client.c

#include"util.h"
  
void * recvMessage(void * socket) 
{
  int sockfd, returnRecvfrom;
  char buffer[MAX]; 
  sockfd = (int) socket;

  while(1) 
  {
  //fill with zero
    memset(buffer, 0, MAX);  
    returnRecvfrom = recvfrom(sockfd, buffer, MAX, 0, NULL, NULL);
      if(returnRecvfrom< 0)
      {
          perror("Error recvfrom");
      } 
      else
      {
          printf("server: ");

          //fput means string  put
          fputs(buffer, stdout);  
          //strncmp for use string compare
            if((strncmp(buffer,"bye",3))==0)
            {
              printf("Client Exit...\n");
              break;  
           }
        }
    }
}

int main(int argc, char *argv[])
{ 
  int sockfd, returnStatus ,simplePort ,returnThread,returnSendto;  
  char buffer[MAX];
  struct sockaddr_in addr ;
  pthread_t rThread;

  if (argc != 3)
  {
    fprintf(stderr, "Usage : <port>  <ip address> \n" ,argv[0]);
    exit(1);
  }

  //creating socket for client
  sockfd = socket(AF_INET, SOCK_STREAM, 0);  

  if (sockfd < 0) 
  {
    fprintf(stderr, "Could not create a socket!");
    exit(1);
  }
  else
  {
    printf("Socket created !\n");
  }

  //fill with zero
  memset(&addr, 0, sizeof(addr)); 

  // atoi converts from string to integer  
  simplePort=atoi(argv[1]); 

  //aderss family IPv4 Internet protocols
  addr.sin_family = AF_INET; 

  //inet_addr,function that makes it easy to convert strings into IP addresses that are compatible with the sockaddr structure
  inet_addr(argv[2], &addr.sin_addr.s_addr);
  
  //hton will convert integers from local host’s native byte order to network byte order 
  addr.sin_port = htons(simplePort);     

  returnStatus = connect(sockfd, (struct sockaddr *) &addr, sizeof(addr)); 

  //If successful, connect() returns 0 ,otherwise, –1 is returned
  if (returnStatus == 0) 
  {
      fprintf(stderr, "Connect successful!\n");
  }
  else
  {
      fprintf(stderr, "Could not connect to address!\n");
      close(sockfd);
      exit(1);
  }
  
  //fill with zero
  memset(buffer, 0, MAX);
  printf("Enter your messages!\n");

  //creating a new thread for receive messages from  server
  returnThread = pthread_create(&rThread, NULL, recvMessage, (void *) sockfd);
  if (returnThread) 
  {
      printf("ERROR: %d\n", returnThread);
      exit(1);
  }

  //fgets() ,Reads the character of the string type
  while (fgets(buffer, MAX, stdin) != NULL) 
  {
    returnSendto = sendto(sockfd, buffer, MAX, 0, (struct sockaddr *) &addr, sizeof(addr));  
        if (returnSendto < 0)
        {  
            printf("Error sending data!\n\t-%s", buffer);  
        }
  }

  //close() function to close socket
  close(sockfd);
  
  pthread_exit(NULL);

  return 0;    
}