Mini Shell
"""
A library for integrating :doc:`pyOpenSSL <pyopenssl:index>` with Cheroot.
The :py:mod:`OpenSSL <pyopenssl:OpenSSL>` module must be importable
for SSL/TLS/HTTPS functionality.
You can obtain it from `here <https://github.com/pyca/pyopenssl>`_.
To use this module, set :py:attr:`HTTPServer.ssl_adapter
<cheroot.server.HTTPServer.ssl_adapter>` to an instance of
:py:class:`ssl.Adapter <cheroot.ssl.Adapter>`.
There are two ways to use :abbr:`TLS (Transport-Level Security)`:
Method One
----------
* :py:attr:`ssl_adapter.context
<cheroot.ssl.pyopenssl.pyOpenSSLAdapter.context>`: an instance of
:py:class:`SSL.Context <pyopenssl:OpenSSL.SSL.Context>`.
If this is not None, it is assumed to be an :py:class:`SSL.Context
<pyopenssl:OpenSSL.SSL.Context>` instance, and will be passed to
:py:class:`SSL.Connection <pyopenssl:OpenSSL.SSL.Connection>` on bind().
The developer is responsible for forming a valid :py:class:`Context
<pyopenssl:OpenSSL.SSL.Context>` object. This
approach is to be preferred for more flexibility, e.g. if the cert and
key are streams instead of files, or need decryption, or
:py:data:`SSL.SSLv3_METHOD <pyopenssl:OpenSSL.SSL.SSLv3_METHOD>`
is desired instead of the default :py:data:`SSL.SSLv23_METHOD
<pyopenssl:OpenSSL.SSL.SSLv3_METHOD>`, etc. Consult
the :doc:`pyOpenSSL <pyopenssl:api/ssl>` documentation for
complete options.
Method Two (shortcut)
---------------------
* :py:attr:`ssl_adapter.certificate
<cheroot.ssl.pyopenssl.pyOpenSSLAdapter.certificate>`: the file name
of the server's TLS certificate.
* :py:attr:`ssl_adapter.private_key
<cheroot.ssl.pyopenssl.pyOpenSSLAdapter.private_key>`: the file name
of the server's private key file.
Both are :py:data:`None` by default. If :py:attr:`ssl_adapter.context
<cheroot.ssl.pyopenssl.pyOpenSSLAdapter.context>` is :py:data:`None`,
but ``.private_key`` and ``.certificate`` are both given and valid, they
will be read, and the context will be automatically created from them.
.. spelling::
pyopenssl
"""
import socket
import sys
import threading
import time
try:
import OpenSSL.version
from OpenSSL import SSL
from OpenSSL import crypto
try:
ssl_conn_type = SSL.Connection
except AttributeError:
ssl_conn_type = SSL.ConnectionType
except ImportError:
SSL = None
from . import Adapter
from .. import errors, server as cheroot_server
from ..makefile import StreamReader, StreamWriter
class SSLFileobjectMixin:
"""Base mixin for a TLS socket stream."""
ssl_timeout = 3
ssl_retry = .01
# FIXME:
def _safe_call(self, is_reader, call, *args, **kwargs): # noqa: C901
"""Wrap the given call with TLS error-trapping.
is_reader: if False EOF errors will be raised. If True, EOF errors
will return "" (to emulate normal sockets).
"""
start = time.time()
while True:
try:
return call(*args, **kwargs)
except SSL.WantReadError:
# Sleep and try again. This is dangerous, because it means
# the rest of the stack has no way of differentiating
# between a "new handshake" error and "client dropped".
# Note this isn't an endless loop: there's a timeout below.
# Ref: https://stackoverflow.com/a/5133568/595220
time.sleep(self.ssl_retry)
except SSL.WantWriteError:
time.sleep(self.ssl_retry)
except SSL.SysCallError as e:
if is_reader and e.args == (-1, 'Unexpected EOF'):
return b''
errnum = e.args[0]
if is_reader and errnum in errors.socket_errors_to_ignore:
return b''
raise socket.error(errnum)
except SSL.Error as e:
if is_reader and e.args == (-1, 'Unexpected EOF'):
return b''
thirdarg = None
try:
thirdarg = e.args[0][0][2]
except IndexError:
pass
if thirdarg == 'http request':
# The client is talking HTTP to an HTTPS server.
raise errors.NoSSLError()
raise errors.FatalSSLAlert(*e.args)
if time.time() - start > self.ssl_timeout:
raise socket.timeout('timed out')
def recv(self, size):
"""Receive message of a size from the socket."""
