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server.py
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server.py
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# Copyright (C) 2014-2021 Greenbone Networks GmbH
#
# SPDX-License-Identifier: AGPL-3.0-or-later
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
Module for serving and streaming data
"""
import logging
import socket
import ssl
import time
import threading
import socketserver
from abc import ABC, abstractmethod
from pathlib import Path
from typing import Callable, Optional, Tuple, Union
from ospd.errors import OspdError
logger = logging.getLogger(__name__)
DEFAULT_BUFSIZE = 1024
class Stream:
def __init__(self, sock: socket.socket, stream_timeout: int):
self.socket = sock
self.socket.settimeout(stream_timeout)
def close(self):
"""Close the stream"""
try:
self.socket.shutdown(socket.SHUT_RDWR)
except OSError as e:
logger.debug(
"Ignoring error while shutting down the connection. %s", e
)
self.socket.close()
def read(self, bufsize: Optional[int] = DEFAULT_BUFSIZE) -> bytes:
"""Read at maximum bufsize data from the stream"""
data = self.socket.recv(bufsize)
if not data:
logger.debug('Client closed the connection')
return data
def write(self, data: bytes) -> bool:
"""Send data in chunks of DEFAULT_BUFSIZE to the client"""
b_start = 0
b_end = DEFAULT_BUFSIZE
ret_success = True
while True:
if b_end > len(data):
try:
self.socket.send(data[b_start:])
except (socket.error, BrokenPipeError) as e:
logger.error("Error sending data to the client. %s", e)
ret_success = False
finally:
return ret_success # pylint: disable=lost-exception
try:
b_sent = self.socket.send(data[b_start:b_end])
except (socket.error, BrokenPipeError) as e:
logger.error("Error sending data to the client. %s", e)
return False
b_start = b_end
b_end += b_sent
return ret_success
StreamCallbackType = Callable[[Stream], None]
InetAddress = Tuple[str, int]
def validate_cacert_file(cacert: str):
"""Check if provided file is a valid CA Certificate"""
try:
context = ssl.create_default_context(cafile=cacert)
except AttributeError:
# Python version < 2.7.9
return
except IOError:
raise OspdError('CA Certificate not found') from None
try:
not_after = context.get_ca_certs()[0]['notAfter']
not_after = ssl.cert_time_to_seconds(not_after)
not_before = context.get_ca_certs()[0]['notBefore']
not_before = ssl.cert_time_to_seconds(not_before)
except (KeyError, IndexError):
raise OspdError('CA Certificate is erroneous') from None
now = int(time.time())
if not_after < now:
raise OspdError('CA Certificate expired')
if not_before > now:
raise OspdError('CA Certificate not active yet')
class RequestHandler(socketserver.BaseRequestHandler):
"""Class to handle the request."""
def handle(self):
self.server.handle_request(self.request, self.client_address)
class BaseServer(ABC):
def __init__(self, stream_timeout: int):
self.server = None
self.stream_timeout = stream_timeout
@abstractmethod
def start(self, stream_callback: StreamCallbackType):
"""Starts a server with capabilities to handle multiple client
connections simultaneously.
If a new client connects the stream_callback is called with a Stream
Arguments:
stream_callback (function): Callback function to be called when
a stream is ready
"""
def close(self):
"""Shutdown the server"""
self.server.shutdown()
self.server.server_close()
@abstractmethod
def handle_request(self, request, client_address):
"""Handle an incoming client request"""
def _start_threading_server(self):
server_thread = threading.Thread(target=self.server.serve_forever)
server_thread.daemon = True
server_thread.start()
class SocketServerMixin:
# Use daemon mode to circrumvent a memory leak
# (reported at https://bugs.python.org/issue37193).
#
# Daemonic threads are killed immediately by the python interpreter without
# waiting for until they are finished.
#
# Maybe block_on_close = True could work too.
# In that case the interpreter waits for the threads to finish but doesn't
# track them in the _threads list.
daemon_threads = True
def __init__(self, server: BaseServer, address: Union[str, InetAddress]):
self.server = server
super().__init__(address, RequestHandler, bind_and_activate=True)
def handle_request(self, request, client_address):
self.server.handle_request(request, client_address)
class ThreadedUnixSocketServer(
SocketServerMixin,
socketserver.ThreadingUnixStreamServer,
):
pass
class ThreadedTlsSocketServer(
SocketServerMixin,
socketserver.ThreadingTCPServer,
):
pass
class UnixSocketServer(BaseServer):
"""Server for accepting connections via a Unix domain socket"""
def __init__(self, socket_path: str, socket_mode: str, stream_timeout: int):
super().__init__(stream_timeout)
self.socket_path = Path(socket_path)
self.socket_mode = int(socket_mode, 8)
def _cleanup_socket(self):
if self.socket_path.exists():
self.socket_path.unlink()
def _create_parent_dirs(self):
# create all parent directories for the socket path
parent = self.socket_path.parent
parent.mkdir(parents=True, exist_ok=True)
def start(self, stream_callback: StreamCallbackType):
self._cleanup_socket()
self._create_parent_dirs()
try:
self.stream_callback = stream_callback
self.server = ThreadedUnixSocketServer(self, str(self.socket_path))
self._start_threading_server()
except OSError as e:
logger.error("Couldn't bind socket on %s", str(self.socket_path))
raise OspdError(
f"Couldn't bind socket on {str(self.socket_path)}. {e}"
) from e
if self.socket_path.exists():
self.socket_path.chmod(self.socket_mode)
def close(self):
super().close()
self._cleanup_socket()
def handle_request(self, request, client_address):
logger.debug("New request from %s", str(self.socket_path))
stream = Stream(request, self.stream_timeout)
self.stream_callback(stream)
class TlsServer(BaseServer):
"""Server for accepting TLS encrypted connections via a TCP socket"""
def __init__(
self,
address: str,
port: int,
cert_file: str,
key_file: str,
ca_file: str,
stream_timeout: int,
):
super().__init__(stream_timeout)
self.socket = (address, port)
if not Path(cert_file).exists():
raise OspdError(f'cert file {cert_file} not found')
if not Path(key_file).exists():
raise OspdError(f'key file {key_file} not found')
if not Path(ca_file).exists():
raise OspdError(f'CA file {ca_file} not found')
validate_cacert_file(ca_file)
protocol = ssl.PROTOCOL_SSLv23
self.tls_context = ssl.SSLContext(protocol)
self.tls_context.verify_mode = ssl.CERT_REQUIRED
self.tls_context.load_cert_chain(cert_file, keyfile=key_file)
self.tls_context.load_verify_locations(ca_file)
def start(self, stream_callback: StreamCallbackType):
try:
self.stream_callback = stream_callback
self.server = ThreadedTlsSocketServer(self, self.socket)
self._start_threading_server()
except OSError as e:
logger.error(
"Couldn't bind socket on %s:%s", self.socket[0], self.socket[1]
)
raise OspdError(
f"Couldn't bind socket on {self.socket[0]}:{self.socket[1]}. "
f"{e}"
) from e
def handle_request(self, request, client_address):
logger.debug("New connection from %s", client_address)
req_socket = self.tls_context.wrap_socket(request, server_side=True)
stream = Stream(req_socket, self.stream_timeout)
self.stream_callback(stream)