Computer Science 360
                             Assignment 2
                         Due 11:59 PM Feburary 4

Develop a program called udping that can function as either a udp ping
server (which simply echoes udp ping packets back to there source) or
as a ping client which works similarly to the standard ping program.

The program must support the following command line options:
                                                                  Default
                                                                  Value
 -c ping-packet-count  (stop after sending this many)            0x7fffffff
 -i ping-interval      (interval in seconds between ping sends)  1.0
 -p port number        (the port number the server is using)     33333
 -s size in bytes      (of the application data sent)            16
 -n no_print           (only print summary stats)                print all
 -S Server             (operate in server mode)                  client mode

The last command line parameter is the host name of where the server
is running.

Example:
   udping -S -p 50000      (starts the server and binds it to port 5000)
   udping -i 0.1 -c 100 -s 200 -p 50000 jmw  (send 100 pings of size 200
                                              bytes at a rate of 10 pings
                                              per second to a server running
                                              on host jmw)

Example output:
  notes (1) command line options should be echoed to the stderr
        (2) other output data should go to the stdout
        (3) in the default mode one line should be printed for
            every ping RECEIVED BY THE CLIENT (The server should
            not print anything).  The line should contain

              The sequence number carried by the ping packet
              The number of bytes of application data
              The round trip time in milliseconds in the format shown
        (4) The statistics lines should be printed after the number
            of pings specified have been sent or the user terminates
            the client with a Ctrl-C

acad/cs360/examples ==> ./udping -c 10  -s 300 -i 0.1  -p 33333 jmw
Count        10
Size        300     /___________________ Goes to stderr
Interval  0.100     \
Port      33333
       1      300      0.104
       2      300      0.035
       3      300      0.027
       4      300      0.035
       5      300      0.025   /___________________ Goes to stdout
       6      300      0.026   \                      |
       7      300      0.025                          |
       8      300      0.050                          |
       9      300      0.025                          |
      10      300      0.025                          V
10 packets transmitted, 10 received, 0%  packet loss, time 1004 ms
rtt min/avg/max = 0.025/0.038/0.104 msec

If the -n option is used then printing of individual responses should
be suppresed.

acad/cs360/examples ==> ./udping -c 100 -s 300 -i 0.01   -n  jmw
Count       100
Size        300
Interval  0.010
No print
100 packets transmitted, 100 received, 0%  packet loss, time 1003 ms
rtt min/avg/max = 0.016/0.026/0.108 msec

Implementation requirements:

(0) Use the getopt() function to parse the command line arguments
(1) When operating in client mode, the program MUST create two child
    threads.  One thread will send pings and the other will receive
    them.  In server mode NO THREADS should be created.
(2) The sender() thread MUST use the pthread_cond_timedwait() function
    to wait until it is time to send the next ping.  The proper time
    to send is:  start_time + (seq# - 1) x ping-interval
(3) The receiver thread MUST compute the round trip time of the ping,
    the number of pings received, the min, max, and sum of the round
    trip times.
(4) Round trip times must be computed to (nominally) microsecond
    level accuracy using the gettimeofday() function.
(5) The signal() function must be used to set up handler that
    will print the statistics lines and the exit(0) if the user
    enters CTRL-C.