cloud-email/cryptography - python cryptography

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author	Andre Caron <andre.l.caron@gmail.com>	2015-06-02 23:47:11 -0400
committer	Ian Cordasco <graffatcolmingov@gmail.com>	2015-06-24 13:35:49 -0500
commit	d259ee51abae5a35e34f16ad74bfb1c62aa433d7 (patch)
tree	77e9eaf41e48381a00ddb44b59a9d9b398ff05d3 /src
parent	99d0f90ff256b540acb007458bbb07c467642368 (diff)
download	cryptography-d259ee51abae5a35e34f16ad74bfb1c62aa433d7.tar.gz cryptography-d259ee51abae5a35e34f16ad74bfb1c62aa433d7.tar.bz2 cryptography-d259ee51abae5a35e34f16ad74bfb1c62aa433d7.zip

Polishes builder documentation,

Diffstat (limited to 'src')

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from __future__ import (absolute_import, print_function, division)
import os
import select
import socket
import sys
import threading
import time
import traceback

import binascii

from typing import Optional  # noqa

from netlib import strutils
from six.moves import range

import certifi
from backports import ssl_match_hostname
import six
import OpenSSL
from OpenSSL import SSL

from netlib import certutils
from netlib import version_check
from netlib import basetypes
from netlib import exceptions
from netlib import basethread

# This is a rather hackish way to make sure that
# the latest version of pyOpenSSL is actually installed.
version_check.check_pyopenssl_version()

if six.PY2:
    socket_fileobject = socket._fileobject
else:
    socket_fileobject = socket.SocketIO

EINTR = 4
if os.environ.get("NO_ALPN"):
    HAS_ALPN = False
else:
    HAS_ALPN = SSL._lib.Cryptography_HAS_ALPN

# To enable all SSL methods use: SSLv23
# then add options to disable certain methods
# https://bugs.launchpad.net/pyopenssl/+bug/1020632/comments/3
SSL_BASIC_OPTIONS = (
    SSL.OP_CIPHER_SERVER_PREFERENCE
)
if hasattr(SSL, "OP_NO_COMPRESSION"):
    SSL_BASIC_OPTIONS |= SSL.OP_NO_COMPRESSION

SSL_DEFAULT_METHOD = SSL.SSLv23_METHOD
SSL_DEFAULT_OPTIONS = (
    SSL.OP_NO_SSLv2 |
    SSL.OP_NO_SSLv3 |
    SSL_BASIC_OPTIONS
)
if hasattr(SSL, "OP_NO_COMPRESSION"):
    SSL_DEFAULT_OPTIONS |= SSL.OP_NO_COMPRESSION

"""
Map a reasonable SSL version specification into the format OpenSSL expects.
Don't ask...
https://bugs.launchpad.net/pyopenssl/+bug/1020632/comments/3
"""
sslversion_choices = {
    "all": (SSL.SSLv23_METHOD, SSL_BASIC_OPTIONS),
    # SSLv23_METHOD + NO_SSLv2 + NO_SSLv3 == TLS 1.0+
    # TLSv1_METHOD would be TLS 1.0 only
    "secure": (SSL.SSLv23_METHOD, (SSL.OP_NO_SSLv2 | SSL.OP_NO_SSLv3 | SSL_BASIC_OPTIONS)),
    "SSLv2": (SSL.SSLv2_METHOD, SSL_BASIC_OPTIONS),
    "SSLv3": (SSL.SSLv3_METHOD, SSL_BASIC_OPTIONS),
    "TLSv1": (SSL.TLSv1_METHOD, SSL_BASIC_OPTIONS),
    "TLSv1_1": (SSL.TLSv1_1_METHOD, SSL_BASIC_OPTIONS),
    "TLSv1_2": (SSL.TLSv1_2_METHOD, SSL_BASIC_OPTIONS),
}


class SSLKeyLogger(object):

    def __init__(self, filename):
        self.filename = filename
        self.f = None
        self.lock = threading.Lock()

    # required for functools.wraps, which pyOpenSSL uses.
    __name__ = "SSLKeyLogger"

    def __call__(self, connection, where, ret):
        if where == SSL.SSL_CB_HANDSHAKE_DONE and ret == 1:
            with self.lock:
                if not self.f:
                    d = os.path.dirname(self.filename)
                    if not os.path.isdir(d):
                        os.makedirs(d)
                    self.f = open(self.filename, "ab")
                    self.f.write(b"\r\n")
                client_random = binascii.hexlify(connection.client_random())
                masterkey = binascii.hexlify(connection.master_key())
                self.f.write(b"CLIENT_RANDOM %s %s\r\n" % (client_random, masterkey))
                self.f.flush()

    def close(self):
        with self.lock:
            if self.f:
                self.f.close()

