darkriftpy 0.1.0

DarkriftPy is a Python implementation of DarkRift2

DarkRiftPy

DarkRiftPy is Darkrift2 written in Python 3. The implementation is fully compatible with the original version. So you can write a client side on Python that connects to a Darkrift2 server written in C# using the original Darkrift2 library, and vice versa.

DarkRiftPy is built on top of asyncio, Python's standard asynchronus I/O library, and provides a convenient high-level async/await API.

Installation

$ python3 -m pip install darkriftpy

Quick usage example

A simple exampls contains two separate scripts client.py and server.py for client and server respectively.

After client is connected to the server the latter waits for a darkrift message with tag 1, which contains a list of int32 integers in the payload. Once the message with tag 1 is received, the server starts to randomly select a value from the given list and sends it back to the client.

client.py:

import asyncio
import random


import darkriftpy


RND_POOL = 20

MIN_INT32 = (2 ** 31) * -1
MAX_INT32 = 2 ** 31 - 2


async def process_message(message: darkriftpy.DarkriftMessage) -> None:
    if message.tag != 2:
        raise ValueError("wrong message received")

    num = message.get_reader().read_int32()
    print(f"the server chose the number: {num}")


async def main() -> None:
    try:
        async with darkriftpy.connect("127.0.0.1", 4296, 4296) as client:
            items = [random.randint(MIN_INT32, MAX_INT32) for _ in range(RND_POOL)]

            writer = darkriftpy.DarkriftWriter()
            writer.write_int32s(items)

            await client.send(darkriftpy.DarkriftMessage(1, writer.bytes))

            async for message in client:
                await process_message(message)

            print("connection has been closed by the server")

    except ConnectionError:
        print("failed to connect to the server")


if __name__ == "__main__":
    asyncio.run(main())

server.py:

import asyncio
import random


import darkriftpy


async def handle_client(client: darkriftpy.DarkriftClient) -> None:
    message = await client.recv()

    if message.tag != 1:
        raise RuntimeError("wrong client message received")

        client.close()
        await client.wait_closed()
        return

    reader = message.get_reader()
    items = reader.read_int32s()

    while True:
        writer = darkriftpy.DarkriftWriter()
        writer.write_int32(random.choice(items))

        try:
            await client.send(darkriftpy.DarkriftMessage(2, writer.bytes))
        except darkriftpy.ConnectionClosedError:
            print(f"the client({client.connection_id}) has been disconnected")
            await client.wait_closed()
            return

        await asyncio.sleep(1)


async def main() -> None:
    async with darkriftpy.serve(handle_client, "127.0.0.1", 4296, 4296) as server:
        await asyncio.Future()


if __name__ == "__main__":
    asyncio.run(main())

User defined messages

darkriftpy provides a convinient way to create/send/receive user-defined messages. There is a Message class that can be used as a base class for user-defined ones. The Darkrift tag of a user-defined message is defined by passing the keyword tag argument in the class definition:

import darkriftpy

class ChooseMessage(darkriftpy.Message, tag=1):
    ...

For now, the ChooseMessage message contains no payload. Since the ChooseMessage class is implicitly decorated with the @dataclass decorator, the user can define class variables with type annotations which will be automatically deserialized from or serialized to a binary stream using DarkriftReader and DarkriftWriter classes. Only the following native types can be used as a class variable type: str, bytes, bool, float. Since Darkrift2 allows to use types which are not natively available in python, the darkriftpy.types module provides NewType extensions to cover all the required Darkrift2 types.

import darkriftpy
from darkriftpy.types import int32


class ChooseMessage(darkriftpy.Message, tag=1):
    items: list[int32]

As you can see we used the int32 type from the darkriftpy.types module to define 4 byte signed integer. Since the ChooseMessage class is implicitly decorated with the @dataclass decorator and there is no custom constructor, the following constructor will be created automatically: __init__(self, items: lsit[int32])

Therefore, the ChooseMessage class can be instantiated as follows:

import random


import darkriftpy
from darkriftpy.types import int32


MIN_INT32 = (2 ** 31) * -1
MAX_INT32 = 2 ** 31 - 2


class ChooseMessage(darkriftpy.Message, tag=1):
    items: list[int32]


message = ChooseMessage([random.randint(MIN_INT32, MAX_INT32) for _ in range(10)])

# message.items contains a list with 10 int32 integers

Since the darkriftpy.Message is inherited from darkriftpy.DarkriftMessage the user-defined message can be passed as is to the send method of the darkriftpy.DarkriftClient object.

To convert a received darkriftpy.DarkriftMessage message to the user-defined one, the user can do the following:

...

client: darkriftpy.DarkriftClient
message: darkriftpy.DarkriftMessage = await client.recv()

try:
    choose_message = ChooseMessage.read(message.get_reader())
except RuntimeError:
    # failed to parse the received message
    ...

print(choose_message.items)

The darkriftpy package provides the MessageContainer class to simplify the message serialization and de-siarilization.

import darkriftpy
from darkriftpy.types import int32


messages = darkriftpy.MessageContainer()


@messages.add
class ChooseMessage(darkriftpy.Message, tag=1):
    items: list[int32]


@messages.add
class ChoiceMessage(darkriftpy.Message, tag=2):
    item: int32

...

client: darkriftpy.DarkriftClient
message: darkriftpy.DarkriftMessage = await client.recv()

try:
    msg = messages.convert(message)
except RuntimeError:
    # failed to convert the received darkrift message
    # to the user-defined one

if isinstance(msg, ChooseMessage):
    print(msg.items)
elif isinstance(msg, ChoiceMessage):
    print(msg.item)

We used the add method of the MessageContainer class as decorator to add the user-defined class into the message container messages.
The convert method of the MessageContainer class allows us to convert a raw darkrift message to the user-defined specific one.

