FTU (FileTransferringUtility)

Send files through the Net !

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What is that ?

This application is like an FTP server, but overcomplicated and probably overengineered monstrosity. (basically a file server, but P2P).

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Why ?

Learning

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How does this work ?

In order to transfer one file on one computer to another - they need to establish a connection.

In order to establish a connection - there needs to be a 1) sender (server) (the owner of the file), waiting for connections, and a 2) receiver (client), who will try to connect to a sender (server). If the requirements are met - a client will connect to a server and the packet exchange will begin.

The server and the client needs to communicate with packets according to certain rules, given by a protocol.

The packet has its header and body. They are divided into several groups of use by headers, this way we can specify what kind of data is stored inside packet`s body and react accordingly.

Thus, with a connection and a way of communication, the sender will send some packets with necessary information about the file to the receiver that describe a filename, its size and a checksum. The client (receiver) will have the choice of accepting or rejecting the packet. If rejected - the connection will be closed and the program will exit. If accepted - the file will be transferred via packets.

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Usage

./FTU [FLAGS_HERE] or FTU [FLAGS_HERE]

Flags

• -sending (bool) - if true - creates a server (sender) (also need to provide a -sharefile flag in that case), if false - creates a client (receiver)
• -port (int) - specifies a port; if -sending == true - listens on that port, else - connects to given port
• addr (string) - specifies an address to connect to (used when -sending=false)
• -sharefile (string) - specifies path to a file you want to share (used in pair with -sending=true), if given a valid path - a server will offer to share this file to a client
• -downloadto (string) - specifies path to a folder where the client wants to store downloaded file

Examples

• ./FTU -sending=true -sharefile="/home/some_path_here/FILETOSHARE.zip" - creates a server that will share FILETOSHARE.zip on port 8080
• ./FTU -sending=true -sharefile="/home/some_path_here/FILETOSHARE.zip" - port=727 - same as before, but on port 727
• ./FTU -sending=false -downloadto="/home/some_path_here/Downloads/" -addr="192.168.1.104" - creates a client (receiver) that will try to connect to 192.168.1.104 (local device) on port 8080 and if successful - downloads a file to given path
• ./FTU -sending=false -downloadto="/home/some_path_here/Downloads/" -addr=145.125.53.212 -port=8888 - same as before, but will try to connect to 145.125.53.212 on port 8888

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Known issues|problems|lack of features|reasons why it`s bad

• VERY slow; somewhat FIXED - , now faster than before
• VERY expensive on resources; somewhat FIXED - , no more json manipulations, only raw bytes`s wizardry !
• If MAXFILEDATASIZE is bigger than appr. 1024 - the packets on the other end will not be unmarshalled due to error ??; FIXED - , unnecessary, wrong, deprecated, destroyed !!!
• Lack of proper error-handling; somewhat FIXED -
• Lack of information about the process of transferring (ETA, lost packets, etc.); FIXED -
• No way to verify if the transferred file is not corrupted; FIXED via checksum-
• No encryption; FIXED -
• Messy and hard to follow code && file structure; partially FIXED (protocol is looking fairly good rn) - [ X ]
• No way to stop the download/upload and resume it later or even during the next connection; FIXED -
• No tests; FIXED -

Good points

• It works.

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IMPORTANT NOTE

This is NOT intended to be a serious application. I'm learning and this is a product of my curiosity. If you're a beginner too, please don't try to find something useful in my code, I am not an expert.

Also, this utility only works if both the server and the client have a port-forwarding enabled and configured. Fortunatelly, locally it works without any port-forwarding.

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Inspired by croc

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License

MIT