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<H2><A NAME="SECTION000430000000000000000"> </A>
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3.3 <tt class="module">SSL</tt> -- An interface to the SSL-specific parts of OpenSSL
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This module handles things specific to SSL. There are two objects defined:
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<dl><dt><b><a name='l2h-129'><tt>SSLv2_METHOD</tt></a></b>
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<dt><b><a name='l2h-146'><tt>SSLv3_METHOD</tt></a></b><dd>
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<dt><b><a name='l2h-147'><tt>SSLv23_METHOD</tt></a></b><dd>
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<dt><b><a name='l2h-148'><tt>TLSv1_METHOD</tt></a></b><dd>
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These constants represent the different SSL methods to use when creating a
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<dl><dt><b><a name='l2h-130'><tt>VERIFY_NONE</tt></a></b>
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<dt><b><a name='l2h-149'><tt>VERIFY_PEER</tt></a></b><dd>
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<dt><b><a name='l2h-150'><tt>VERIFY_FAIL_IF_NO_PEER_CERT</tt></a></b><dd>
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These constants represent the verification mode used by the Context
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object's <tt class="method">set_verify</tt> method.
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<dl><dt><b><a name='l2h-131'><tt>FILETYPE_PEM</tt></a></b>
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<dt><b><a name='l2h-151'><tt>FILETYPE_ASN1</tt></a></b><dd>
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File type constants used with the <tt class="method">use_certificate_file</tt> and
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<tt class="method">use_privatekey_file</tt> methods of Context objects.
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<dl><dt><b><a name='l2h-132'><tt>OP_SINGLE_DH_USE</tt></a></b>
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<dt><b><a name='l2h-152'><tt>OP_EPHEMERAL_RSA</tt></a></b><dd>
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<dt><b><a name='l2h-153'><tt>OP_NO_SSLv2</tt></a></b><dd>
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<dt><b><a name='l2h-154'><tt>OP_NO_SSLv3</tt></a></b><dd>
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<dt><b><a name='l2h-155'><tt>OP_NO_TLSv1</tt></a></b><dd>
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Constants used with <tt class="method">set_options</tt> of Context objects.
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<tt class="constant">OP_SINGLE_DH_USE</tt> means to always create a new key when using ephemeral
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Diffie-Hellman. <tt class="constant">OP_EPHEMERAL_RSA</tt> means to always use ephemeral RSA keys
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when doing RSA operations. <tt class="constant">OP_NO_SSLv2</tt>, <tt class="constant">OP_NO_SSLv3</tt> and
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<tt class="constant">OP_NO_TLSv1</tt> means to disable those specific protocols. This is
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interesting if you're using e.g. <tt class="constant">SSLv23_METHOD</tt> to get an SSLv2-compatible
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handshake, but don't want to use SSLv2.
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<dl><dt><b><a name='l2h-133'><tt>SSLEAY_VERSION</tt></a></b>
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<dt><b><a name='l2h-156'><tt>SSLEAY_CFLAGS</tt></a></b><dd>
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<dt><b><a name='l2h-157'><tt>SSLEAY_BUILT_ON</tt></a></b><dd>
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<dt><b><a name='l2h-158'><tt>SSLEAY_PLATFORM</tt></a></b><dd>
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<dt><b><a name='l2h-159'><tt>SSLEAY_DIR</tt></a></b><dd>
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Constants used with <tt class="method">SSLeay_version</tt> to specify what OpenSSL version
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information to retrieve. See the man page for the <tt class="function">SSLeay_version</tt> C
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<dl><dt><b><a name='l2h-134'><tt>OPENSSL_VERSION_NUMBER</tt></a></b>
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An integer giving the version number of the OpenSSL library used to build this
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version of pyOpenSSL. See the man page for the <tt class="function">SSLeay_version</tt> C API
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<dl><dt><b><a name='l2h-135'><tt class='function'>SSLeay_version</tt></a></b>(<var>type</var>)
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Retrieve a string describing some aspect of the underlying OpenSSL version. The
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type passed in should be one of the <tt class="constant">SSLEAY_*</tt> constants defined in
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<dl><dt><b><a name='l2h-136'><tt>ContextType</tt></a></b>
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See <tt class="class">Context</tt>.
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<dl><dt><b>class <a name='l2h-137'><tt class='class'>Context</tt></a></b>(<var>method</var>)
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A class representing SSL contexts. Contexts define the parameters of one or
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more SSL connections.