return self._safe_call(
True,
super(SSLFileobjectMixin, self).recv,
size,
)
def readline(self, size=-1):
"""Receive message of a size from the socket.
Matches the following interface:
https://docs.python.org/3/library/io.html#io.IOBase.readline
"""
return self._safe_call(
True,
super(SSLFileobjectMixin, self).readline,
size,
)
def sendall(self, *args, **kwargs):
"""Send whole message to the socket."""
return self._safe_call(
False,
super(SSLFileobjectMixin, self).sendall,
*args, **kwargs,
)
def send(self, *args, **kwargs):
"""Send some part of message to the socket."""
return self._safe_call(
False,
super(SSLFileobjectMixin, self).send,
*args, **kwargs,
)
class SSLFileobjectStreamReader(SSLFileobjectMixin, StreamReader):
"""SSL file object attached to a socket object."""
class SSLFileobjectStreamWriter(SSLFileobjectMixin, StreamWriter):
"""SSL file object attached to a socket object."""
class SSLConnectionProxyMeta:
"""Metaclass for generating a bunch of proxy methods."""
def __new__(mcl, name, bases, nmspc):
"""Attach a list of proxy methods to a new class."""
proxy_methods = (
'get_context', 'pending', 'send', 'write', 'recv', 'read',
'renegotiate', 'bind', 'listen', 'connect', 'accept',
'setblocking', 'fileno', 'close', 'get_cipher_list',
'getpeername', 'getsockname', 'getsockopt', 'setsockopt',
'makefile', 'get_app_data', 'set_app_data', 'state_string',
'sock_shutdown', 'get_peer_certificate', 'want_read',
'want_write', 'set_connect_state', 'set_accept_state',
'connect_ex', 'sendall', 'settimeout', 'gettimeout',
'shutdown',
)
proxy_methods_no_args = (
'shutdown',
)
proxy_props = (
'family',
)
def lock_decorator(method):
"""Create a proxy method for a new class."""
def proxy_wrapper(self, *args):
self._lock.acquire()
try:
new_args = (
args[:] if method not in proxy_methods_no_args else []
)
return getattr(self._ssl_conn, method)(*new_args)
finally:
self._lock.release()
return proxy_wrapper
for m in proxy_methods:
nmspc[m] = lock_decorator(m)
nmspc[m].__name__ = m
def make_property(property_):
"""Create a proxy method for a new class."""
def proxy_prop_wrapper(self):
return getattr(self._ssl_conn, property_)
proxy_prop_wrapper.__name__ = property_
return property(proxy_prop_wrapper)
for p in proxy_props:
nmspc[p] = make_property(p)
# Doesn't work via super() for some reason.
# Falling back to type() instead:
return type(name, bases, nmspc)
class SSLConnection(metaclass=SSLConnectionProxyMeta):
r"""A thread-safe wrapper for an ``SSL.Connection``.
:param tuple args: the arguments to create the wrapped \
:py:class:`SSL.Connection(*args) \
<pyopenssl:OpenSSL.SSL.Connection>`
"""
def __init__(self, *args):
"""Initialize SSLConnection instance."""
self._ssl_conn = SSL.Connection(*args)
self._lock = threading.RLock()
class pyOpenSSLAdapter(Adapter):
"""A wrapper for integrating pyOpenSSL with Cheroot."""
certificate = None
"""The file name of the server's TLS certificate."""
private_key = None
"""The file name of the server's private key file."""
certificate_chain = None
"""Optional. The file name of CA's intermediate certificate bundle.
