.. _openssl-ssl: :py:mod:`SSL` --- An interface to the SSL-specific parts of OpenSSL =================================================================== .. py:module:: OpenSSL.SSL :synopsis: An interface to the SSL-specific parts of OpenSSL This module handles things specific to SSL. There are two objects defined: Context, Connection. .. py:data:: SSLv2_METHOD SSLv3_METHOD SSLv23_METHOD TLSv1_METHOD TLSv1_1_METHOD TLSv1_2_METHOD These constants represent the different SSL methods to use when creating a context object. If the underlying OpenSSL build is missing support for any of these protocols, constructing a :py:class:`Context` using the corresponding :py:const:`*_METHOD` will raise an exception. .. py:data:: VERIFY_NONE VERIFY_PEER VERIFY_FAIL_IF_NO_PEER_CERT These constants represent the verification mode used by the Context object's :py:meth:`set_verify` method. .. py:data:: FILETYPE_PEM FILETYPE_ASN1 File type constants used with the :py:meth:`use_certificate_file` and :py:meth:`use_privatekey_file` methods of Context objects. .. py:data:: OP_SINGLE_DH_USE OP_SINGLE_ECDH_USE Constants used with :py:meth:`set_options` of Context objects. When these options are used, a new key will always be created when using ephemeral (Elliptic curve) Diffie-Hellman. .. py:data:: OP_EPHEMERAL_RSA Constant used with :py:meth:`set_options` of Context objects. When this option is used, ephemeral RSA keys will always be used when doing RSA operations. .. py:data:: OP_NO_TICKET Constant used with :py:meth:`set_options` of Context objects. When this option is used, the session ticket extension will not be used. .. py:data:: OP_NO_COMPRESSION Constant used with :py:meth:`set_options` of Context objects. When this option is used, compression will not be used. .. py:data:: OP_NO_SSLv2 OP_NO_SSLv3 OP_NO_TLSv1 OP_NO_TLSv1_1 OP_NO_TLSv1_2 Constants used with :py:meth:`set_options` of Context objects. Each of these options disables one version of the SSL/TLS protocol. This is interesting if you're using e.g. :py:const:`SSLv23_METHOD` to get an SSLv2-compatible handshake, but don't want to use SSLv2. If the underlying OpenSSL build is missing support for any of these protocols, the :py:const:`OP_NO_*` constant may be undefined. .. py:data:: SSLEAY_VERSION SSLEAY_CFLAGS SSLEAY_BUILT_ON SSLEAY_PLATFORM SSLEAY_DIR Constants used with :py:meth:`SSLeay_version` to specify what OpenSSL version information to retrieve. See the man page for the :py:func:`SSLeay_version` C API for details. .. py:data:: SESS_CACHE_OFF SESS_CACHE_CLIENT SESS_CACHE_SERVER SESS_CACHE_BOTH SESS_CACHE_NO_AUTO_CLEAR SESS_CACHE_NO_INTERNAL_LOOKUP SESS_CACHE_NO_INTERNAL_STORE SESS_CACHE_NO_INTERNAL Constants used with :py:meth:`Context.set_session_cache_mode` to specify the behavior of the session cache and potential session reuse. See the man page for the :py:func:`SSL_CTX_set_session_cache_mode` C API for details. .. versionadded:: 0.14 .. py:data:: OPENSSL_VERSION_NUMBER An integer giving the version number of the OpenSSL library used to build this version of pyOpenSSL. See the man page for the :py:func:`SSLeay_version` C API for details. .. autofunction:: SSLeay_version .. py:data:: ContextType See :py:class:`Context`. .. autoclass:: Context .. autoclass:: Session .. py:data:: ConnectionType See :py:class:`Connection`. .. py:class:: Connection(context, socket) A class representing SSL connections. *context* should be an instance of :py:class:`Context` and *socket* should be a socket [#connection-context-socket]_ object. *socket* may be *None*; in this case, the Connection is created with a memory BIO: see the :py:meth:`bio_read`, :py:meth:`bio_write`, and :py:meth:`bio_shutdown` methods. .. py:exception:: Error This exception is used as a base class for the other SSL-related exceptions, but may also be raised directly. Whenever this exception is raised directly, it has a list of error messages from the OpenSSL error queue, where each item is a tuple *(lib, function, reason)*. Here *lib*, *function* and *reason* are all strings, describing where and what the problem is. See :manpage:`err(3)` for more information. .. py:exception:: ZeroReturnError This exception matches the error return code :py:data:`SSL_ERROR_ZERO_RETURN`, and is raised when the SSL Connection has been closed. In SSL 3.0 and TLS 1.0, this only occurs if a closure alert has occurred in the protocol, i.e. the connection has been closed cleanly. Note that this does not necessarily mean that the transport layer (e.g. a socket) has been closed. It may seem a little strange that this is an exception, but it does match an :py:data:`SSL_ERROR` code, and is very convenient. .. py:exception:: WantReadError The operation did not complete; the same I/O method should be called again later, with the same arguments. Any I/O method can lead to this since new handshakes can occur at any time. The wanted read is for **dirty** data sent over the network, not the **clean** data inside the tunnel. For a socket based SSL connection, **read** means data coming at us over the network. Until that read succeeds, the attempted :py:meth:`OpenSSL.SSL.Connection.recv`, :py:meth:`OpenSSL.SSL.Connection.send`, or :py:meth:`OpenSSL.SSL.Connection.do_handshake` is prevented or incomplete. You probably want to :py:meth:`select()` on the socket before trying again. .. py:exception:: WantWriteError See :py:exc:`WantReadError`. The socket send buffer may be too full to write more