Assignment 4
                    CS494-unp
                   revised: 9/19/99

Assigned: 9/9/99
Due: 9/24/99 6:00pm

Objective:  UDP server and TCP client/server

Points: 50

Description:
  Somewhere on the CS subnet there is a host which every 10 seconds
  broadcasts a UDP packet on port  18765.  The 8 bytes of binary data in
  the packet look like the following

  struct Invitation {
	  unsigned int key;
	  unsigned short port; 
	  char pad[2];
  }

  All fields are in network byte order. The 32-bit "key" field and
  16-bit "port" field are only valid for the next 10 seconds.
  Within these 10 seconds, you must establish a TCP connection
  with the broadcast machine on the port designated by the "port"
  field.  You can get the IP address of the broadcast machine from
  data returned by  recvfrom().

  Once you've established the connection, you should send a 
  sizeof(struct Request) message
  over this TCP connection consisting of the following structure:

  struct Request {
	  unsigned int key;
	  unsigned short port;
	  char yourname[64];
  }

  The "yourname" field should be a null-terminated ASCII string of
  less than 64 characters holding your name and student ID.
  The "key" field should contain the key that you received from
  the UDP packet.  The "port" field should contain the TCP port number
  (in network byte order) of the port that YOUR process is
  listening on, so that the broadcast machine can connect to 
  you and send you a reply. (Note: you can statically assign your
  port and hope it's not in use, or use port 0 and let OS
  assign it, and then you can retrieve it after the bind() with
  getsockname()).

  The broadcast machine will attempt to establish a new TCP connection
  with your process on the port specified in your message and will
  send you the following 8-byte message (network byte order) over
  that TCP connection:

  struct Reply {
	  unsigned int result;
	  unsigned int receipt;
  }

  If the "result" field is non-zero then the key did not match
  or something else is messed up and you need to fix and try again.
  If the "result" field is zero, you are incredibly talented,
  and your program should print out the values of the "receipt" and "key"
  fields in hex (%x) and the IP address (w.x.y.z) AND name 
  of the broadcast machine.
  Submit these values along with your source files, makefile, using the script
  ~dunigan/cs494-unp/494submit

Do NOT use any of Stevens' libraries.
Do NOT write your own broadcast server for testing.
Your program will have to be running on a CS machine in order to receive
the broadcast datagram.  (Broadcasts do not leave subnets.)

Optional: Please indicate amount of time required to complete assignment.