Using all these we can create a client wrapper that will return already deserialized messages.

from collections.abc import AsyncIterator


import darkriftpy


class Client:
    def __init__(
        self, client: darkriftpy.DarkriftClient, messages: darkriftpy.MessageContainer
    ):
        self._client = client
        self._messages = messages

    async def recv(self) -> darkriftpy.DarkriftMessage:
        message = await self._client.recv()

        try:
            return self._messages.convert(message)
        except RuntimeError:
            # just return the message as is
            pass

        return message

    async def send(self, message: darkriftpy.DarkriftMessage, reliable: bool = True) -> None:
        await self._client.send(message, reliable)

    def __aiter__(self) -> AsyncIterator[darkriftpy.DarkriftMessage]:
        return self

    async def __anext__(self) -> darkriftpy.DarkriftMessage:
        """
        Returns the next message.

        Stop iteration when the connection is closed.

        """
        try:
            return await self.recv()
        except darkrift.ConnectionClosedError:
            raise StopAsyncIteration()

So now we can use the client wrapper to send and receive user specified messages.

Let's update the first example to use all described features.

client.py:

import asyncio
import random
from collections.abc import AsyncIterator

import darkriftpy
from darkriftpy.types import int32


RND_POOL = 20

MIN_INT32 = (2 ** 31) * -1
MAX_INT32 = 2 ** 31 - 2


messages = darkriftpy.MessageContainer()


@messages.add
class ChooseMessage(darkriftpy.Message, tag=1):
    items: list[int32]


@messages.add
class ChoiceMessage(darkriftpy.Message, tag=2):
    item: int32


class Client:
    def __init__(
        self, client: darkriftpy.DarkriftClient, messages: darkriftpy.MessageContainer
    ):
        self._client = client
        self._messages = messages

    async def recv(self) -> darkriftpy.DarkriftMessage:
        message = await self._client.recv()

        try:
            return self._messages.convert(message)
        except RuntimeError:
            # just return the message as is
            pass

        return message

    async def send(
        self, message: darkriftpy.DarkriftMessage, reliable: bool = True
    ) -> None:
        await self._client.send(message, reliable)

    def __aiter__(self) -> AsyncIterator[darkriftpy.DarkriftMessage]:
        return self

    async def __anext__(self) -> darkriftpy.DarkriftMessage:
        """
        Returns the next message.

        Stop iteration when the connection is closed.

        """
        try:
            return await self.recv()
        except darkrift.ConnectionClosedError:
            raise StopAsyncIteration()


async def process_message(message: darkriftpy.DarkriftMessage) -> None:
    if not isinstance(message, ChoiceMessage):
        raise ValueError("wrong message received")

    print(f"the server chose the number: {message.item}")


async def main():
    try:
        c: darkriftpy.DarkriftClient
        async with darkriftpy.connect("127.0.0.1", 4296, 4296) as c:
            client = Client(c, messages)
            choose_message = ChooseMessage(
                [random.randint(MIN_INT32, MAX_INT32) for _ in range(RND_POOL)]
            )

            await client.send(choose_message)

            async for message in client:
                await process_message(message)

            print("Connection has been closed by the server")

    except ConnectionError:
        print("failed to connect to the server")


if __name__ == "__main__":
    asyncio.run(main())

server.py:

import asyncio
import random
from collections.abc import AsyncIterator

import darkriftpy
from darkriftpy.types import int32


messages = darkriftpy.MessageContainer()


@messages.add
class ChooseMessage(darkriftpy.Message, tag=1):
    items: list[int32]


@messages.add
class ChoiceMessage(darkriftpy.Message, tag=2):
    item: int32


class Client:
    def __init__(
        self, client: darkriftpy.DarkriftClient, messages: darkriftpy.MessageContainer
    ):
        self._client = client
        self._messages = messages

    async def recv(self) -> darkriftpy.DarkriftMessage:
        message = await self._client.recv()

        try:
            return self._messages.convert(message)
        except RuntimeError:
            # just return the message as is
            pass

        return message

    async def send(
        self, message: darkriftpy.DarkriftMessage, reliable: bool = True
    ) -> None:
        await self._client.send(message, reliable)

    def __aiter__(self) -> AsyncIterator[darkriftpy.DarkriftMessage]:
        return self

    async def __anext__(self) -> darkriftpy.DarkriftMessage:
        """
        Returns the next message.

        Stop iteration when the connection is closed.

        """
        try:
            return await self.recv()
        except darkrift.ConnectionClosedError:
            raise StopAsyncIteration()


async def handle_client(c: darkriftpy.DarkriftClient) -> None:
    client = Client(c, messages)

    message = await client.recv()
    if not isinstance(message, ChooseMessage):
        raise RuntimeError("wrong client message received")

        c.close()
        await c.wait_closed()
        return

    while True:
        choice_message = ChoiceMessage(random.choice(message.items))

        try:
            await client.send(choice_message)
        except darkriftpy.ConnectionClosedError:
            print(f"the client({c.connection_id}) has been disconnected")
            await c.wait_closed()
            return

        await asyncio.sleep(1)


async def main():
    async with darkriftpy.serve(handle_client, "127.0.0.1", 4296, 4296) as server:
        await asyncio.Future()


if __name__ == "__main__":
    asyncio.run(main())

TODO

[ ] - Add multiprocessing support to improve performance and scalability (Fork + Multiplexing I/O).
[ ] - Cover the codebase with tests ;).