    @staticmethod
    def create_logfun(filename):
        if filename:
            return SSLKeyLogger(filename)
        return False

log_ssl_key = SSLKeyLogger.create_logfun(
    os.getenv("MITMPROXY_SSLKEYLOGFILE") or os.getenv("SSLKEYLOGFILE"))


class _FileLike(object):
    BLOCKSIZE = 1024 * 32

    def __init__(self, o):
        self.o = o
        self._log = None
        self.first_byte_timestamp = None

    def set_descriptor(self, o):
        self.o = o

    def __getattr__(self, attr):
        return getattr(self.o, attr)

    def start_log(self):
        """
            Starts or resets the log.

            This will store all bytes read or written.
        """
        self._log = []

    def stop_log(self):
        """
            Stops the log.
        """
        self._log = None

    def is_logging(self):
        return self._log is not None

    def get_log(self):
        """
            Returns the log as a string.
        """
        if not self.is_logging():
            raise ValueError("Not logging!")
        return b"".join(self._log)

    def add_log(self, v):
        if self.is_logging():
            self._log.append(v)

    def reset_timestamps(self):
        self.first_byte_timestamp = None


class Writer(_FileLike):

    def flush(self):
        """
            May raise exceptions.TcpDisconnect
        """
        if hasattr(self.o, "flush"):
            try:
                self.o.flush()
            except (socket.error, IOError) as v:
                raise exceptions.TcpDisconnect(str(v))

    def write(self, v):
        """
            May raise exceptions.TcpDisconnect
        """
        if v:
            self.first_byte_timestamp = self.first_byte_timestamp or time.time()
            try:
                if hasattr(self.o, "sendall"):
                    self.add_log(v)
                    return self.o.sendall(v)
                else:
                    r = self.o.write(v)
                    self.add_log(v[:r])
                    return r
            except (SSL.Error, socket.error) as e:
                raise exceptions.TcpDisconnect(str(e))


class Reader(_FileLike):

    def read(self, length):
        """
            If length is -1, we read until connection closes.
        """
        result = b''
        start = time.time()
        while length == -1 or length > 0:
            if length == -1 or length > self.BLOCKSIZE:
                rlen = self.BLOCKSIZE
            else:
                rlen = length
            try:
                data = self.o.read(rlen)
            except SSL.ZeroReturnError:
                # TLS connection was shut down cleanly
                break
            except (SSL.WantWriteError, SSL.WantReadError):
                # From the OpenSSL docs:
                # If the underlying BIO is non-blocking, SSL_read() will also return when the
                # underlying BIO could not satisfy the needs of SSL_read() to continue the
                # operation. In this case a call to SSL_get_error with the return value of
                # SSL_read() will yield SSL_ERROR_WANT_READ or SSL_ERROR_WANT_WRITE.
                if (time.time() - start) < self.o.gettimeout():
                    time.sleep(0.1)
                    continue
                else:
                    raise exceptions.TcpTimeout()
            except socket.timeout:
                raise exceptions.TcpTimeout()
            except socket.error as e:
                raise exceptions.TcpDisconnect(str(e))
            except SSL.SysCallError as e:
                if e.args == (-1, 'Unexpected EOF'):
                    break
                raise exceptions.TlsException(str(e))
            except SSL.Error as e:
                raise exceptions.TlsException(str(e))
            self.first_byte_timestamp = self.first_byte_timestamp or time.time()
            if not data:
                break
            result += data
            if length != -1:
                length -= len(data)
        self.add_log(result)
        return result

    def readline(self, size=None):
        result = b''
        bytes_read = 0
        while True:
            if size is not None and bytes_read >= size:
                break
            ch = self.read(1)
            bytes_read += 1
            if not ch:
                break
            else:
                result += ch
                if ch == b'\n':
                    break
        return result

    def safe_read(self, length):
        """
            Like .read, but is guaranteed to either return length bytes, or
            raise an exception.
        """
        result = self.read(length)
        if length != -1 and len(result) != length:
            if not result:
                raise exceptions.TcpDisconnect()
            else:
                raise exceptions.TcpReadIncomplete(
                    "Expected %s bytes, got %s" % (length, len(result))
                )
        return result

    def peek(self, length):
        """
        Tries to peek into the underlying file object.

