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tls.py
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tls.py
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# SPDX-License-Identifier: MIT
# Copyright (c) 2018, Mathias Laurin
from __future__ import annotations
import enum
import errno
import os
import socket as _pysocket
import struct
import sys
from typing import Any, NoReturn, Optional, Tuple, Union, cast, overload
from ._tls import HandshakeStep as HandshakeStep
from ._tls import HelloVerifyRequest
from ._tls import MbedTLSBuffer as TLSWrappedBuffer
from ._tls import (
Purpose,
RaggedEOF,
TLSSession,
TrustStore,
WantReadError,
WantWriteError,
_BaseContext,
_tls_from_version,
_tls_to_version,
ciphers_available,
)
from ._tlsi import DTLSConfiguration as DTLSConfiguration
from ._tlsi import DTLSVersion as DTLSVersion
from ._tlsi import MaxFragmentLength as MaxFragmentLength
from ._tlsi import NextProtocol as NextProtocol
from ._tlsi import PrivateKey as PrivateKey
from ._tlsi import ServerNameCallback as ServerNameCallback
from ._tlsi import TLSConfiguration as TLSConfiguration
from ._tlsi import TLSVersion as TLSVersion
if sys.version_info < (3, 8):
from typing_extensions import Final
else:
from typing import Final
if sys.version_info < (3, 10):
from typing_extensions import TypeAlias
else:
from typing import TypeAlias
__all__ = (
"ClientContext",
"DTLSConfiguration",
"DTLSVersion",
"HelloVerifyRequest",
"MaxFragmentLength",
"NextProtocol",
"PrivateKey",
"Purpose",
"RaggedEOF",
"ServerContext",
"ServerNameCallback",
"TLSConfiguration",
"TLSRecordHeader",
"TLSSession",
"TLSVersion",
"TLSWrappedBuffer",
"TLSWrappedSocket",
"TrustStore",
"WantReadError",
"WantWriteError",
"ciphers_available",
)
# `_Address` stolen from `_socket.pyi`.
_Address: TypeAlias = Union[Tuple[Any, ...], str]
_WriteableBuffer: TypeAlias = Union[memoryview, bytearray]
class TLSRecordHeader:
"""Encode/decode TLS record protocol format."""
__slots__ = ("record_type", "version", "length")
fmt = "!BHH"
class RecordType(enum.IntEnum):
CHANGE_CIPHER_SPEC = 0x14
ALERT = 0x15
HANDSHAKE = 0x16
APPLICATION_DATA = 0x17
def __init__(
self,
record_type: Union[int, TLSRecordHeader.RecordType],
version: Union[int, Tuple[int, int], TLSVersion],
length: int,
) -> None:
def parse_version(
v: Union[int, Tuple[int, int], TLSVersion]
) -> TLSVersion:
if isinstance(v, TLSVersion):
return v
if isinstance(v, int):
return TLSVersion(v)
return TLSVersion(((v[0] & 0xFF) << 8) + v[1] & 0xFF)
self.record_type: Final = TLSRecordHeader.RecordType(record_type)
self.version: Final = parse_version(version)
self.length: Final = length
def __str__(self) -> str:
return "{}({}, {}, {})".format(
type(self).__name__,
self.record_type,
self.version,
self.length,
)
def __repr__(self) -> str:
return "{}({!r}, {!r}, {!r})".format(
type(self).__name__,
self.record_type,
self.version,
self.length,
)
def __eq__(self, other: object) -> bool:
if not isinstance(other, TLSRecordHeader):
return NotImplemented
return (
self.record_type is other.record_type
and self.version is other.version
and self.length == other.length
)
def __hash__(self) -> int:
return 0x5AFE ^ self.record_type ^ self.version.value ^ self.length
def __len__(self) -> int:
return 5
def __bytes__(self) -> bytes:
maj, min_ = _tls_from_version(self.version)
version = ((maj & 0xFF) << 8) + (min_ & 0xFF)
return struct.pack(
TLSRecordHeader.fmt,
self.record_type,
version,
self.length,
)
@classmethod
def from_bytes(cls, header: bytes) -> TLSRecordHeader:
record_type, maj_min_version, length = struct.unpack(
TLSRecordHeader.fmt, header[:5]
)
maj, min_ = (maj_min_version >> 8) & 0xFF, maj_min_version & 0xFF
return cls(
TLSRecordHeader.RecordType(record_type),
_tls_to_version((maj, min_)),
length,
)
class ClientContext(_BaseContext):
# _pep543.ClientContext
@property
def _purpose(self) -> Purpose:
return Purpose.CLIENT_AUTH
def wrap_socket(
self, socket: _pysocket.socket, server_hostname: Optional[str]
) -> TLSWrappedSocket:
"""Wrap an existing Python socket object ``socket`` and return a
``TLSWrappedSocket`` object. ``socket`` must be a ``SOCK_STREAM``
socket: all other socket types are unsupported.
