M2Crypto.BIO — M2Crypto documentation

# Source code for M2Crypto.BIO

    from __future__ import absolute_import

    """M2Crypto wrapper for OpenSSL BIO API.

    Copyright (c) 1999-2004 Ng Pheng Siong. All rights reserved."""

    import io
    import logging
    from typing import Any, AnyStr, Callable, Iterable, Optional, Union  # noqa

    from M2Crypto import m2, six

    log = logging.getLogger('BIO')

    class BIOError(ValueError):
        pass

    m2.bio_init(BIOError)

    class BIO(object):
        """Abstract object interface to the BIO API."""

        m2_bio_free = m2.bio_free

        def __init__(self, bio=None, _pyfree=0, _close_cb=None):
            # type: (Optional[BIO], int, Optional[Callable]) -> None
            self.bio = bio
            self._pyfree = _pyfree
            self._close_cb = _close_cb
            self.closed = 0
            self.write_closed = 0

        def __del__(self):
            if self._pyfree:
                self.m2_bio_free(self.bio)

        def _ptr(self):
            return self.bio

        # Deprecated.
        bio_ptr = _ptr

        def fileno(self):
            # type: () -> int
            return m2.bio_get_fd(self.bio)

        def readable(self):
            # type: () -> bool
            return not self.closed

        def read(self, size=None):
            # type: (int) -> Union[bytes, bytearray]
            if not self.readable():
                raise IOError('cannot read')
            if size is None:
                buf = bytearray()
                while 1:
                    data = m2.bio_read(self.bio, 4096)
                    if not data:
                        break
                    buf += data
                return buf
            elif size == 0:
                return b''
            elif size < 0:
                raise ValueError('read count is negative')
            else:
                return bytes(m2.bio_read(self.bio, size))

        def readline(self, size=4096):
            # type: (int) -> bytes
            if not self.readable():
                raise IOError('cannot read')
            buf = m2.bio_gets(self.bio, size)
            buf = '' if buf is None else buf
            return six.ensure_binary(buf)

        def readlines(self, sizehint='ignored'):
            # type: (Union[AnyStr, int]) -> Iterable[bytes]
            if not self.readable():
                raise IOError('cannot read')
            lines = []
            while 1:
                buf = m2.bio_gets(self.bio, 4096)
                if buf is None:
                    break
                lines.append(six.ensure_binary(buf))
            return lines

        def writeable(self):
            # type: () -> bool
            return (not self.closed) and (not self.write_closed)

        def write(self, data):
            # type: (AnyStr) -> int
            """Write data to BIO.

            :return: either data written, or [0, -1] for nothing written,
                     -2 not implemented
            """
            if not self.writeable():
                raise IOError('cannot write')
            if isinstance(data, six.text_type):
                data = data.encode('utf8')
            return m2.bio_write(self.bio, data)

        def write_close(self):
            # type: () -> None
            self.write_closed = 1

        def flush(self):
            # type: () -> None
            """Flush the buffers.

            :return: 1 for success, and 0 or -1 for failure
            """
            m2.bio_flush(self.bio)

        def reset(self):
            # type: () -> int
            """Set the bio to its initial state.

            :return: 1 for success, and 0 or -1 for failure
            """
            return m2.bio_reset(self.bio)

        def close(self):
            # type: () -> None
            self.closed = 1
            if self._close_cb:
                self._close_cb()

        def should_retry(self):
            # type: () -> int
            """
            Can the call be attempted again, or was there an error
            ie do_handshake

            """
            return m2.bio_should_retry(self.bio)

        def should_read(self):
            # type: () -> int
            """Should we read more data?"""

            return m2.bio_should_read(self.bio)

        def should_write(self):
            # type: () -> int
            """Should we write more data?"""
            return m2.bio_should_write(self.bio)

        def tell(self):
            """Return the current offset."""
            return m2.bio_tell(self.bio)

        def seek(self, off):
            """Seek to the specified absolute offset."""
            return m2.bio_seek(self.bio, off)

        def __enter__(self):
            return self

        def __exit__(self, *args):
            # type: (*Any) -> int
            self.close()

    class MemoryBuffer(BIO):
        """Object interface to BIO_s_mem.

        Empirical testing suggests that this class performs less well than
        cStringIO, because cStringIO is implemented in C, whereas this class
        is implemented in Python. Thus, the recommended practice is to use
        cStringIO for regular work and convert said cStringIO object to
        a MemoryBuffer object only when necessary.
        """

        def __init__(self, data=None):
            # type: (Optional[bytes]) -> None
            super(MemoryBuffer, self).__init__(self)
            if data is not None and not isinstance(data, bytes):
                raise TypeError(
                    "data must be bytes or None, not %s" % (type(data).__name__, ))
            self.bio = m2.bio_new(m2.bio_s_mem())
            self._pyfree = 1
            if data is not None:
                m2.bio_write(self.bio, data)

        def __len__(self):
            # type: () -> int
            return m2.bio_ctrl_pending(self.bio)

        def read(self, size=0):
            # type: (int) -> bytes
            if not self.readable():
                raise IOError('cannot read')
            if size:
                return m2.bio_read(self.bio, size)
            else:
                return m2.bio_read(self.bio, m2.bio_ctrl_pending(self.bio))

        # Backwards-compatibility.
        getvalue = read_all = read

        def write_close(self):
            # type: () -> None
            super(MemoryBuffer, self).write_close()
            m2.bio_set_mem_eof_return(self.bio, 0)

        close = write_close

    class File(BIO):
        """Object interface to BIO_s_pyfd.

