
		}
		else if( childpid == 0 ) {
			close(sockfd);
                        str_echo( newsockfd );
			exit(0);
		}
				
		close( newsockfd );
        } 
} 

str_echo( int sockfd ) {
	int n;
	char line[MAXLINE];

	for(;;) {
		n = readline( sockfd, line, MAXLINE );
		if(n==0) return;
		else if(n<0) perror("Server:ReadLine Error");

		if( writen(sockfd, line, n) != n )
			perror("strecho : write error");
	}
}

int readline( register int fd, register char *ptr, register int maxlen ) {
	int n, rc;
	char c;

	for( n = 1; n < maxlen; n++ ) {
		if( (rc=read(fd, &c, 1)) == 1 ) {
			*ptr++ = c;
			if(c == '\n') break;
		} else if( rc == 0 ) {
			if( n == 1 ) return(0);
			else break;
		} else return(-1);

	}	

	*ptr = 0;
	return(n);
}

int writen( register int fd, register char *ptr, register int nbytes ) {
	int nleft, nwritten;

	nleft = nbytes;
	while( nleft > 0 ) {
		nwritten = write( fd, ptr, nleft );
		if( nwritten <= 0 ) return(nwritten);

		nleft -= nwritten;
		ptr   += nwritten;
	}

	return( nbytes-nleft);
}