Args:
socket: The socket to wrap.
server_hostname: The hostname of the service
which we are connecting to. Pass ``None`` if hostname
validation is not desired. This parameter has no
default value because opting-out hostname validation is
dangerous and should not be the default behavior.
"""
buffer = self.wrap_buffers(server_hostname)
return TLSWrappedSocket(socket, buffer)
def wrap_buffers(self, server_hostname: Optional[str]) -> TLSWrappedBuffer:
"""Create an in-memory stream for TLS."""
# PEP 543
return TLSWrappedBuffer(self, server_hostname)
class ServerContext(_BaseContext):
# _pep543.ServerContext
@property
def _purpose(self) -> Purpose:
return Purpose.SERVER_AUTH
def wrap_socket(self, socket: _pysocket.socket) -> TLSWrappedSocket:
"""Wrap an existing Python socket object ``socket``."""
buffer = self.wrap_buffers()
return TLSWrappedSocket(socket, buffer)
def wrap_buffers(self) -> TLSWrappedBuffer:
# PEP 543
return TLSWrappedBuffer(self)
class TLSWrappedSocket:
# pylint: disable=too-many-instance-attributes
# _pep543.TLSWrappedSocket
def __init__(
self, socket: _pysocket.socket, buffer: TLSWrappedBuffer
) -> None:
super().__init__()
self._socket = socket
self._buffer = buffer
self._context = buffer.context
self._closed = False
@property
def context(self) -> _BaseContext:
return self._buffer.context
@property
def _buffer(self) -> TLSWrappedBuffer:
return cast(TLSWrappedBuffer, self.__dict__["_buffer"])
@_buffer.setter
def _buffer(self, __buffer: TLSWrappedBuffer) -> None:
self.__dict__["_buffer"] = __buffer
self.setcookieparam = __buffer.setcookieparam
self.cipher = __buffer.cipher
self.negotiated_protocol = __buffer.negotiated_protocol
self.negotiated_tls_version = __buffer.negotiated_tls_version
@property
def _socket(self) -> _pysocket.socket:
return cast(_pysocket.socket, self.__dict__["_socket"])
@_socket.setter
def _socket(self, __socket: _pysocket.socket) -> None:
self.__dict__["_socket"] = __socket
# PEP 543 requires the full socket API.
self.family = __socket.family
self.proto = __socket.proto
self.type = __socket.type
self.bind = __socket.bind
self.connect = __socket.connect
self.connect_ex = __socket.connect_ex
self.fileno = __socket.fileno
self.getpeername = __socket.getpeername
self.getsockname = __socket.getsockname
self.getsockopt = __socket.getsockopt
self.listen = __socket.listen
self.makefile = __socket.makefile
self.setblocking = __socket.setblocking
self.settimeout = __socket.settimeout
self.gettimeout = __socket.gettimeout
self.setsockopt = __socket.setsockopt
def __getstate__(self) -> NoReturn:
raise TypeError(f"cannot pickle {self.__class__.__name__!r} object")
def __enter__(self) -> TLSWrappedSocket:
return self
def __exit__(self, *exc_info: object) -> None:
if not self._closed:
self.close()
def __str__(self) -> str:
return str(self._socket)
@property
def _handshake_state(self) -> HandshakeStep:
# pylint: disable=protected-access
return self._buffer._handshake_state
def setmtu(self, mtu: int) -> None:
"""Set Maxiumum Transport Unit (MTU) for DTLS.
Set to zero to unset.
Raises:
OverflowError: If value cannot be converted to UInt16.
"""
self._buffer.setmtu(mtu)
def accept(self) -> Tuple[TLSWrappedSocket, _Address]:
if self.type == _pysocket.SOCK_STREAM:
conn, address = self._socket.accept()
else:
_, address = self._socket.recvfrom(1024, _pysocket.MSG_PEEK)
# Use this socket to communicate with the client and bind
# another one for the next connection. This procedure is
# adapted from `mbedtls_net_accept()`.
sockname = self.getsockname()
conn = _pysocket.fromfd(self.fileno(), self.family, self.type)
conn.connect(address)
# Closing the socket on Python 2.7 and 3.4 invalidates
# the accessors. So we should get the values first.
family, type_, proto = self.family, self.type, self.proto
self.close()
self._socket = _pysocket.socket(family, type_, proto)
self.setsockopt(_pysocket.SOL_SOCKET, _pysocket.SO_REUSEADDR, 1)
self.bind(sockname)
if isinstance(self.context, ClientContext):
