Compare files over a TCP connection.
You run netdiff on two computers and give it a filename. One side acts as the
server and the other as the client so that a tcp connection can be established,
but other than that both programs go through the same steps.
Both sides compute the merkle tree of the file. Then, the root hash is sent over the network. When a received hash doesn't match what was sent, the child hashes are queued to be sent. This is repeated until every block difference has been detected.
The process is then repeated for each block with errors, this time with a block size of 1, to determine which bytes don't match.
This reduces the number of exchanged hashes when compared to hashing every block and linearly comparing them, but it requires the full merkle tree to be calculated before exchanges can begin.
Messages are exchanged in plaintext. I considered adding TLS, but I'm using it via an SSH tunnel for now.
There's no network resilience, so if something goes wrong the program stops. This is particularly problematic because the merkle tree isn't stored anywhere, and it takes a while to compute for large files.
I'm not sure what to output. For now, the program outputs the offset and hexadecimal value of every mismatching byte.
USAGE:
netdiff [FLAGS] [OPTIONS] [filename]
FLAGS:
-h, --help Prints help information
-V, --version Prints version information
-v, --verbose increase verbosity
OPTIONS:
-b, --block-size <BYTES> chunk size in bytes [default: 1048576]
-c, --client <ADDRESS:PORT> destination network address and port
-s, --server <ADDRESS:PORT> listening network address and port
ARGS:
<filename> The filename to compare
An example running with block size of one byte and two mismatches:
$ cat input.txt
abcdefghijklmnopqrstuvwxyz0123456789
$ cat input2.txt
abcdefgHijklmnopqrstuvwxyz012345_789
$ netdiff input.txt -s 127.0.0.1:4000 > /dev/null &
$ netdiff input2.txt -c 127.0.0.1:4000
7=[68]
32=[36]