This is needed for cheaper "chained root" TLS certificates,
and should be left as :py:data:`None` if not required."""
context = None
"""
An instance of :py:class:`SSL.Context <pyopenssl:OpenSSL.SSL.Context>`.
"""
ciphers = None
"""The ciphers list of TLS."""
def __init__(
self, certificate, private_key, certificate_chain=None,
ciphers=None,
):
"""Initialize OpenSSL Adapter instance."""
if SSL is None:
raise ImportError('You must install pyOpenSSL to use HTTPS.')
super(pyOpenSSLAdapter, self).__init__(
certificate, private_key, certificate_chain, ciphers,
)
self._environ = None
def bind(self, sock):
"""Wrap and return the given socket."""
if self.context is None:
self.context = self.get_context()
conn = SSLConnection(self.context, sock)
self._environ = self.get_environ()
return conn
def wrap(self, sock):
"""Wrap and return the given socket, plus WSGI environ entries."""
# pyOpenSSL doesn't perform the handshake until the first read/write
# forcing the handshake to complete tends to result in the connection
# closing so we can't reliably access protocol/client cert for the env
return sock, self._environ.copy()
def get_context(self):
"""Return an ``SSL.Context`` from self attributes.
Ref: :py:class:`SSL.Context <pyopenssl:OpenSSL.SSL.Context>`
"""
# See https://code.activestate.com/recipes/442473/
c = SSL.Context(SSL.SSLv23_METHOD)
c.use_privatekey_file(self.private_key)
if self.certificate_chain:
c.load_verify_locations(self.certificate_chain)
c.use_certificate_file(self.certificate)
return c
def get_environ(self):
"""Return WSGI environ entries to be merged into each request."""
ssl_environ = {
'wsgi.url_scheme': 'https',
'HTTPS': 'on',
'SSL_VERSION_INTERFACE': '%s %s/%s Python/%s' % (
cheroot_server.HTTPServer.version,
OpenSSL.version.__title__, OpenSSL.version.__version__,
sys.version,
),
'SSL_VERSION_LIBRARY': SSL.SSLeay_version(
SSL.SSLEAY_VERSION,
).decode(),
}
if self.certificate:
# Server certificate attributes
with open(self.certificate, 'rb') as cert_file:
cert = crypto.load_certificate(
crypto.FILETYPE_PEM, cert_file.read(),
)
ssl_environ.update({
'SSL_SERVER_M_VERSION': cert.get_version(),
'SSL_SERVER_M_SERIAL': cert.get_serial_number(),
# 'SSL_SERVER_V_START':
# Validity of server's certificate (start time),
# 'SSL_SERVER_V_END':
# Validity of server's certificate (end time),
})
for prefix, dn in [
('I', cert.get_issuer()),
('S', cert.get_subject()),
]:
# X509Name objects don't seem to have a way to get the
# complete DN string. Use str() and slice it instead,
# because str(dn) == "<X509Name object '/C=US/ST=...'>"
dnstr = str(dn)[18:-2]
wsgikey = 'SSL_SERVER_%s_DN' % prefix
ssl_environ[wsgikey] = dnstr
# The DN should be of the form: /k1=v1/k2=v2, but we must allow
# for any value to contain slashes itself (in a URL).
while dnstr:
pos = dnstr.rfind('=')
dnstr, value = dnstr[:pos], dnstr[pos + 1:]
pos = dnstr.rfind('/')
dnstr, key = dnstr[:pos], dnstr[pos + 1:]
if key and value:
wsgikey = 'SSL_SERVER_%s_DN_%s' % (prefix, key)
ssl_environ[wsgikey] = value
return ssl_environ
def makefile(self, sock, mode='r', bufsize=-1):
"""Return socket file object."""
cls = (
SSLFileobjectStreamReader
if 'r' in mode else
SSLFileobjectStreamWriter
)
if SSL and isinstance(sock, ssl_conn_type):
wrapped_socket = cls(sock, mode, bufsize)
wrapped_socket.ssl_timeout = sock.gettimeout()
return wrapped_socket
# This is from past:
# TODO: figure out what it's meant for
else:
return cheroot_server.CP_fileobject(sock, mode, bufsize)
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