text: /* 
   * File:  dataStructure.h
   * Purpose: common data structures
   */
  
  #define PKTLen 1440
  
  struct Packet{
      int seq_num;
      short pktsize;
      char data[PKTLen];
  };
  
  struct AckMessage{
      int ack_num;
  };
  
  struct PacketSendTime{
      int seq_num;
      struct timeval tv;
  };
  