/* unixCient.c - Example code of UDP client */  /* Copyright 1984-1997 Wind River Systems, Inc. */  /* modification history -------------------- 01c,06nov97,mm   added copyright. 01b,24Sep97,mm   cast arg 5 of sendto and recvfrom    01a,10Feb94,ms   cleaned up for VxDemo. */   /***********************************************************************  * DESCRIPTION  *     Code to be executed by client. Writes request/message nto socket  *     and optionally receives a reply back. Code executes on UNIX,  *     therefore UNIX header files are included.  *  *   * EXAMPLE  *     On the UNIX host:  *     % unixClient   *  */ 	  /* Code to be executed by client. Writes request/message  * into socket and optionally receives a reply back.  */  	  /* Code executes on UNIX therefore include UNIX header files. */  #include <stdio.h> #include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include "udpExample.h" #include "client.h"   main()      {     int sFd;				/* Socket file descriptor */     int mlen;				/* Length of message to send */     struct request myRequest;		/* Request/Message to send to server */     struct sockaddr_in replyAddr;	/* If expecting reply,  					 * address of node that sent 					 * the reply */     char reply;				/* TRUE if want reply */     char replyBuf[REPLY_MSG_SIZE];	/* Buffer to store reply 					 * from server. */     struct sockaddr_in serverSockAddr; /* Address of server */      /* Size of socket address structure */     int sockAddrSize = sizeof (struct sockaddr_in);      /* Create socket */     if ((sFd = socket (AF_INET, SOCK_DGRAM, 0)) == ERROR)         { 	fprintf (stderr, "Error creating socket\n"); 	return (ERROR); 	}      /* Bind not required - port number will be dynamic */     /* Build server socket address */     bzero (&serverSockAddr, sockAddrSize);     serverSockAddr.sin_family = AF_INET;     serverSockAddr.sin_port = htons (SERVER_PORT_NUM);     serverSockAddr.sin_addr.s_addr = inet_addr (SERVER_INET_ADDR);      /* Build request/message , prompting user */     printf ("Message to send: \n");     mlen = read (STDIN_FILENO, myRequest.message, MSG_SIZE);     myRequest.message[mlen - 1] = '\0';      printf ("Would you like a reply (Y or N): \n");     scanf ("%c",&reply);      switch (reply)         { 	case 'y': 	case 'Y': myRequest.reply = TRUE;  	    break;  	default: myRequest.reply = FALSE;             break; 	}      /* Send message/request to server */     if (sendto (sFd, (caddr_t) &myRequest, sizeof (myRequest), 0,                   (struct sockaddr  *) &serverSockAddr,sockAddrSize) == ERROR)         { 	perror ("sendto"); 	close (sFd); 	return (ERROR); 	}      /* If expecting reply, read and print it */     if (myRequest.reply)         { 	/* Should use select here. If request or reply get lost,   	 * this code will block forever. */          if (recvfrom (sFd, replyBuf, REPLY_MSG_SIZE, 0,             (struct sockaddr  *) &replyAddr, &sockAddrSize) == ERROR)             { 	    perror ("recvfrom"); 	    close (sFd); 	    return (ERROR); 	    }          printf ("MESSAGE FROM SERVER:\n%s\n", replyBuf);         }      close (sFd);      }