compsys725 - assignment 1 (SFTP)

Computer Networks and Distributed Applications

• All commands have been implemented.
• Runs on localhost.
• Developed and tested using Ubuntu 16.04

Instructions

Setup of server and client

1. Clone repo to preferred directory
2. Navigate to /assignment1/server and open a terminal
3. Run java serverTCP
4. Navgate to /assignment1/client and open a terminal
5. Run java clientTCP

Logging in

There are 4 accounts stored in the assignment1/server/res/userList.txt

username: aA
account: bB
password: cC

username: upi123
account: upi123
password: upi123

username: aa
account: bb
password: cc

username: admin
account: admin (not required)
password: admin (not required)

To log in, an existing account with the correct password is needed. However, admin is able to log in without an account or a password.

Directory Structure

• Server
  The server's default directory is assignment1/server.
  Files sent to the server by the client can be stored in either the default directory or whichever subdirectory within its default directory.
  Available subdirectories are assignment1/server/a and assignment1/server/b.
• Client
  The client's default directory is assignment1/client.
  Files retrieved by the client from the server will be stored in the user's directory.
  Available directories are assignment1/client/<username> (i.e assignment1/client/admin)

Commands

USER <username>

Checks whether username exists in the server records. Grants immediate log in for User admin.

• If user is admin:

$ USER admin
from server: !admin logged in

• If username provided is in the server's userList:

$ USER upi123
from server: +user id valid, send account and password

• If username provided is not in the server's userList:

$ USER upi000
from server: -invalid user id, try again

ACCT <account>

Checks if the account corresponds to the provided username (for non-admin users). If password has been provided, account corresponding to the username and password will be logged in without having to provide the password again.

• If account provided corresponds to the username provided and have yet to provide password

$ ACCT upi123
from server: +account valid, send password

• If account provided corresponds to the username provided and have password have been provided:

$ ACCT upi123
from server: !account ok. skip the password

• If account provided does not correspond to the username provided:

$ ACCT upi000
from server: -invalid account, try again

PASS <password>

Checks if the password corresponds to the provided account (for non-admin users). Password can also be provided before providing the account.

• If password corresponds to the username and the user has provided account:

$ PASS upi123
from server: !logged in

• If password corresponds to the username but the user has yet to provide the account:

$ PASS upi123
from server: +send account

• If password does not correspond to the username provided:

$ PASS upi000
from server: -wrong password, try again

TYPE {A|B|C}

Changes the type of transmission byte stream. By default, type is binary. Requires user to be logged in.

If {A} is provided by the client, the type will be changed to ASCII.
If {B} is provided by the client, the type will be changed to Binary (default).
If {C} is provided by the client, the type will be changed to Continuous.

• If user is logged in:

$ TYPE a
from server: +using Ascii mode

• If user is not logged in:

$ TYPE A
from server: -you are not logged in. please do so

LIST {F|V} <directory>

Lists all the files and folders in the specified . If directory is not specified, a list of the files and folders within the current directory is returned. Requires user to be logged in.

If {F} is provided by the client, the listing will only include the filenames.
If {V} is provided by the client, the listing will include the details relating to the file which are the filenames, last modified time/date, filesize in bytes and the owner of the file.

• If user did not specify a directory:

$ LIST f
from server: +
./
../
a/ 
server.java 
b/ 
serverTCP.class 
res/ 
cat.jpg 

$ LIST v
from server: +
./
../
a/                             22/08/2018 02:22           4096              syamira 
server.java                    22/08/2018 22:08          31392              syamira 
b/                             22/08/2018 20:31           4096              syamira 
serverTCP.class                22/08/2018 22:15          16267              syamira 
res/                           22/08/2018 18:33           4096              syamira 
cat.jpg                        22/08/2018 18:08         628817              syamira 

• If user spcified a directory:

$ LIST f a
from server: +
./
../
p3.jpg 
p1.jpg 
p0.jpg 
p2.jpg 

$ LIST v a
from server: +
./
../
p3.jpg                         21/08/2018 22:49           9122              syamira 
p1.jpg                         21/08/2018 07:04         186623              syamira 
p0.jpg                         21/08/2018 16:56         478525              syamira 
p2.jpg                         21/08/2018 16:47         628817              syamira 

• If user did not specify a valid/any listing format:

$ LIST g
from server: -invalid file listing format

CDIR <new-directory>

Changes the current working directory to the specified . If user is not logged in, their account and password will be needed before being able to change the directory. Directory can only be changed to the subdirectories within the default one. Requires user to be logged in.

• If user is logged in:

$ CDIR a
from server: !changed working directory to ~/a

• If user is not logged in:

$ CDIR a
from server: -you are not logged in. please do so

• If directory is invalid:

$ CDIR k
from server: -cant't connect to directory because it doesn't exist

KILL <filename>

Deletes the specified in the current directory if the file exists and is not protected. Requires user to be logged in.

• If file can be deleted:

$ KILL t1.txt
from server: +t1.txt deleted

• If file cannot be deleted because it doesn't exist:

$ KILL tp.txt
from server: -no such file exist in the directory

• If file cannot be deleted because it is protected/a subdirectory:

$ KILL a
from server: -file is protected

NAME <filename>

Renames specified if it exists in the current directory. If server sends a '+', user needs to reply with a TOBE . Requires user to be logged in.

• If file exists:

$ NAME t5.txt
from server: +File exists

• If file doesn't exists:

$ NAME dog.jpg
from server: -can't find dog.jpg

TOBE <filename>

Provides the server with the following the NAME command. Should only be provided when user has received a '+' from server after sending a NAME command.

$ TOBE t1.txt
from server: +t5.txt renamed to t1.txt

DONE

Disconnects the client from the server.

$ DONE
from server: +closing connection. bye

RETR <filename>

Retrieves the specified from the server if the file fits in the client's system and if the file is in the current directory (subdirectories are not allowed). If the server has replied with the size of the file requested, user needs to reply with a SEND command if they wish to proceed. Requires user to be logged in.

• If user tries to retrieve a cat.jpg from the server's current directory:

$ RETR cat.jpg
from server: 628817

• If user tries to retrieve a file that is not on the server's current directory

$ RETR caat.jpg
from server: -file doesn't exist

Client needs to send a SEND command to proceed with file transfer. The client will be asked (by the client side, not server) to enter a filename for the incoming file.

$ SEND
save file as: 

$ cat.jpg 
cat.jpg has been saved to /admin

STOR {NEW|OLD|APP} <filename>

Sends a file to the server's current directory with a specified {NEW|OLD|APP} mode. Requires user to be logged in.

If {NEW} is provided by the client, the server will create a new file if the file is yet to exist.
If {OLD} is provided by the client, the server will overwrite the existing file if it already exists in the current directory. If it does not exist, a new file will be created.
If {APP} is provided by the client, the server will append to the existing file if it already exists in the current directory. If it does not exist, a new file will be created.

Send a cat.jpg to the server: The client will be asked (by the client side, not server) to enter the filename of the file to be sent and the size of the file will be returned so that the user do not need to check for the file size manually for the following SIZE command.

$ STOR NEW cat.jpg
enter filename to be sent to the server: 

The client will print the file size to the console and it can be used for the following the SEND command sent to the server

$ cat.jpg
filesize : 628817
from server: +file does not exist, will create new file

The server returns the status of the file

$ SIZE 628817
from server: +ok, waiting for file
from server: +saved cat.jpg to server's current directory