/*
 * TCP/IP server program 
 *    Usage: ./server host_name &
 */

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

#define PORTNO 50001			/* port No. of the socket */

char mesg[] = "hello, world\n";

main(int argc, char *argv[])
{
	struct sockaddr_in server_addr;	/* socked address */
	struct sockaddr_in client_addr;
	struct hostent *host_entry;	/* host address information */
	int server_sid, client_sid;	/* session id of the socket */
	int client_size;

	/* commandline argument check */
	if (argc != 2) {
		fprintf(stderr, "argument mismatch\n");
		exit(1);
	}

	/* create a socket */
	if ((server_sid = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
		fprintf(stderr, "could not make socket\n");
		exit(1);
	}

	/* get host ip address */
	if ((host_entry = gethostbyname(argv[1])) == NULL) {
		fprintf(stderr, "cold not find host\n");
		exit(1);
	}

	/* assign a name to the socket */
	server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(PORTNO);
	memcpy((char *)&server_addr.sin_addr, (char *)host_entry->h_addr,
							 host_entry->h_length);
	if (bind(server_sid, (struct sockaddr *)&server_addr,
						 sizeof(server_addr)) == -1) {
		fprintf(stderr, "could not assign a name to the socket\n");
		exit(1);
	}

	/* listen */
	if (listen(server_sid, 5) == -1) {
		fprintf(stderr, "listen error\n");
		exit(1);
	}
	
	while(1) {
		/* accept */
		client_size = sizeof(client_addr);
		if ((client_sid = accept(server_sid, (struct sockaddr *)&client_addr, 
							&client_size)) == -1) {
			fprintf(stderr, "accept error\n");
			exit(1);
		}

		/* send message */
		if (send(client_sid, mesg, sizeof(mesg), 0) == -1) {
			fprintf(stderr, "send error\n");
			exit(1);
		}

		/* shutdown client socket */
		if (shutdown(client_sid, 2) == -1) {
			fprintf(stderr, "shutdown error\n");
			exit(1);
		}
		close(client_sid);
	}
}