339 lines
12 KiB
Python
339 lines
12 KiB
Python
from __future__ import annotations
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import logging
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import re
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import ssl
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import sys
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from collections.abc import Callable, Mapping
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from dataclasses import dataclass
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from functools import wraps
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from typing import Any, Tuple, TypeVar
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from .. import (
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BrokenResourceError,
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EndOfStream,
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aclose_forcefully,
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get_cancelled_exc_class,
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)
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from .._core._typedattr import TypedAttributeSet, typed_attribute
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from ..abc import AnyByteStream, ByteStream, Listener, TaskGroup
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if sys.version_info >= (3, 11):
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from typing import TypeVarTuple, Unpack
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else:
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from typing_extensions import TypeVarTuple, Unpack
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T_Retval = TypeVar("T_Retval")
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PosArgsT = TypeVarTuple("PosArgsT")
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_PCTRTT = Tuple[Tuple[str, str], ...]
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_PCTRTTT = Tuple[_PCTRTT, ...]
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class TLSAttribute(TypedAttributeSet):
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"""Contains Transport Layer Security related attributes."""
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#: the selected ALPN protocol
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alpn_protocol: str | None = typed_attribute()
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#: the channel binding for type ``tls-unique``
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channel_binding_tls_unique: bytes = typed_attribute()
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#: the selected cipher
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cipher: tuple[str, str, int] = typed_attribute()
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#: the peer certificate in dictionary form (see :meth:`ssl.SSLSocket.getpeercert`
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# for more information)
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peer_certificate: None | (dict[str, str | _PCTRTTT | _PCTRTT]) = typed_attribute()
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#: the peer certificate in binary form
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peer_certificate_binary: bytes | None = typed_attribute()
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#: ``True`` if this is the server side of the connection
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server_side: bool = typed_attribute()
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#: ciphers shared by the client during the TLS handshake (``None`` if this is the
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#: client side)
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shared_ciphers: list[tuple[str, str, int]] | None = typed_attribute()
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#: the :class:`~ssl.SSLObject` used for encryption
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ssl_object: ssl.SSLObject = typed_attribute()
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#: ``True`` if this stream does (and expects) a closing TLS handshake when the
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#: stream is being closed
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standard_compatible: bool = typed_attribute()
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#: the TLS protocol version (e.g. ``TLSv1.2``)
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tls_version: str = typed_attribute()
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@dataclass(eq=False)
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class TLSStream(ByteStream):
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"""
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A stream wrapper that encrypts all sent data and decrypts received data.
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This class has no public initializer; use :meth:`wrap` instead.
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All extra attributes from :class:`~TLSAttribute` are supported.
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:var AnyByteStream transport_stream: the wrapped stream
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"""
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transport_stream: AnyByteStream
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standard_compatible: bool
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_ssl_object: ssl.SSLObject
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_read_bio: ssl.MemoryBIO
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_write_bio: ssl.MemoryBIO
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@classmethod
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async def wrap(
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cls,
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transport_stream: AnyByteStream,
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*,
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server_side: bool | None = None,
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hostname: str | None = None,
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ssl_context: ssl.SSLContext | None = None,
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standard_compatible: bool = True,
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) -> TLSStream:
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"""
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Wrap an existing stream with Transport Layer Security.
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This performs a TLS handshake with the peer.
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:param transport_stream: a bytes-transporting stream to wrap
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:param server_side: ``True`` if this is the server side of the connection,
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``False`` if this is the client side (if omitted, will be set to ``False``
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if ``hostname`` has been provided, ``False`` otherwise). Used only to create
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a default context when an explicit context has not been provided.
