[Communication protocol proposal. Not yet fully implemented and still expected to change.]

Nodes communicate by exchanging messages through network sockets. Basic message format is simple:

		json-length: ABC

		bin-length: DEF

		{... JSON payload ...}

		... binary payload ...

`ABC` is the JSON payload length (decimal integer), `DEF` is the binary payload length. JSON payload always contains a "command" field.

The client sends a request (a message) and the server answers with a response (another message).

## Commands ##

### <a name="init"></a>init ###

Initiates communication between the client and the server. Checks that the nodes can meaningfully talk to each other.

#### Params ####

- [(int) major, (int) minor, (int) tiny] version version: program version. Both the client and the server are to check for compatibility with their partner.

- {push, pull} action: what the client desires to do

- (str) filename: name of the file to be synchronized

- (int) blockSize

- (int) blockCount

#### Responses ####

- [init](#r-init)

- [deny](#deny)

### <a name="req"></a>req ###

Requests hashes or a data chunk from the server.

#### Params ####

- {hash, data} dataType

hash

- [(int) i0, ...] index: list of requested node keys from the HashTree

data

#### Responses ####

- [send](#send)

- [err](#err)

### <a name="send"></a>send ####

Sends data. Can be a client action or a response to a request.

#### Params ####

- {hash, data} dataType

- index: see [req](#req)

#### Responses ####

- [ack](#ack)

- [err](#err)

### <a name="end"></a>end ###

Cease talking and close the connection.

#### Params ####

- {push} (optional) action: unlocks the server's dirty lock

#### Responses ####

- end

## Responses ##

### <a name="r-init"></a>init ###

See [the init command](#init). If the client doesn't like server's protocol version, it is free to [end](#end) the connection.

#### Params ####

- [(int) major, (int) minor, (int) tiny] version

### <a name="deny"></a>deny ###

The server refuses connection. It might be busy, corrupted or incompatible.

#### Params ####

- (int) retry: suggested delay in seconds before another attempt at connection

- (int) status

- (str) msg

### <a name="ack"></a>ack ###

Everything is alright, but the server has nothing better to say.

#!/bin/bash

# setup encrypted container

#sudo losetup -f ext2.img

#sudo cryptsetup open --type=luks /dev/loop0 ext2luks

#sudo mkfs.ext2 /dev/mapper/ext2luks

# generate certificate

# openssl req -x509 -newkey rsa:4096 -keyout key.pem -out cert.pem -days 365 -nodes -subj "/CN=name"

set -e

DIRNAME=`dirname $0`

sudo losetup -f ~/ext2.img

sudo cryptsetup open --type=luks /dev/loop0 ext2luks

sudo mount /dev/mapper/ext2luks ~/temp

sudo rdiff-backup -v 5 ~/Dokumenty ~/temp/Dokumenty

sudo rdiff-backup -v 5 ~/Obrázky ~/temp/Obrázky

sudo umount /dev/mapper/ext2luks

sudo cryptsetup close ext2luks

sudo losetup -d /dev/loop0

echo

python $DIRNAME/morevna.py build ~/ext2.bin ~/ext2.img

python $DIRNAME/morevna.py push --tree ~/ext2.bin ~/ext2.img

import json

import stats

class NetworkReader:

	def __init__(self,stream):

		self._stream=stream

	def readMsg(self):

		data=self._stream.readline()

		assert data

		stats.logReceived(data)

		jsonLength=int(data.split(b":")[1].strip()) # "json-length: length" -> length

		data=self._stream.readline()

		assert data

		stats.logReceived(data)

		binLength=int(data.split(b":")[1].strip()) # "bin-length: length" -> length

		jsonData=self._stream.read(jsonLength)

		assert len(jsonData)==jsonLength

		stats.logReceived(jsonData)

		jsonData=json.loads(str(jsonData,encoding="utf-8"))

		binData=self._stream.read(binLength)

		assert len(binData)==binLength

		stats.logReceived(binData)

		return (jsonData,binData)

class NetworkWriter:

	def __init__(self,stream):

		self._stream=stream

	def writeMsg(self,*args):

		msg=self.prepMsg(*args)

		self._stream.write(msg)

		self._stream.flush()

		stats.logSent(msg)

	def prepMsg(self,jsonData,binData=b""):

		jsonLength=bytes("json-length: "+str(len(jsonData))+"\n",encoding="utf-8")

		binLength=bytes("bin-length: "+str(len(binData))+"\n",encoding="utf-8")

		return b"".join((jsonLength,binLength,jsonData,binData))