        Returns:
            Up to the next N bytes if peeking is successful.

        Raises:
            exceptions.TcpException if there was an error with the socket
            TlsException if there was an error with pyOpenSSL.
            NotImplementedError if the underlying file object is not a [pyOpenSSL] socket
        """
        if isinstance(self.o, socket_fileobject):
            try:
                return self.o._sock.recv(length, socket.MSG_PEEK)
            except socket.error as e:
                raise exceptions.TcpException(repr(e))
        elif isinstance(self.o, SSL.Connection):
            try:
                return self.o.recv(length, socket.MSG_PEEK)
            except SSL.Error as e:
                six.reraise(exceptions.TlsException, exceptions.TlsException(str(e)), sys.exc_info()[2])
        else:
            raise NotImplementedError("Can only peek into (pyOpenSSL) sockets")


class Address(basetypes.Serializable):

    """
        This class wraps an IPv4/IPv6 tuple to provide named attributes and
        ipv6 information.
    """

    def __init__(self, address, use_ipv6=False):
        self.address = tuple(address)
        self.use_ipv6 = use_ipv6

    def get_state(self):
        return {
            "address": self.address,
            "use_ipv6": self.use_ipv6
        }

    def set_state(self, state):
        self.address = state["address"]
        self.use_ipv6 = state["use_ipv6"]

    @classmethod
    def from_state(cls, state):
        return Address(**state)

    @classmethod
    def wrap(cls, t):
        if isinstance(t, cls):
            return t
        else:
            return cls(t)

    def __call__(self):
        return self.address

    @property
    def host(self):
        return self.address[0]

    @property
    def port(self):
        return self.address[1]

    @property
    def use_ipv6(self):
        return self.family == socket.AF_INET6

    @use_ipv6.setter
    def use_ipv6(self, b):
        self.family = socket.AF_INET6 if b else socket.AF_INET

    def __repr__(self):
        return "{}:{}".format(self.host, self.port)

    def __eq__(self, other):
        if not other:
            return False
        other = Address.wrap(other)
        return (self.address, self.family) == (other.address, other.family)

    def __ne__(self, other):
        return not self.__eq__(other)

    def __hash__(self):
        return hash(self.address) ^ 42  # different hash than the tuple alone.


def ssl_read_select(rlist, timeout):
    """
    This is a wrapper around select.select() which also works for SSL.Connections
    by taking ssl_connection.pending() into account.

    Caveats:
        If .pending() > 0 for any of the connections in rlist, we avoid the select syscall
        and **will not include any other connections which may or may not be ready**.

    Args:
        rlist: wait until ready for reading

    Returns:
        subset of rlist which is ready for reading.
    """
    return [
        conn for conn in rlist
        if isinstance(conn, SSL.Connection) and conn.pending() > 0
    ] or select.select(rlist, (), (), timeout)[0]


def close_socket(sock):
    """
    Does a hard close of a socket, without emitting a RST.
    """
    try:
        # We already indicate that we close our end.
        # may raise "Transport endpoint is not connected" on Linux
        sock.shutdown(socket.SHUT_WR)

        # Section 4.2.2.13 of RFC 1122 tells us that a close() with any pending
        # readable data could lead to an immediate RST being sent (which is the
        # case on Windows).
        # http://ia600609.us.archive.org/22/items/TheUltimateSo_lingerPageOrWhyIsMyTcpNotReliable/the-ultimate-so_linger-page-or-why-is-my-tcp-not-reliable.html
        #
        # This in turn results in the following issue: If we send an error page
        # to the client and then close the socket, the RST may be received by
        # the client before the error page and the users sees a connection
        # error rather than the error page. Thus, we try to empty the read
        # buffer on Windows first. (see
        # https://github.com/mitmproxy/mitmproxy/issues/527#issuecomment-93782988)
        #

        if os.name == "nt":  # pragma: no cover
            # We cannot rely on the shutdown()-followed-by-read()-eof technique
            # proposed by the page above: Some remote machines just don't send
            # a TCP FIN, which would leave us in the unfortunate situation that
            # recv() would block infinitely. As a workaround, we set a timeout
            # here even if we are in blocking mode.
            sock.settimeout(sock.gettimeout() or 20)

            # limit at a megabyte so that we don't read infinitely
            for _ in range(1024 ** 3 // 4096):
                # may raise a timeout/disconnect exception.
                if not sock.recv(4096):
                    break

