TCP/IP |  Assignment 2(ftp-client)  | Due according to syllabus
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The 2nd assignment is to use TCP from the client point of view,
and implement a simple FTP client.  RFCs 959 and 1123 are fundamental
references here.  The FTP client should operate as a shell.
It should be able to talk to any FTP server on the Internet, and
allow you to login either anonymously or as a user with a "shell" account.
We will call this application  "hbftp" for homebrew-ftp.

Fundamental references:

	1. Stevens TCP/IP Illustrated, Volume 1, Chapter 27.
	2. http://www.cs.pdx.edu/~jrb/tcpip/lectures/ftp/index.html
	3. RFCs 959/1123
	4. BSD ftp client in debug mode

The FTP client should have conceptually 3 parts,  TCP connection
abilities including of course use of gethostbyname(3) for DNS lookup.
This consists of a TCP socket/connect/and i/o calls and DNS gethostbyname call.
In addition, we should have an FTP protocol handler that uses the FTP
protocol, and at the highest-level a shell that reads user input lines
and translates them into FTP protocol requests.

Architecture:

		FTP client-side user interface including invocation
		---------------------------------------
		FTP protocol mechanism
		-----------------------
		TCP socket calls

The user interface should be invoked as follows:

(shell) hbftp (no parameters)

It should login/connect to an ftp server as follows (using an (hbftp)
prompt:

(hbftp) connect <system name>  <user>  <login>  

This will cause a TCP connection and subsequent FTP-level login
to the remote account.  Note that this supports both anonymous-style
and user-style login.  If you do not have a user-account anywhere,
you can always pick an anonymous ftp site to login to (e.g.,
ftp.cs.pdx.edu).  
		
	anonymous ftp login:  user=ftp,  password=you@somewhere.edu

Other required hbftp commands are:

(hbftp) read remote-file 

	Transfer a file in BINARY mode from the remote site to 
		this (client) site.  This is essentially a FTP 
		RETR, although that is of course not all of it.

(hbftp) write remote-file

	Transfer a file in BINARY mode from the client to the
	server.

(hbftp) delete file

	delete a file on the server.

(hbftp) cd /pathname

	chdir on the server

(hbftp) lcd /pathname

	chdir on the client

(hbftp) list

	list files on the server.  This can be in any format
	you like.

(hbftp) exit

	quit the client.

optional:

(hbftp) ! <command>

	You can and should do this on unix systems.  If you
	see a ! as a verb, just pass the rest to system(3).  If
	you are WNT-based ... forget it, although maybe you can
	invoke "command.com" (no idea ...).

Turn in at class (see syllabus for due date):
	1. src listings 
	2. makefile
	3. script output 
		roughly show your test plan as captured
		with script (or printfs) via client side runs.
	4. architecture description
		describe in ENGLISH the overall implementation
		of your protocol. This is an important part
		and will be the first thing the instructor/grader
		reads. Be sure and justify your decisions.
		Explain both FTP architecture and local o.s. system
		calls used.
	5. test plan
		This should consist of a set of test cases 
		where you list each test, describe what it does, 
		and describe what results you expect.
		Your script output should reflect a run of
		your test plan.  You may put tests in the
		test plan, that you cannot execute. Justify
		them and clearly state that you cannot execute
		the test.

ALSO turn in all of the above via e-mail to the instructor or grader
as a shar listing.  You turn in two things. 1. printed version
at class. 2. email version using shar.  The shar email version will
be used for deciding lateness.