tinyFTP

Implementation of a tiny FTP client and server

Introduction to tinyFTP

I spent 21 days to finish this project from Aug 3 to Aug 24, 2015 , and very happy to share with you. You can fork from my Github repository tinyFTP. Also, you can pull requests if you have any questions. I will continue updating this interesting project, and start to spend some time to finish a more interesting project tinyHttpd, a tiny web server just for fun.

PDF Online: tinyFTP_en tinyFTP_zh

PDF Download: tinyFTP_en tinyFTP_zh

Platform

Ubuntu14.04 64bit

Basics

Commands

ftp [ip-address]

• GET: get [remote-file] [local-file]
• PUT: put [local-file] [remote-file]
• RGET: get [remote-dir] [local-dir]
• RPUT: put [local-dir] [remote-dir]
• LS: ls [remote-dir] local: LLS
• CD: cd [DIR] local: LCD
• RM: rm [remote-file] local: LRM
• PWD: pwd [-a] local: LPWD
• MKDIR: mkdir [remote-dir] local: LMKDIR
• RMDIR: rmdir [remote-dir]
• SHELL: shell [shell-cmd-string] local: LSHELL
• USERADD: useradd -u [username] -p [password]
• USERDEL: userdel [username]
• QUIT: quit
• HELP: help [command]

Special attention

1. anonymous user can only GET a file, but not PUT, MKDIR, RM, RMDIR, or shell.
2. admin user has permission to do USERADD and USERDEL command.

Features

• Multithread concurrency Model for server
• User authentication
• Salting password
• User space isolation
• Breakpoint resume
• Flash transmission

FTP model

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

                Server-FTP                   Client-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

In the model described in Figure 1, the user-protocol interpreter initiates the control connection. The control connection follows the Telnet protocol. At the initiation of the user, standard FTP commands are generated by the user-PI and transmitted to the server process via the control connection. (The user may establish a direct control connection to the server-FTP, from a TAC terminal for example, and generate standard FTP commands independently, bypassing the user-FTP process.) Standard replies are sent from the server-PI to the user-PI over the control connection in response to the commands.

The FTP commands specify the parameters for the data connection (data port, transfer mode, representation type, and structure) and the nature of file system operation (store, retrieve, append, delete, etc.). The user-DTP or its designate should "listen" on the specified data port, and the server initiate the data connection and data transfer in accordance with the specified parameters.

TODO

1. Breakpoint resume for GET command.
2. Enhance admin's permission to do more management.
3. Reactor concurrency Model for server: epoll implementation.
4. Deamon server.
5. syslogd: format log messages.
6. DEBUG macro for easy debugging.
7. Robust error handling, especially for internet exception.
8. More elegant class design, make full use of powerful features of C++.