        # Now we can close the other half as well.
        sock.shutdown(socket.SHUT_RD)

    except socket.error:
        pass

    sock.close()


class _Connection(object):

    rbufsize = -1
    wbufsize = -1

    def _makefile(self):
        """
        Set up .rfile and .wfile attributes from .connection
        """
        # Ideally, we would use the Buffered IO in Python 3 by default.
        # Unfortunately, the implementation of .peek() is broken for n>1 bytes,
        # as it may just return what's left in the buffer and not all the bytes we want.
        # As a workaround, we just use unbuffered sockets directly.
        # https://mail.python.org/pipermail/python-dev/2009-June/089986.html
        if six.PY2:
            self.rfile = Reader(self.connection.makefile('rb', self.rbufsize))
            self.wfile = Writer(self.connection.makefile('wb', self.wbufsize))
        else:
            self.rfile = Reader(socket.SocketIO(self.connection, "rb"))
            self.wfile = Writer(socket.SocketIO(self.connection, "wb"))

    def __init__(self, connection):
        if connection:
            self.connection = connection
            self.ip_address = Address(connection.getpeername())
            self._makefile()
        else:
            self.connection = None
            self.ip_address = None
            self.rfile = None
            self.wfile = None

        self.ssl_established = False
        self.finished = False

    def get_current_cipher(self):
        if not self.ssl_established:
            return None

        name = self.connection.get_cipher_name()
        bits = self.connection.get_cipher_bits()
        version = self.connection.get_cipher_version()
        return name, bits, version

    def finish(self):
        self.finished = True
        # If we have an SSL connection, wfile.close == connection.close
        # (We call _FileLike.set_descriptor(conn))
        # Closing the socket is not our task, therefore we don't call close
        # then.
        if not isinstance(self.connection, SSL.Connection):
            if not getattr(self.wfile, "closed", False):
                try:
                    self.wfile.flush()
                    self.wfile.close()
                except exceptions.TcpDisconnect:
                    pass

            self.rfile.close()
        else:
            try:
                self.connection.shutdown()
            except SSL.Error:
                pass

    def _create_ssl_context(self,
                            method=SSL_DEFAULT_METHOD,
                            options=SSL_DEFAULT_OPTIONS,
                            verify_options=SSL.VERIFY_NONE,
                            ca_path=None,
                            ca_pemfile=None,
                            cipher_list=None,
                            alpn_protos=None,
                            alpn_select=None,
                            alpn_select_callback=None,
                            sni=None,
                            ):
        """
        Creates an SSL Context.

        :param method: One of SSLv2_METHOD, SSLv3_METHOD, SSLv23_METHOD, TLSv1_METHOD, TLSv1_1_METHOD, or TLSv1_2_METHOD
        :param options: A bit field consisting of OpenSSL.SSL.OP_* values
        :param verify_options: A bit field consisting of OpenSSL.SSL.VERIFY_* values
        :param ca_path: Path to a directory of trusted CA certificates prepared using the c_rehash tool
        :param ca_pemfile: Path to a PEM formatted trusted CA certificate
        :param cipher_list: A textual OpenSSL cipher list, see https://www.openssl.org/docs/apps/ciphers.html
        :rtype : SSL.Context
        """
        context = SSL.Context(method)
        # Options (NO_SSLv2/3)
        if options is not None:
            context.set_options(options)

        # Verify Options (NONE/PEER and trusted CAs)
        if verify_options is not None:
            def verify_cert(conn, x509, errno, err_depth, is_cert_verified):
                if not is_cert_verified:
                    self.ssl_verification_error = exceptions.InvalidCertificateException(
                        "Certificate Verification Error for {}: {} (errno: {}, depth: {})".format(
                            sni,
                            strutils.native(SSL._ffi.string(SSL._lib.X509_verify_cert_error_string(errno)), "utf8"),
                            errno,
                            err_depth
                        )
                    )
                return is_cert_verified

            context.set_verify(verify_options, verify_cert)
            if ca_path is None and ca_pemfile is None:
                ca_pemfile = certifi.where()
            context.load_verify_locations(ca_pemfile, ca_path)

        # Workaround for
        # https://github.com/pyca/pyopenssl/issues/190
        # https://github.com/mitmproxy/mitmproxy/issues/472
        # Options already set before are not cleared.
        context.set_mode(SSL._lib.SSL_MODE_AUTO_RETRY)


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