QFTP

A prototype FTP server. Minimally featured, but supports several basic FTP commands. See router.clj for a list.

Installation & Usage

IMPORTANT: The server will not run unless it can create a "files" folder in the JVM's working directory to act as the FTP server's file root.
DO NOT run it in a directory if there's a 'files' folder with important files.

1. Download the uberjar from here and run

    java -jar qftp-0.1.0-standalone.jar
   

   You may need to set permissions on the jar or run as sudo. The server will exit if it can't create the files folder.

2. Download the code from the Github repo.

    lein run
   

To connect to the server, you can use the FTP commands on most systems. This client mimics a Telnet terminal for commands. See Simple Session down below for an example.

Documentation

Marginalia documentation is available here.

Connect with your favorite FTP client. PASV mode not supported, and don't forget to set binary mode for non-ASCII transfers!

FSM

The commands that the server accepts are defined in the router. They're validated by an Automat compiled finite state machine. The one in place is simple, but can be easily extended to enforce more complex server logic.

Bugs

• The max filesize that can be transferred is 20-50 kb.
• The server is programmed to be async, but a suspected bug in the async.sockets library is causing it to not process new connections.
• You must force-quit the server in order to stop it.
• Using "../" to indicate "going up a folder" in a path works but results in strange working-directory paths on the server.

Wishlist

1. Daemonizing the FTP service
2. Running the app from within a REPL (allowing for live app editing)
3. CIDER support and other nice Clojure "features"
4. Zach Tellman's "Manifold" library looked like a more elegant way to handle communication across sockets. With more time, I would've investigated this option more.
5. Pull the response codes out of each response and replace them with keyword :response-code. The response code would be inserted into the message.
6. Make the "session" map into a record
7. Refactor FTPL system to be macro based
8. Refactor qftp.file-system code to use Java Path class for more robust file-system handling
9. Refactor the "how side-effects are invoked" to be entirely separate from the FTP logic that decides WHICH side-effects to be invoked. The FTP logic should return a "list of side effects" that is executed by a mechanism that guarantees they will be executed only one time. This allows for a nearly bullet-proof handling of connection state while still executing asynchronously.

Example Session

quest@QLAPTOP-UBU> ftp      
  ftp> open localhost
  Connected to localhost.
  220-Pure FTP Server (Development)
  220 A Clojure Implementation on top of Java Sockets
  Name (localhost:quest): quest
  331 Password required for quest
  Password:
  230 Logged On
  Remote system type is JVM.
  ftp> ls
  200 Port command successful
  150 Opening data channel for directory listing
  transferred
  226 Successfully transferred /
  ftp> cd transferred
  250 CWD successful. "/transferred" is current directory.
  ftp> ls
  200 Port command successful
  150 Opening data channel for directory listing
  favicon.png fawhogoo.txt example.txt Warframe.jpg launchy.db
  226 Successfully transferred /transferred
  ftp> get favicon.png
  local: favicon.png remote: favicon.png
  200 Port command successful
  150 Opening data channel for file download from server of /transferred/favicon.png
  WARNING! 6 bare linefeeds received in ASCII mode
  File may not have transferred correctly.
  226 Successfully transferred favicon.png
  880 bytes received in 0.00 secs (356.2915 kB/s)
  ftp> binary
  200 Type set to I
  ftp> get favicon.png
  local: favicon.png remote: favicon.png
  200 Port command successful
  150 Opening data channel for file download from server of /transferred/favicon.png
  226 Successfully transferred favicon.png
  880 bytes received in 0.00 secs (768.6718 kB/s)
  ftp> ascii
  200 Type set to A
  ftp> get example.txt
  local: example.txt remote: example.txt
  200 Port command successful
  150 Opening data channel for file download from server of /transferred/example.txt
  226 Successfully transferred example.txt
  8 bytes received in 0.00 secs (4.8018 kB/s)
  ftp> put example.txt
  150 Opening data channel for file upload to server of example.txt
  226 Successfully transferred simple.txt
  8 bytes sent in 0.00 secs (4.8018 kB/s)
  ftp> bye
  221 Goodbye quest!         
quest@QLAPTOP-UBU > ls
favicon.png example.txt         

License

Copyright © 2016 Quest Yarbrough

Distributed under the MIT license.