/* server for inet stream demo */
/* cmd format: istr <receive-sockect-name> */

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

#define TRUE 1
#define MAXLINE 256

/* this program creates a socket and then begin an infinite loop.  Each time
 * through the loop, it accepts a connection, prints out messages from it,
 * and then ask for reply message from the user.
 * When the connection breaks, or a termination messgage come through, the
 * program accepts a new connection. 
 */

void printsockaddr(struct sockaddr_in *arg) {
   struct hostent *hp;
   printf("  sockaddr_in: ");
   printf("Domain=%d, ", arg->sin_family);
   hp=gethostbyaddr((const char *)&(arg->sin_addr), sizeof(arg->sin_addr), 
                      AF_INET);
   printf("Hostname=%s, ", hp->h_name);
   printf("Port=%d, ", ntohs(arg->sin_port));
   printf("Address=%s,\n", inet_ntoa(arg->sin_addr));
}    

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);
}

help_msg()
{
   printf("format: ist2r -[df]\n");
   printf("        option: d set debug mode\n");
   printf("        option: f set fork processing mode\n");
}

void 
doit(int msgsock) {
   char buf[1024];
   char fromBuf[1024];
   int i, rval;
   do {
      if ((rval = read(msgsock, buf, 1024)) < 0)
         perror("reading stream message");
      i = 0;
      if (rval == 0) {
         printf("Ending connection\n");
         break;
      } else
         buf[rval] = '\0';
         printf("rcvd msg-->%s\n", buf);
         printf("What is your reply (\"$\" to break connection)?");
         if ((rval=getline(fromBuf, 1024)) <= 0) 
            break; 
         if (fromBuf[0] == '$') {
            rval = 0;
            break;
         }
         /* send back reply */
         if (write(msgsock, fromBuf, strlen(fromBuf)) < 0)
            perror("writing on stream socket");
      } 
      while (rval != 0);
}
 
main(argc, argv)
int argc;
char *argv[];
{ 
   int sock;
   int length;
   struct sockaddr_in server;
   struct sockaddr_in from;
   int msgsock;
   int debug = 0;
   int forkflag = 1;
   extern char *optarg;
   extern int   optind;
   int option_exist = 0;
   int c;

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

      case 'f':
         forkflag = 1;
         printf("turn on fork processing mode.\n");
         break;
      case '?':
         help_msg();
         exit (1);
      default:
         fprintf (stderr, "unrecognized arg >%s<\n", optarg);
         help_msg();
         exit (1);
      }
   }               

   /* create socket from which to read */
   sock = socket(AF_INET, SOCK_STREAM, 0);
   if (sock < 0) {
      perror("opening stream socket");
      exit(1);
   }
   /* create name structure with wildcard using INADDR_ANY */

   server.sin_family = AF_INET;
   server.sin_addr.s_addr = INADDR_ANY;
   server.sin_port = 0;  

   /* port no. < 1024 IPPORT_RESERVED is for privillege process */
   /* here just initialized it, it will be assigned value after call */
   /* getsockname() */

   if (bind(sock, &server, sizeof(server))) {
      perror("binding server to datagram socket");
      exit(1);
   }
   /* Find assigned port value and print out. */
   printf("before getsockname socket has port #%d\n", ntohs(server.sin_port));
   length = sizeof(server);
   if (getsockname(sock, &server, &length)) {
      perror("getting socket name");
      exit(1);
   }
   printf("socket has port #%d\n", ntohs(server.sin_port));

   /* start accepting connections */
   listen(sock, 1);
   do {
      msgsock = accept(sock, (struct sockaddr *)&from, &length);
      if (debug)  {
          printf("accept request from \n");
          printsockaddr(&from);
      }            
      if (msgsock == -1) { perror("accept"); exit(2);}
      if (forkflag) {
         if (fork()==0) {
            close(sock);
            doit(msgsock);
            exit(0);
         } 
      } else {
         doit(msgsock);
      }
      close(msgsock);
   } 
   while (TRUE);
}