data. .. py:exception:: WantX509LookupError The operation did not complete because an application callback has asked to be called again. The I/O method should be called again later, with the same arguments. .. note:: This won't occur in this version, as there are no such callbacks in this version. .. py:exception:: SysCallError The :py:exc:`SysCallError` occurs when there's an I/O error and OpenSSL's error queue does not contain any information. This can mean two things: An error in the transport protocol, or an end of file that violates the protocol. The parameter to the exception is always a pair *(errnum, errstr)*. .. _openssl-context: Context objects --------------- Context objects have the following methods: .. autoclass:: OpenSSL.SSL.Context :members: .. _openssl-session: Session objects --------------- Session objects have no methods. .. _openssl-connection: Connection objects ------------------ Connection objects have the following methods: .. py:method:: Connection.accept() Call the :py:meth:`accept` method of the underlying socket and set up SSL on the returned socket, using the Context object supplied to this Connection object at creation. Returns a pair *(conn, address)*. where *conn* is the new Connection object created, and *address* is as returned by the socket's :py:meth:`accept`. .. py:method:: Connection.bind(address) Call the :py:meth:`bind` method of the underlying socket. .. py:method:: Connection.close() Call the :py:meth:`close` method of the underlying socket. Note: If you want correct SSL closure, you need to call the :py:meth:`shutdown` method first. .. py:method:: Connection.connect(address) Call the :py:meth:`connect` method of the underlying socket and set up SSL on the socket, using the Context object supplied to this Connection object at creation. .. py:method:: Connection.connect_ex(address) Call the :py:meth:`connect_ex` method of the underlying socket and set up SSL on the socket, using the Context object supplied to this Connection object at creation. Note that if the :py:meth:`connect_ex` method of the socket doesn't return 0, SSL won't be initialized. .. py:method:: Connection.do_handshake() Perform an SSL handshake (usually called after :py:meth:`renegotiate` or one of :py:meth:`set_accept_state` or :py:meth:`set_accept_state`). This can raise the same exceptions as :py:meth:`send` and :py:meth:`recv`. .. py:method:: Connection.fileno() Retrieve the file descriptor number for the underlying socket. .. py:method:: Connection.listen(backlog) Call the :py:meth:`listen` method of the underlying socket. .. py:method:: Connection.get_app_data() Retrieve application data as set by :py:meth:`set_app_data`. .. automethod:: Connection.get_cipher_list .. py:method:: Connection.get_protocol_version() Retrieve the version of the SSL or TLS protocol used by the Connection. For example, it will return ``0x769`` for connections made over TLS version 1. .. py:method:: Connection.get_protocol_version_name() Retrieve the version of the SSL or TLS protocol used by the Connection as a unicode string. For example, it will return ``TLSv1`` for connections made over TLS version 1, or ``Unknown`` for connections that were not successfully established. .. py:method:: Connection.get_client_ca_list() Retrieve the list of preferred client certificate issuers sent by the server as :py:class:`OpenSSL.crypto.X509Name` objects. If this is a client :py:class:`Connection`, the list will be empty until the connection with the server is established. If this is a server :py:class:`Connection`, return the list of certificate authorities that will be sent or has been sent to the client, as controlled by this :py:class:`Connection`'s :py:class:`Context`. .. versionadded:: 0.10 .. py:method:: Connection.get_context() Retrieve the Context object associated with this Connection. .. py:method:: Connection.set_context(context) Specify a replacement Context object for this Connection. .. py:method:: Connection.get_peer_certificate() Retrieve the other side's certificate (if any) .. py:method:: Connection.get_peer_cert_chain() Retrieve the tuple of the other side's certificate chain (if any) .. py:method:: Connection.getpeername() Call the :py:meth:`getpeername` method of the underlying socket. .. py:method:: Connection.getsockname() Call the :py:meth:`getsockname` method of the underlying socket. .. py:method:: Connection.getsockopt(level, optname[, buflen]) Call the :py:meth:`getsockopt` method of the underlying socket. .. py:method:: Connection.pending() Retrieve the number of bytes that can be safely read from the SSL buffer (**not** the underlying transport buffer). .. py:method:: Connection.recv(bufsize[, flags]) Receive data from the Connection. The return value is a string representing the data received. The maximum amount of data to be received at once, is specified by *bufsize*. The only supported flag is ``MSG_PEEK``, all other flags are ignored. .. py:method:: Connection.recv_into(buffer[, nbytes[, flags]]) Receive data from the Connection and copy it directly into the provided buffer. The return value is the number of bytes read from the connection. The maximum amount of data to be received at once is specified by *nbytes*. The only supported flag is ``MSG_PEEK``, all other flags are ignored. .. py:method:: Connection.bio_write(bytes) If the Connection was created with a memory BIO, this method can be used to add bytes to the read end of that memory BIO. The