/* 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 -[dn] hostname portno\n");
     printf("           Option: d set debug mode\n");
     printf("           Option: n set the number of messages sent\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;
   int nBytesRcvd;
   char toBuf[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,"dn:")) != EOF)
    {
        option_exist = 1;
        switch(c) {
        case 'd':
           debug = 1;
           if (debug)
              printf("turn on debug mode.\n");
           break;
        case 'n':
           if ((n = atoi(optarg)) < 1) n = 1;
           if (debug)
              printf("The number of msgs sent is set to %d\n", 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);
   }
   memcpy(&server.sin_addr, hp->h_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);
   }
   /*send message */
   for (i=0; i<n; i++) {
      sprintf(toBuf, "packet %d!\n", i);
      if (debug) printf("Sending msg: %s", toBuf);
      if (write(sock, toBuf, strlen(toBuf)) < 0) 
         perror("writing on stream socket");
      if ((nBytesRcvd=read(sock, fromBuf, 1024)) < 0) {
         perror("reading on stream socket");
         break;
      } 
      if (nBytesRcvd == 0) { 
         printf("receiver breaks the connection, exiting...\n");
         break;
      }
      if (debug) {
         printf("number of bytes received=%d\n", nBytesRcvd);
         printf("received ack msg=%s\n", fromBuf);
      }  
   }
   close(sock);
}