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<var>method</var> should be <tt class="constant">SSLv2_METHOD</tt>, <tt class="constant">SSLv3_METHOD</tt>,
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<tt class="constant">SSLv23_METHOD</tt> or <tt class="constant">TLSv1_METHOD</tt>.
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<dl><dt><b><a name='l2h-138'><tt>ConnectionType</tt></a></b>
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See <tt class="class">Connection</tt>.
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<dl><dt><b>class <a name='l2h-139'><tt class='class'>Connection</tt></a></b>(<var>context, socket</var>)
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A class representing SSL connections.
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<var>context</var> should be an instance of <tt class="class">Context</tt> and <var>socket</var>
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should be a socket <A NAME="tex2html4"
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HREF="#foot1276"><SUP>3</SUP></A> object. <var>socket</var> may be
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<var>None</var>; in this case, the Connection is created with a memory BIO: see
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the <tt class="method">bio_read</tt>, <tt class="method">bio_write</tt>, and <tt class="method">bio_shutdown</tt>
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<dl><dt><b>exception <a name='l2h-140'><tt class='exception'>Error</tt></a></b>
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This exception is used as a base class for the other SSL-related
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exceptions, but may also be raised directly.
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Whenever this exception is raised directly, it has a list of error messages
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from the OpenSSL error queue, where each item is a tuple <code>(<var>lib</var>,
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<var>function</var>, <var>reason</var>)</code>. Here <var>lib</var>, <var>function</var> and <var>reason</var>
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are all strings, describing where and what the problem is. See <span class='manpage'><i>err</i>(3)</span>
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for more information.
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<dl><dt><b>exception <a name='l2h-141'><tt class='exception'>ZeroReturnError</tt></a></b>
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This exception matches the error return code <code>SSL_ERROR_ZERO_RETURN</code>, and
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is raised when the SSL Connection has been closed. In SSL 3.0 and TLS 1.0, this
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only occurs if a closure alert has occurred in the protocol, i.e. the
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connection has been closed cleanly. Note that this does not necessarily
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mean that the transport layer (e.g. a socket) has been closed.
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It may seem a little strange that this is an exception, but it does match an
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<code>SSL_ERROR</code> code, and is very convenient.
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<dl><dt><b>exception <a name='l2h-142'><tt class='exception'>WantReadError</tt></a></b>
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The operation did not complete; the same I/O method should be called again
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later, with the same arguments. Any I/O method can lead to this since new
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handshakes can occur at any time.
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The wanted read is for <i>dirty</i> data sent over the network, not the
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<i>clean</i> data inside the tunnel. For a socket based SSL connection,
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<i>read</i> means data coming at us over the network. Until that read
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succeeds, the attempted <tt class="method">OpenSSL.SSL.Connection.recv</tt>,
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<tt class="method">OpenSSL.SSL.Connection.send</tt>, or
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<tt class="method">OpenSSL.SSL.Connection.do_handshake</tt> is prevented or incomplete. You
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probably want to <tt class="method">select()</tt> on the socket before trying again.
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<dl><dt><b>exception <a name='l2h-143'><tt class='exception'>WantWriteError</tt></a></b>
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See <tt class="exception">WantReadError</tt>. The socket send buffer may be too full to
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<dl><dt><b>exception <a name='l2h-144'><tt class='exception'>WantX509LookupError</tt></a></b>
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The operation did not complete because an application callback has asked to be
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called again. The I/O method should be called again later, with the same
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arguments. Note: This won't occur in this version, as there are no such
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callbacks in this version.
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<dl><dt><b>exception <a name='l2h-145'><tt class='exception'>SysCallError</tt></a></b>
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The <tt class="exception">SysCallError</tt> occurs when there's an I/O error and OpenSSL's
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error queue does not contain any information. This can mean two things: An
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error in the transport protocol, or an end of file that violates the protocol.
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The parameter to the exception is always a pair <code>(<var>errnum</var>,
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<var>errstr</var>)</code>.
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<BR><HR><H4>Footnotes</H4>
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<DT><A NAME="foot1276">... socket</A><A
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href="openssl-ssl.html#tex2html4"><SUP>3</SUP></A></DT>
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<DD>Actually, all that is required is an object
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that <i>behaves</i> like a socket, you could even use files, even though
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it'd be tricky to get the handshakes right!
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<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></A>
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<LI><A NAME="tex2html289"
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href="openssl-context.html">3.3.1 Context objects </A>
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<LI><A NAME="tex2html290"
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href="openssl-connection.html">3.3.2 Connection objects </A>
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<span class="release-info">Release 0.13.</span>
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