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:param hostname: host name of the peer (if host name checking is desired)
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:param ssl_context: the SSLContext object to use (if not provided, a secure
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default will be created)
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:param standard_compatible: if ``False``, skip the closing handshake when
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closing the connection, and don't raise an exception if the peer does the
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same
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:raises ~ssl.SSLError: if the TLS handshake fails
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"""
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if server_side is None:
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server_side = not hostname
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if not ssl_context:
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purpose = (
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ssl.Purpose.CLIENT_AUTH if server_side else ssl.Purpose.SERVER_AUTH
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)
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ssl_context = ssl.create_default_context(purpose)
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# Re-enable detection of unexpected EOFs if it was disabled by Python
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if hasattr(ssl, "OP_IGNORE_UNEXPECTED_EOF"):
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ssl_context.options &= ~ssl.OP_IGNORE_UNEXPECTED_EOF
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bio_in = ssl.MemoryBIO()
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bio_out = ssl.MemoryBIO()
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ssl_object = ssl_context.wrap_bio(
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bio_in, bio_out, server_side=server_side, server_hostname=hostname
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)
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wrapper = cls(
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transport_stream=transport_stream,
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standard_compatible=standard_compatible,
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_ssl_object=ssl_object,
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_read_bio=bio_in,
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_write_bio=bio_out,
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)
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await wrapper._call_sslobject_method(ssl_object.do_handshake)
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return wrapper
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async def _call_sslobject_method(
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self, func: Callable[[Unpack[PosArgsT]], T_Retval], *args: Unpack[PosArgsT]
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) -> T_Retval:
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while True:
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try:
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result = func(*args)
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except ssl.SSLWantReadError:
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try:
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# Flush any pending writes first
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if self._write_bio.pending:
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await self.transport_stream.send(self._write_bio.read())
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data = await self.transport_stream.receive()
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except EndOfStream:
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self._read_bio.write_eof()
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except OSError as exc:
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self._read_bio.write_eof()
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self._write_bio.write_eof()
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raise BrokenResourceError from exc
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else:
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self._read_bio.write(data)
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except ssl.SSLWantWriteError:
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await self.transport_stream.send(self._write_bio.read())
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except ssl.SSLSyscallError as exc:
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self._read_bio.write_eof()
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self._write_bio.write_eof()
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raise BrokenResourceError from exc
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except ssl.SSLError as exc:
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self._read_bio.write_eof()
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self._write_bio.write_eof()
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if (
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isinstance(exc, ssl.SSLEOFError)
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or "UNEXPECTED_EOF_WHILE_READING" in exc.strerror
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):
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if self.standard_compatible:
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raise BrokenResourceError from exc
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else:
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raise EndOfStream from None
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raise
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else:
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# Flush any pending writes first
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if self._write_bio.pending:
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await self.transport_stream.send(self._write_bio.read())
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return result
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async def unwrap(self) -> tuple[AnyByteStream, bytes]:
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"""
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Does the TLS closing handshake.
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:return: a tuple of (wrapped byte stream, bytes left in the read buffer)
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"""
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await self._call_sslobject_method(self._ssl_object.unwrap)
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self._read_bio.write_eof()
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self._write_bio.write_eof()
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return self.transport_stream, self._read_bio.read()
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async def aclose(self) -> None:
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if self.standard_compatible:
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try:
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await self.unwrap()
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except BaseException:
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await aclose_forcefully(self.transport_stream)
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raise
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await self.transport_stream.aclose()
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async def receive(self, max_bytes: int = 65536) -> bytes:
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data = await self._call_sslobject_method(self._ssl_object.read, max_bytes)
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if not data:
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raise EndOfStream
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return data
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async def send(self, item: bytes) -> None:
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await self._call_sslobject_method(self._ssl_object.write, item)
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async def send_eof(self) -> None:
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tls_version = self.extra(TLSAttribute.tls_version)
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match = re.match(r"TLSv(\d+)(?:\.(\d+))?", tls_version)
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if match:
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major, minor = int(match.group(1)), int(match.group(2) or 0)
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if (major, minor) < (1, 3):
