FileTransport

Transfer files over TCP

Feature

Send file or folder
resume from break-point
update existing copy
GUI

How it works

client sends header

A folder is treated as multiple files in it.
To start, client sends the file header including structure as follows:

name_size	name	md5	compress	data_size
4 bytes	[name_size] bytes	16 bytes	1 byte	8 bytes

name_size indicates the length of the name that follows.
name is the UTF-8 encoded file name, with its relative path if sent in folder, it uses the same unix seperator in header and is connverted before sending and after receiving.
md5 is the calculated MD5 of the original file.
compress indicates weather the following data is compressed or not.
data_size is the size of data(compressed size if compress)

server feedback

On server side, it first read name_size, if 0 then the transfer process is over, else it reads all the header then sends shift back to client, which tells client the starting position of file and determines the length of data that follows.
Here's how shift is determined:

if [name].download exits and md5==[name].md5, then shift=[name].download
if [name] exits and its md5 is identical, then shift=0xffffffffffffffff
else shift=0

transfer

Once client receives shift, it will send data starting from shift.

Development

Python 3 is required.
Tested on both Linux and Windows.

alexhe101 / FileTransport