        This class interfaces Python to OpenSSL functions that expect BIO. For
        general file manipulation in Python, use Python's builtin file object.
        """

        def __init__(self, pyfile, close_pyfile=1, mode='rb'):
            # type: (Union[io.BytesIO, AnyStr], int, AnyStr) -> None
            super(File, self).__init__(self, _pyfree=1)

            if isinstance(pyfile, six.string_types):
                pyfile = open(pyfile, mode)

            # This is for downward compatibility, but I don't think, that it is
            # good practice to have two handles for the same file. Whats about
            # concurrent write access? Last write, last wins? Especially since Py3
            # has its own buffer management. See:
            #
            #  https://docs.python.org/3.3/c-api/file.html
            #
            pyfile.flush()
            self.fname = pyfile.name
            self.pyfile = pyfile
            # Be wary of https://github.com/openssl/openssl/pull/1925
            # BIO_new_fd is NEVER to be used before OpenSSL 1.1.1
            if hasattr(m2, "bio_new_pyfd"):
                self.bio = m2.bio_new_pyfd(pyfile.fileno(), m2.bio_noclose)
            else:
                self.bio = m2.bio_new_pyfile(pyfile, m2.bio_noclose)

            self.close_pyfile = close_pyfile
            self.closed = False

        def flush(self):
            # type: () -> None
            super(File, self).flush()
            self.pyfile.flush()

        def close(self):
            # type: () -> None
            self.flush()
            super(File, self).close()
            if self.close_pyfile:
                self.pyfile.close()

        def reset(self):
            # type: () -> int
            """Set the bio to its initial state.

            :return: 0 for success, and -1 for failure
            """
            return super(File, self).reset()

        def __del__(self):
            if not self.closed:
                m2.bio_free(self.bio)

    def openfile(filename, mode='rb'):
        # type: (AnyStr, AnyStr) -> File
        try:
            f = open(filename, mode)
        except IOError as ex:
            raise BIOError(ex.args)

        return File(f)

    class IOBuffer(BIO):
        """Object interface to BIO_f_buffer.

        Its principal function is to be BIO_push()'ed on top of a BIO_f_ssl, so
        that makefile() of said underlying SSL socket works.
        """

        m2_bio_pop = m2.bio_pop
        m2_bio_free = m2.bio_free

        def __init__(self, under_bio, mode='rwb', _pyfree=1):
            # type: (BIO, str, int) -> None
            super(IOBuffer, self).__init__(self, _pyfree=_pyfree)
            self.io = m2.bio_new(m2.bio_f_buffer())
            self.bio = m2.bio_push(self.io, under_bio._ptr())
            # This reference keeps the underlying BIO alive while we're not closed.
            self._under_bio = under_bio
            if 'w' in mode:
                self.write_closed = 0
            else:
                self.write_closed = 1

        def __del__(self):
            # type: () -> None
            if getattr(self, '_pyfree', 0):
                self.m2_bio_pop(self.bio)
            self.m2_bio_free(self.io)

        def close(self):
            # type: () -> None
            BIO.close(self)

    class CipherStream(BIO):
        """Object interface to BIO_f_cipher."""

        SALT_LEN = m2.PKCS5_SALT_LEN

        m2_bio_pop = m2.bio_pop
        m2_bio_free = m2.bio_free

        def __init__(self, obio):
            # type: (BIO) -> None
            super(CipherStream, self).__init__(self, _pyfree=1)
            self.obio = obio
            self.bio = m2.bio_new(m2.bio_f_cipher())
            self.closed = 0

        def __del__(self):
            # type: () -> None
            if not getattr(self, 'closed', 1):
                self.close()

        def close(self):
            # type: () -> None
            self.m2_bio_pop(self.bio)
            self.m2_bio_free(self.bio)
            self.closed = 1

        def write_close(self):
            # type: () -> None
            self.obio.write_close()

        def set_cipher(self, algo, key, iv, op):
            # type: (str, AnyStr, AnyStr, int) -> None
            cipher = getattr(m2, algo, None)
            if cipher is None:
                raise ValueError('unknown cipher', algo)
            else:
                if not isinstance(key, bytes):
                    key = key.encode('utf8')
                if not isinstance(iv, bytes):
                    iv = iv.encode('utf8')
            m2.bio_set_cipher(self.bio, cipher(), key, iv, int(op))
            m2.bio_push(self.bio, self.obio._ptr())

    class SSLBio(BIO):
        """Object interface to BIO_f_ssl."""

        def __init__(self, _pyfree=1):
            # type: (int) -> None
            super(SSLBio, self).__init__(self, _pyfree=_pyfree)
            self.bio = m2.bio_new(m2.bio_f_ssl())
            self.closed = 0

        def set_ssl(self, conn, close_flag=m2.bio_noclose):
            ## type: (Connection, int) -> None
            """
            Sets the bio to the SSL pointer which is
            contained in the connection object.
            """
            self._pyfree = 0
            m2.bio_set_ssl(self.bio, conn.ssl, close_flag)
            if close_flag == m2.bio_noclose:
                conn.set_ssl_close_flag(m2.bio_close)

        def do_handshake(self):
            # type: () -> int
            """Do the handshake.

            Return 1 if the handshake completes
            Return 0 or a negative number if there is a problem
            """
            return m2.bio_do_handshake(self.bio)