/* sender for internet stream demo */

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

#define ENDPACKET "end"
#define MAXLINE 256

help_msg()
{
     printf("format: ists -[d] hostname portno\n");
     printf("           Option: d set debug mode\n");
}

getline(s, lim)
char s[];
int lim;
{
	int c, i;

	for (i=0; i<lim-1 && (c=getchar()) != EOF && c != '\n' ; ++i) 
		s[i] = c;
	if (c == '\n') {
		s[i]= c;
		i++;
	}
	s[i]= '\0';
	return(i);
}

main(argc, argv)
int argc;
char *argv[];
{
	int sock; 
	struct sockaddr_in server;
	struct hostent *hp, *gethostbyname();

	int n = 1;
	int i;
	char buf[1024];
	char fromBuf[1024];
	extern char *optarg;
	extern int   optind;
	int option_exist = 0;
	int c;
	int debug = 0;
	char *rcv_name;  /* receiver's socket name */
	int port_no;

    /* process command line args */
    while ((c=getopt(argc,argv,"d")) != EOF)
    {
        option_exist = 1;
        switch(c)
        {
        case 'd':
 		debug = 1;
		if (debug)
			printf("turn on debug mode.\n");
            	break;

	case '?':
			help_msg();
			exit (1);
	default:
            fprintf (stderr, "unrecognized arg >%s<\n", optarg);
            help_msg();
            exit (1);
	}
}

	rcv_name = argv[optind++];
	if ((port_no = atoi(argv[optind])) < 1025) port_no = 1025;

	if (debug) 
		printf("The receiver's host name is %s, port_no=%d\n", 
				rcv_name, port_no);

	/* create socket on which to sent */
	sock = socket(AF_INET, SOCK_STREAM, 0);
	if (sock < 0) {
		perror("opening stream socket");
		exit(1);
	}
	/* construct name of the socket to send to 
	 * gethostbyname() returns a structure including the network address
	 * of the specified host from /etc/hosts. The port number is taken from
	 * the cmd line
	 * create name structure for the internet socket 
	 * use the name from cmd argument 
	 */
	hp = gethostbyname(rcv_name);
	if (hp == 0) {
		fprintf(stderr, "%s: unknown host",rcv_name);
		exit(2);
	}
	bcopy(hp->h_addr, &server.sin_addr, hp->h_length);
	server.sin_family = AF_INET;
	server.sin_port = htons(port_no);

	if (connect(sock, &server, sizeof(server)) < 0) {
		perror("connecting stream socket");
		exit(1);
	}
	printf("msg for receiver(\"$\" to exit):");
	while ((n = getline(buf, MAXLINE)) > 0) {
		
		/* enter $ to break the connection */
                if (buf[0] ==  '$') {
			printf("exiting...\n");
			close(sock);
			exit(0);
		}
		/*send message */
		if (write(sock, buf, n, 0, 
					&server, sizeof(server)) < 0) 
			perror("writing on stream socket");
		bzero(fromBuf, sizeof(fromBuf));
		if ((n=read(sock, fromBuf, 1024)) < 0) {
			perror("reading on stream socket");
			break;
		} 
		if (n == 0) { 
			printf("receiver breaks the connection, exiting...\n");
			break;
		}
		printf("reply msg=%s\n", fromBuf);
		printf("msg for receiver(\"$\" to exit):");
	}
	close(sock);
}