234 lines
7.3 KiB
Python
234 lines
7.3 KiB
Python
# SPDX-License-Identifier: MIT
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#
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# Copyright (c) 2017 PySecretHandshake contributors (see AUTHORS for more details)
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in all
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# copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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"""Networking functionality"""
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from asyncio import StreamReader, StreamWriter, ensure_future, open_connection, start_server
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from typing import AsyncIterator, Awaitable, Callable, List, Optional
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from nacl.public import PrivateKey
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from nacl.signing import SigningKey
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from typing_extensions import Self, deprecated
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from .boxstream import BoxStream, UnboxStream, get_stream_pair
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from .crypto import SHSClientCrypto, SHSCryptoBase, SHSServerCrypto
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class SHSClientException(Exception):
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"""Base exception class for client errors"""
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class SHSDuplexStream:
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"""SHS duplex stream"""
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def __init__(self) -> None:
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self.write_stream: Optional[BoxStream] = None
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self.read_stream: Optional[UnboxStream] = None
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self.is_connected = False
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def write(self, data: bytes) -> None:
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"""Write data to the write stream"""
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assert self.write_stream
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self.write_stream.write(data)
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async def read(self) -> Optional[bytes]:
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"""Read data from the read stream"""
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assert self.read_stream
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return await self.read_stream.read()
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def close(self) -> None:
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"""Close the duplex stream"""
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if self.write_stream:
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self.write_stream.close()
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self.is_connected = False
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def __aiter__(self) -> AsyncIterator[bytes]:
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return self
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async def __anext__(self) -> bytes:
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msg = await self.read()
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if msg is None:
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raise StopAsyncIteration()
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return msg
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class SHSEndpoint:
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"""SHS endpoint"""
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def __init__(self) -> None:
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self._on_connect: Optional[Callable[[SHSDuplexStream], Awaitable[None]]] = None
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self.crypto: Optional[SHSCryptoBase] = None
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def on_connect(self, cb: Callable[[SHSDuplexStream], Awaitable[None]]) -> None:
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"""Set the function to be called when a new connection arrives"""
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self._on_connect = cb
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def close(self) -> None: # pragma: no cover
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"""Disconnect the endpoint"""
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raise NotImplementedError()
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@deprecated("Use close instead")
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def disconnect(self) -> None:
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"""Disconnect the endpoint"""
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self.close()
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class SHSServer(SHSEndpoint):
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"""SHS server"""
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def __init__(self, host: str, port: int, server_kp: SigningKey, application_key: Optional[bytes] = None):
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super().__init__()
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self.host = host
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self.port = port
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self.crypto: SHSServerCrypto = SHSServerCrypto(server_kp, application_key=application_key)
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self.connections: List[SHSServerConnection] = []
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async def _handshake(self, reader: StreamReader, writer: StreamWriter) -> None:
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assert self.crypto
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data = await reader.readexactly(64)
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if not self.crypto.verify_challenge(data):
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raise SHSClientException("Client challenge is not valid")
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writer.write(self.crypto.generate_challenge())
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data = await reader.readexactly(112)
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if not self.crypto.verify_client_auth(data):
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raise SHSClientException("Client auth is not valid")
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writer.write(self.crypto.generate_accept())
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async def handle_connection(self, reader: StreamReader, writer: StreamWriter) -> None:
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"""Handle incoming connections"""
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assert self.crypto
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self.crypto.clean()
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await self._handshake(reader, writer)
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keys = self.crypto.get_box_keys()
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self.crypto.clean()
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conn = SHSServerConnection.from_byte_streams(reader, writer, **keys)
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self.connections.append(conn)
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if self._on_connect:
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ensure_future(self._on_connect(conn))
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async def listen(self) -> None:
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"""Listen for connections"""
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await start_server(self.handle_connection, self.host, self.port)
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def close(self) -> None:
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for connection in self.connections:
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connection.close()
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@deprecated("Use close instead")
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def disconnect(self) -> None:
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self.close()
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class SHSServerConnection(SHSDuplexStream):
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"""SHS server connection"""
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def __init__(self, read_stream: UnboxStream, write_stream: BoxStream):
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super().__init__()
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self.read_stream = read_stream
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self.write_stream = write_stream
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@classmethod
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def from_byte_streams(cls, reader: StreamReader, writer: StreamWriter, **keys: bytes) -> Self:
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"""Create a server connection from an existing byte stream"""
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box_reader, box_writer = get_stream_pair(reader, writer, **keys)
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return cls(box_reader, box_writer)
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class SHSClient(SHSDuplexStream, SHSEndpoint):
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"""SHS client"""
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def __init__( # pylint: disable=too-many-arguments
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self,
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host: str,
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port: int,
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client_kp: SigningKey,
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server_pub_key: bytes,
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ephemeral_key: Optional[PrivateKey] = None,
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application_key: Optional[bytes] = None,
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):
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SHSDuplexStream.__init__(self)
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SHSEndpoint.__init__(self)
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self.host = host
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self.port = port
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self.writer: Optional[StreamWriter] = None
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self.crypto: SHSClientCrypto = SHSClientCrypto(
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client_kp,
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server_pub_key,
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ephemeral_key=ephemeral_key or PrivateKey.generate(),
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application_key=application_key,
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)
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async def _handshake(self, reader: StreamReader, writer: StreamWriter) -> None:
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writer.write(self.crypto.generate_challenge())
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data = await reader.readexactly(64)
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if not self.crypto.verify_server_challenge(data):
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raise SHSClientException("Server challenge is not valid")
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writer.write(self.crypto.generate_client_auth())
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data = await reader.readexactly(80)
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if not self.crypto.verify_server_accept(data):
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raise SHSClientException("Server accept is not valid")
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async def open(self) -> None:
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"""Open the TCP connection"""
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reader, writer = await open_connection(self.host, self.port)
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await self._handshake(reader, writer)
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keys = self.crypto.get_box_keys()
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self.crypto.clean()
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self.read_stream, self.write_stream = get_stream_pair(reader, writer, **keys)
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self.writer = writer
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self.is_connected = True
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if self._on_connect:
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await self._on_connect(self)
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