Connection can then read the bytes (for example, in response to a call to :py:meth:`recv`). .. automethod:: Connection.renegotiate .. automethod:: Connection.renegotiate_pending .. automethod:: Connection.total_renegotiations .. py:method:: Connection.send(string) Send the *string* data to the Connection. .. py:method:: Connection.bio_read(bufsize) If the Connection was created with a memory BIO, this method can be used to read bytes from the write end of that memory BIO. Many Connection methods will add bytes which must be read in this manner or the buffer will eventually fill up and the Connection will be able to take no further actions. .. py:method:: Connection.sendall(string) Send all of the *string* data to the Connection. This calls :py:meth:`send` repeatedly until all data is sent. If an error occurs, it's impossible to tell how much data has been sent. .. py:method:: Connection.set_accept_state() Set the connection to work in server mode. The handshake will be handled automatically by read/write. .. py:method:: Connection.set_app_data(data) Associate *data* with this Connection object. *data* can be retrieved later using the :py:meth:`get_app_data` method. .. py:method:: Connection.set_connect_state() Set the connection to work in client mode. The handshake will be handled automatically by read/write. .. py:method:: Connection.setblocking(flag) Call the :py:meth:`setblocking` method of the underlying socket. .. py:method:: Connection.setsockopt(level, optname, value) Call the :py:meth:`setsockopt` method of the underlying socket. .. py:method:: Connection.shutdown() Send the shutdown message to the Connection. Returns true if the shutdown message exchange is completed and false otherwise (in which case you call :py:meth:`recv` or :py:meth:`send` when the connection becomes readable/writeable. .. py:method:: Connection.get_shutdown() Get the shutdown state of the Connection. Returns a bitvector of either or both of *SENT_SHUTDOWN* and *RECEIVED_SHUTDOWN*. .. py:method:: Connection.set_shutdown(state) Set the shutdown state of the Connection. *state* is a bitvector of either or both of *SENT_SHUTDOWN* and *RECEIVED_SHUTDOWN*. .. py:method:: Connection.sock_shutdown(how) Call the :py:meth:`shutdown` method of the underlying socket. .. py:method:: Connection.bio_shutdown() If the Connection was created with a memory BIO, this method can be used to indicate that *end of file* has been reached on the read end of that memory BIO. .. automethod:: Connection.get_state_string .. py:method:: Connection.client_random() Retrieve the random value used with the client hello message. .. py:method:: Connection.server_random() Retrieve the random value used with the server hello message. .. py:method:: Connection.master_key() Retrieve the value of the master key for this session. .. py:method:: Connection.want_read() Checks if more data has to be read from the transport layer to complete an operation. .. py:method:: Connection.want_write() Checks if there is data to write to the transport layer to complete an operation. .. py:method:: Connection.set_tlsext_host_name(name) Specify the byte string to send as the server name in the client hello message. .. versionadded:: 0.13 .. py:method:: Connection.get_servername() Get the value of the server name received in the client hello message. .. versionadded:: 0.13 .. py:method:: Connection.get_session() Get a :py:class:`Session` instance representing the SSL session in use by the connection, or :py:obj:`None` if there is no session. .. versionadded:: 0.14 .. py:method:: Connection.set_session(session) Set a new SSL session (using a :py:class:`Session` instance) to be used by the connection. .. versionadded:: 0.14 .. py:method:: Connection.get_finished() Obtain latest TLS Finished message that we sent, or :py:obj:`None` if handshake is not completed. .. versionadded:: 0.15 .. py:method:: Connection.get_peer_finished() Obtain latest TLS Finished message that we expected from peer, or :py:obj:`None` if handshake is not completed. .. versionadded:: 0.15 .. py:method:: Connection.get_cipher_name() Obtain the name of the currently used cipher. .. versionadded:: 0.15 .. py:method:: Connection.get_cipher_bits() Obtain the number of secret bits of the currently used cipher. .. versionadded:: 0.15 .. py:method:: Connection.get_cipher_version() Obtain the protocol name of the currently used cipher. .. versionadded:: 0.15 .. py:method:: Connection.get_next_proto_negotiated(): Get the protocol that was negotiated by Next Protocol Negotiation. Returns a bytestring of the protocol name. If no protocol has been negotiated yet, returns an empty string. .. versionadded:: 0.15 .. py:method:: Connection.set_alpn_protos(protos) Specify the protocols that the client is prepared to speak after the TLS connection has been negotiated using Application Layer Protocol Negotiation. *protos* should be a list of protocols that the client is offering, each as a bytestring. For example, ``[b'http/1.1', b'spdy/2']``. .. py:method:: Connection.get_alpn_proto_negotiated() Get the protocol that was negotiated by Application Layer Protocol Negotiation. Returns a bytestring of the protocol name. If no protocol has been negotiated yet, returns an empty string. .. Rubric:: Footnotes .. [#connection-context-socket] Actually, all that is required is an object that **behaves** like a socket, you could even use files, even though it'd be tricky to get the handshakes right!