/*****************************************************************************
 *** Demo program explaining the client-server model                       ***
 *** This is the client program                                            ***
 *** Written by Abhijit Das, CSE, IIT Kharagpur                            ***
 *** Last modified: October 13, 2006                                       ***
 *****************************************************************************/

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

/* Global constants */
#define SERVICE_PORT 41041
#define MAX_LEN 1024
#define DEFAULT_SERVER "10.5.17.128"

/* Function prototypes */
int serverConnect ( char * );
void serverTalk ( int );

/* Connect with the server: socket() and connect() */
int serverConnect ( char *sip )
{
   int cfd;
   struct sockaddr_in saddr;   /* address of server */
   int status;

   /* request for a socket descriptor */
   cfd = socket(AF_INET, SOCK_STREAM, 0);
   if (cfd == -1) {
      fprintf(stderr, "*** Client error: unable to get socket descriptor\n");
      exit(1);
   }

   /* set server address */
   saddr.sin_family = AF_INET;              /* Default value for most applications */
   saddr.sin_port = htons(SERVICE_PORT);    /* Service port in network byte order */
   saddr.sin_addr.s_addr = inet_addr(sip);  /* Convert server's IP to short int */
   bzero(&(saddr.sin_zero),8);              /* zero the rest of the structure */

   /* set up connection with the server */
   status = connect(cfd, (struct sockaddr *)&saddr, sizeof(struct sockaddr));
   if (status == -1) {
      fprintf(stderr, "*** Client error: unable to connect to server\n");
      exit(1);
   }

   fprintf(stderr, "Connected to server\n");

   return cfd;
}

/* Interaction with the server */
void serverTalk ( int cfd )
{
   char buffer[MAX_LEN];
   int nbytes, status;

   /* receive greetings from server */
   nbytes = recv(cfd, buffer, MAX_LEN-1, 0);
   if (nbytes == -1) {
      fprintf(stderr, "*** Client error: unable to receive\n");
      return;
   }
   buffer[nbytes] = '\0';
   printf("%s",buffer);
   fflush(stdout);

   /* read string from user */
   fgets(buffer, MAX_LEN, stdin);
   buffer[strlen(buffer)-1] = '\0';

   /* send the user's response to the server */
   status = send(cfd, buffer, strlen(buffer), 0);
   if (status == -1) {
      fprintf(stderr, "*** Client error: unable to send\n");
      return;
   }

   /* receive server's processing results on the string */
   nbytes = recv(cfd, buffer, MAX_LEN-1, 0);
   if (nbytes == -1) {
      fprintf(stderr, "*** Client error: unable to receive\n");
      return;
   }
   buffer[nbytes] = '\0';
   printf("%s",buffer);
   fflush(stdout);
}

int main ( int argc, char *argv[] )
{
   char sip[16];
   int cfd;

   strcpy(sip, (argc==2) ? argv[1] : DEFAULT_SERVER);
   cfd = serverConnect(sip);
   serverTalk(cfd);
   close(cfd);
}

/*** End of client.c ***/