Librecast Multicast Sync Tool (lcsync)

Work in progress.

Librecast file and data syncing tool.

Compare data with merkle trees, sync via multicast.

File Syncing

Data is compared by generating a merkle tree using blake2s hashes.

For local file syncing we walk the trees and compare the hashes to find which data blocks are different.

When sending across a network, the source (sender) chooses how many multicast groups (channels) to use as a power of 2 and divides the data chunks to send according to the matching level of the merkle tree, sending data for that portion of the tree on a channel created from the appropriate node hash.

The merkle tree data is also sent on a loop on the channel which matches the root hash of the file. NB: if only one data channel is in use, this is going to conflict, so we hash in an extra flag to mark it as tree data when forming the channel hash.

Usage

Syncing local files:

`lcsync source destination`

lcsync assumes source and destination are network addresses unless told otherwise. To refer to a local destination, you must specify the path. For files in the local directory, prefix them with ./

Fetch remote file, save as localfile in current directory:

`lcsync remote ./localfile`

Serve local file:

`lcsync /path/to/localfile`

Serve local file "./somefile" as alias "easy2type":

`lcsync ./somefile easy2type`

and fetch that file:

`lcsync easy2type`

Testing

`sudo make net-setup` (`sudo make net-teardown` when finished)

`sudo ip netns exec vnet0 sudo -u `id -un` /bin/bash`

Now we can run `make test` and `sudo make cap` in our test namespace.

License

GPLv3+