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raise NotImplementedError(
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f"send_eof() requires at least TLSv1.3; current "
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f"session uses {tls_version}"
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)
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raise NotImplementedError(
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"send_eof() has not yet been implemented for TLS streams"
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)
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@property
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def extra_attributes(self) -> Mapping[Any, Callable[[], Any]]:
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return {
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**self.transport_stream.extra_attributes,
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TLSAttribute.alpn_protocol: self._ssl_object.selected_alpn_protocol,
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TLSAttribute.channel_binding_tls_unique: (
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self._ssl_object.get_channel_binding
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),
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TLSAttribute.cipher: self._ssl_object.cipher,
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TLSAttribute.peer_certificate: lambda: self._ssl_object.getpeercert(False),
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TLSAttribute.peer_certificate_binary: lambda: self._ssl_object.getpeercert(
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True
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),
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TLSAttribute.server_side: lambda: self._ssl_object.server_side,
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TLSAttribute.shared_ciphers: lambda: self._ssl_object.shared_ciphers()
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if self._ssl_object.server_side
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else None,
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TLSAttribute.standard_compatible: lambda: self.standard_compatible,
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TLSAttribute.ssl_object: lambda: self._ssl_object,
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TLSAttribute.tls_version: self._ssl_object.version,
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}
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@dataclass(eq=False)
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class TLSListener(Listener[TLSStream]):
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"""
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A convenience listener that wraps another listener and auto-negotiates a TLS session
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on every accepted connection.
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If the TLS handshake times out or raises an exception,
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:meth:`handle_handshake_error` is called to do whatever post-mortem processing is
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deemed necessary.
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Supports only the :attr:`~TLSAttribute.standard_compatible` extra attribute.
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:param Listener listener: the listener to wrap
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:param ssl_context: the SSL context object
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:param standard_compatible: a flag passed through to :meth:`TLSStream.wrap`
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:param handshake_timeout: time limit for the TLS handshake
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(passed to :func:`~anyio.fail_after`)
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"""
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listener: Listener[Any]
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ssl_context: ssl.SSLContext
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standard_compatible: bool = True
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handshake_timeout: float = 30
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@staticmethod
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async def handle_handshake_error(exc: BaseException, stream: AnyByteStream) -> None:
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"""
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Handle an exception raised during the TLS handshake.
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This method does 3 things:
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#. Forcefully closes the original stream
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#. Logs the exception (unless it was a cancellation exception) using the
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``anyio.streams.tls`` logger
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#. Reraises the exception if it was a base exception or a cancellation exception
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:param exc: the exception
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:param stream: the original stream
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"""
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await aclose_forcefully(stream)
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# Log all except cancellation exceptions
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if not isinstance(exc, get_cancelled_exc_class()):
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# CPython (as of 3.11.5) returns incorrect `sys.exc_info()` here when using
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# any asyncio implementation, so we explicitly pass the exception to log
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# (https://github.com/python/cpython/issues/108668). Trio does not have this
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# issue because it works around the CPython bug.
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logging.getLogger(__name__).exception(
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"Error during TLS handshake", exc_info=exc
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)
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# Only reraise base exceptions and cancellation exceptions
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if not isinstance(exc, Exception) or isinstance(exc, get_cancelled_exc_class()):
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raise
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async def serve(
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self,
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handler: Callable[[TLSStream], Any],
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task_group: TaskGroup | None = None,
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) -> None:
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@wraps(handler)
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async def handler_wrapper(stream: AnyByteStream) -> None:
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from .. import fail_after
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try:
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with fail_after(self.handshake_timeout):
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wrapped_stream = await TLSStream.wrap(
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stream,
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ssl_context=self.ssl_context,
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standard_compatible=self.standard_compatible,
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)
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except BaseException as exc:
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await self.handle_handshake_error(exc, stream)
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else:
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await handler(wrapped_stream)
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await self.listener.serve(handler_wrapper, task_group)
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async def aclose(self) -> None:
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await self.listener.aclose()
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@property
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def extra_attributes(self) -> Mapping[Any, Callable[[], Any]]:
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return {
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TLSAttribute.standard_compatible: lambda: self.standard_compatible,
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}
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