CS 349 - Assignment 3

Authors:- 
Rohit Rangan
11012333

Siddharth Ancha
11010175

-------------------------------------------------------------------------------
PROJECT DESIGN
-------------------------------------------------------------------------------


                                          -------------
                                          |/---------\|
                                          ||   User  ||    --------
                                          ||Interface|<--->| User |
                                          |\----^----/|    --------
                ----------                |     |     |
                |/------\|  FTP Commands  |/----V----\|
                ||Server|<---------------->|   User  ||
                ||  PI  ||   FTP Replies  ||    PI   ||
                |\--^---/|                |\----^----/|
                |   |    |                |     |     |
    --------    |/--V---\|      Data      |/----V----\|    --------
    | File |<--->|Server|<---------------->|  User   |<--->| File |
    |System|    || DTP  ||   Connection   ||   DTP   ||    |System|
    --------    |\------/|                |\---------/|    --------
                ----------                -------------

                Server-FTP                   USER-FTP

    NOTES: 1. The data connection may be used in either direction.
           2. The data connection need not exist all of the time.

                    Figure 1  Model for FTP Use

-------------
Server Design
-------------

We need the server to support multiple connections at a time. To support this,
we process each new client connection in a separate thread. We process both the
data and the control connections for a particular user in a single thread, i.e.
once a data connection is initialized, no control packets can be sent. We close
the data connection on completion of the transfer. Once the client issues a
quit command, we close the control connection, thereby terminating all
communications.

-------------
Client Design
-------------

The client connects to the advertised port of the server. After establishing
the connection, the client starts an interactive shell. This shell processes
input from the user and sends a request to the server. We print the server's
response to the terminal and store/send a file from/to the server. Once the
user types the quit command, we close the connection to the server and exit.

---------------
Project Modules
---------------

We have the following modules:-

1. Client Module - Contains the main code for the client. This module's only
                   function is to send/receive messages to/from the server and
                   call functions to process the messages received from the
                   server. The module also contains an interactive shell which
                   processes user input and transforms them into messages for
                   the client to send.

2. Message Module - Contains fucntions to interpret messages from the server
                    as well as the client. Also contains functions to package
                    messages from the server and the client.

3. Server Module - Contains the main code for the server. This module's only
                   function is to send/receive messages to/from the client(s)
                   and call functions to process the messages.

------------------
Module Interaction
------------------

Client Side
-----------


          Sending messages
          for communication
          with the server.
        --------     ---------
        |Client|<--->|Message|
        |Module|     |Module |
        --------     ---------
            ^           ^
             \         /
    Starting  \       / Processing commands
    the module \     / and creating messages
    to process  \   / in reply to those.
    data.        \ /
                  V
            -------------
            |Interactive|
            |   Shell   |
            -------------

    Figure 2  Client side module interaction



Server Side
-----------


              Sending messages
              for communication
              with the client.
            --------     ---------
            |Server|<--->|Message|
            |Module|     |Module |
            --------     ---------

    Figure 3  Server side module interaction


(Interaction between the client and the server in shown in Figure 1)


-------------------------------------------------------------------------------
PROJECT DIRECTORY STRUCTURE
-------------------------------------------------------------------------------

--{root}                    - The assignment's root directory.
  +--Makefile               - The Makefile for compiling the code.
  +--README                 - This file!
  +--include/               - Contains the header files.
  |  +--client.h            - Client header file.
  |  +--request.h           - FTP client request header file.
  |  +--response.h          - FTP server response header file.
  |  +--return_code.h       - FTP server return codes.
  |  +--server.h            - Server header file.
  |  +--socket.h            - Wrapper for UNIX socket implementation.
  +--src/                   - Contains the source code.
  |  +--client.cpp          - Client source code.
  |  +--client_main.cpp     - Client main function.
  |  +--request.cpp         - FTP client request implementation.
  |  +--response.cpp        - FTP server response implementation.
  |  +--server.cpp          - Server source code.
  |  +--server_main.cpp     - Server main code.
  |  +--socket.cpp          - UNIX socket implemented as a class.

-------------------------------------------------------------------------------
REQUIREMENTS
-------------------------------------------------------------------------------

1. GCC or clang (To compile the C++ code).

2. GNU Make.

-------------------------------------------------------------------------------
INSTRUCTIONS TO COMPILE
-------------------------------------------------------------------------------

1. At the root directory (the directory containing this README), execute the
   "make" command.

2. After make finishes executing, the executables will be named - client and
   server, for the client and the server respectively.

-------------------------------------------------------------------------------
INSTRUCTIONS TO RUN THE CODE
-------------------------------------------------------------------------------

1. To run the server, execute "./server PORT_NUMBER" if the server program is
   in the current directory.
   PORT_NUMBER is the port which the server listens to, for any incoming
   connections. It must be positive and less than 65535.

   To terminate the server gracefully, give the input "CTRL + C". It will then
   initiate server shutdown as indicated in the sample output of the server.

2. To run the client, execute "./client HOST_NAME PORT" if the client program
   is in the current directory.
   HOST_NAME is the URL or the IP Address of the server we connect to.
   PORT specifies the listen port of the server.

-------------------------------------------------------------------------------
SAMPLE OUTPUT - SERVER
-------------------------------------------------------------------------------

RangansMacBookPro:FTP-Client-Server rohitrangan$ ./server 1221
Server Initialized!

Accepted connection from - 127.0.0.1:53630

^C
Initiating Server Shutdown...
Closing All Connections... Success!

All Connections Closed. Exiting...


-------------------------------------------------------------------------------
SAMPLE OUTPUT - CLIENT
-------------------------------------------------------------------------------

RangansMacBookPro:FTP-Client-Server rohitrangan$ ./client 127.0.0.1 1221
220 FTP-Server
ftp> pwd
250 /Users/rohitrangan/Workspace/FTP-Client-Server
ftp> ls
200 Connection Success
150 Sending Directory Information

Makefile
README
client
include
server
src

226 Success
ftp> cd /Users/rohitrangan/Workspace/FTP-Client-Server/src
250 Changed Directory
ftp> pwd
250 /Users/rohitrangan/Workspace/FTP-Client-Server/src
ftp> !pwd 
/Users/rohitrangan/Workspace/FTP-Client-Server
ftp> get client.cpp
200 Connection Success
125 Sending file
226 File send success
ftp> !ls
Makefile
README
client
client.cpp
include
server
src
ftp> quit
221 Terminating


-------------------------------------------------------------------------------
NOTE
-------------------------------------------------------------------------------

1. All terminal commands are given in quotes

2. The code was written and tested on MacOSX 10.7.5 and compiled with
   clang-425.0.28

-------------------------------------------------------------------------------