# pylint: disable=protected-access
# Probably not very useful but there is not reason to forbid it.
return (
self.context.wrap_socket(conn, self._buffer._server_hostname),
address,
)
assert isinstance(self.context, ServerContext)
return self.context.wrap_socket(conn), address
def close(self) -> None:
self._closed = True
self._buffer.shutdown()
self._socket.close()
def recv(self, bufsize: int, flags: int = 0) -> bytes:
encrypted = self._socket.recv(bufsize, flags)
if not encrypted:
return b""
self._buffer.receive_from_network(encrypted)
return self._buffer.read(bufsize)
def recv_into(
self,
buffer: _WriteableBuffer,
nbytes: Optional[int] = None,
flags: int = 0,
) -> int:
if nbytes is None:
bufsize = len(buffer)
else:
bufsize = min(len(buffer), nbytes)
encrypted = self._socket.recv(bufsize, flags)
if not encrypted:
return 0
self._buffer.receive_from_network(encrypted)
return self._buffer.readinto(buffer, len(encrypted))
def recvfrom(self, bufsize: int, flags: int = 0) -> Tuple[bytes, _Address]:
encrypted, addr = self._socket.recvfrom(bufsize, flags)
if not encrypted:
return b"", addr
self._buffer.receive_from_network(encrypted)
return self._buffer.read(bufsize), addr
def recvfrom_into(
self,
buffer: _WriteableBuffer,
nbytes: Optional[int] = None,
flags: int = 0,
) -> Tuple[int, _Address]:
encrypted, addr = self._socket.recvfrom(
nbytes if nbytes is not None else len(buffer), flags
)
if not encrypted:
return 0, addr
self._buffer.receive_from_network(encrypted)
return (
self._buffer.readinto(
buffer, nbytes if nbytes is not None else len(buffer)
),
addr,
)
def send(self, message: bytes, flags: int = 0) -> int:
# Maximum size supported by TLS is 16K (encrypted).
# mbedTLS defines it in MBEDTLS_SSL_MAX_CONTENT_LEN and
# MBEDTLS_SSL_IN_CONTENT_LEN/MBEDTLS_SSL_OUT_CONTENT_LEN.
amt = self._buffer.write(message)
encrypted = self._buffer.peek_outgoing(amt)
self._socket.send(encrypted, flags)
self._buffer.consume_outgoing(amt)
return len(message)
def sendall(self, message: bytes, flags: int = 0) -> None:
amt = self._buffer.write(message)
encrypted = self._buffer.peek_outgoing(amt)
self._buffer.consume_outgoing(amt)
self._socket.sendall(encrypted, flags)
def sendto(self, message: bytes, *args: Any) -> int:
if not 1 <= len(args) <= 2:
raise TypeError(
"sendto() takes 2 or 3 arguments (%i given)" % (1 + len(args))
)
amt = self._buffer.write(message)
encrypted = self._buffer.peek_outgoing(amt)
self._socket.sendto(encrypted, *args)
self._buffer.consume_outgoing(amt)
return len(message)
def shutdown(self, how: int) -> None:
self._buffer.shutdown()
self._socket.shutdown(how)
# PEP 543 adds the following methods.
@overload
def do_handshake(self) -> None:
...
@overload
def do_handshake(self, address: _Address) -> None:
...
@overload
def do_handshake(self, flags: int, address: _Address) -> None:
...
def do_handshake(self, *args): # type: ignore[no-untyped-def]
# pylint: disable=too-many-branches
if args and self.type is not _pysocket.SOCK_DGRAM:
raise OSError(errno.ENOTCONN, os.strerror(errno.ENOTCONN))
if len(args) == 0:
flags, address = 0, None
elif len(args) == 1:
flags, address = 0, args[0]
elif len(args) == 2:
assert isinstance(args[0], int)
flags, address = args
else:
raise TypeError("do_handshake() takes 0, 1, or 2 arguments")
while self._handshake_state is not HandshakeStep.HANDSHAKE_OVER:
try:
self._buffer.do_handshake()
except WantReadError as exc:
if address is None:
data = self._socket.recv(1024, flags)
else:
data, addr = self._socket.recvfrom(1024, flags)
if addr != address:
# The error may not be the clearest but we'd better
# bail out in any case.
raise OSError(
errno.ENOTCONN, os.strerror(errno.ENOTCONN)
) from exc
self._buffer.receive_from_network(data)
except WantWriteError:
in_transit = self._buffer.peek_outgoing(1024)
if address is None:
amt = self._socket.send(in_transit, flags)
else:
amt = self._socket.sendto(in_transit, flags, address)
self._buffer.consume_outgoing(amt)
def unwrap(self) -> _pysocket.socket:
self._buffer.shutdown()
return self._socket