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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <head> <title>3.3 SSL -- An interface to the SSL-specific parts of OpenSSL </title> <META NAME="description" CONTENT="3.3 SSL -- An interface to the SSL-specific parts of OpenSSL "> <META NAME="keywords" CONTENT="pyOpenSSL"> <META NAME="resource-type" CONTENT="document"> <META NAME="distribution" CONTENT="global"> <link rel="STYLESHEET" href="pyOpenSSL.css"> <LINK REL="previous" href="openssl-rand.html"> <LINK REL="up" href="openssl.html"> <LINK REL="next" href="openssl-context.html"> </head> <body> <DIV CLASS="navigation"> <table align="center" width="100%" cellpadding="0" cellspacing="2"> <tr> <td><A href="openssl-rand.html"><img src="previous.gif" border="0" height="32" alt="Previous Page" width="32"></A></td> <td><A href="openssl.html"><img src="up.gif" border="0" height="32" alt="Up One Level" width="32"></A></td> <td><A href="openssl-context.html"><img src="next.gif" border="0" height="32" alt="Next Page" width="32"></A></td> <td align="center" width="100%">Python OpenSSL Manual</td> <td><A href="contents.html"><img src="contents.gif" border="0" height="32" alt="Contents" width="32"></A></td> <td><img src="blank.gif" border="0" height="32" alt="" width="32"></td> <td><img src="blank.gif" border="0" height="32" alt="" width="32"></td> </tr></table> <b class="navlabel">Previous:</b> <a class="sectref" href="openssl-rand.html">3.2 rand </A> <b class="navlabel">Up:</b> <a class="sectref" href="openssl.html">3 OpenSSL </A> <b class="navlabel">Next:</b> <a class="sectref" href="openssl-context.html">3.3.1 Context objects</A> <br><hr> </DIV> <!--End of Navigation Panel--> <H2><A NAME="SECTION000430000000000000000"> </A> <BR> 3.3 <tt class="module">SSL</tt> -- An interface to the SSL-specific parts of OpenSSL </H2> <P> <P> This module handles things specific to SSL. There are two objects defined: Context, Connection. <P> <dl><dt><b><a name='l2h-109'><tt>SSLv2_METHOD</tt></a></b> <dd> <dt><b><a name='l2h-123'><tt>SSLv3_METHOD</tt></a></b><dd> <dt><b><a name='l2h-124'><tt>SSLv23_METHOD</tt></a></b><dd> <dt><b><a name='l2h-125'><tt>TLSv1_METHOD</tt></a></b><dd> These constants represent the different SSL methods to use when creating a context object. </dl> <P> <dl><dt><b><a name='l2h-110'><tt>VERIFY_NONE</tt></a></b> <dd> <dt><b><a name='l2h-126'><tt>VERIFY_PEER</tt></a></b><dd> <dt><b><a name='l2h-127'><tt>VERIFY_FAIL_IF_NO_PEER_CERT</tt></a></b><dd> These constants represent the verification mode used by the Context object's <tt class="method">set_verify</tt> method. </dl> <P> <dl><dt><b><a name='l2h-111'><tt>FILETYPE_PEM</tt></a></b> <dd> <dt><b><a name='l2h-128'><tt>FILETYPE_ASN1</tt></a></b><dd> File type constants used with the <tt class="method">use_certificate_file</tt> and <tt class="method">use_privatekey_file</tt> methods of Context objects. </dl> <P> <dl><dt><b><a name='l2h-112'><tt>OP_SINGLE_DH_USE</tt></a></b> <dd> <dt><b><a name='l2h-129'><tt>OP_EPHEMERAL_RSA</tt></a></b><dd> <dt><b><a name='l2h-130'><tt>OP_NO_SSLv2</tt></a></b><dd> <dt><b><a name='l2h-131'><tt>OP_NO_SSLv3</tt></a></b><dd> <dt><b><a name='l2h-132'><tt>OP_NO_TLSv1</tt></a></b><dd> Constants used with <tt class="method">set_options</tt> of Context objects. <tt class="constant">OP_SINGLE_DH_USE</tt> means to always create a new key when using ephemeral Diffie-Hellman. <tt class="constant">OP_EPHEMERAL_RSA</tt> means to always use ephemeral RSA keys when doing RSA operations. <tt class="constant">OP_NO_SSLv2</tt>, <tt class="constant">OP_NO_SSLv3</tt> and <tt class="constant">OP_NO_TLSv1</tt> means to disable those specific protocols. This is interesting if you're using e.g. <tt class="constant">SSLv23_METHOD</tt> to get an SSLv2-compatible handshake, but don't want to use SSLv2. </dl> <P> <dl><dt><b><a name='l2h-113'><tt>ContextType</tt></a></b> <dd> See <tt class="class">Context</tt>. </dl> <P> <dl><dt><b>class <a name='l2h-114'><tt class='class'>Context</tt></a></b>(<var>method</var>) <dd> A class representing SSL contexts. Contexts define the parameters of one or more SSL connections. <P> <var>method</var> should be <tt class="constant">SSLv2_METHOD</tt>, <tt class="constant">SSLv3_METHOD</tt>, <tt class="constant">SSLv23_METHOD</tt> or <tt class="constant">TLSv1_METHOD</tt>. </dl> <P> <dl><dt><b><a name='l2h-115'><tt>ConnectionType</tt></a></b> <dd> See <tt class="class">Connection</tt>. </dl> <P> <dl><dt><b>class <a name='l2h-116'><tt class='class'>Connection</tt></a></b>(<var>context, socket</var>) <dd> A class representing SSL connections. <P> <var>context</var> should be an instance of <tt class="class">Context</tt> and <var>socket</var> should be a socket <A NAME="tex2html4" HREF="#foot1112"><SUP>3</SUP></A> object. <var>socket</var> may be <var>None</var>; in this case, the Connection is created with a memory BIO: see the <tt class="method">bio_read</tt>, <tt class="method">bio_write</tt>, and <tt class="method">bio_shutdown</tt> methods. </dl> <P> <dl><dt><b>exception <a name='l2h-117'><tt class='exception'>Error</tt></a></b> <dd> This exception is used as a base class for the other SSL-related exceptions, but may also be raised directly. <P> Whenever this exception is raised directly, it has a list of error messages from the OpenSSL error queue, where each item is a tuple <code>(<var>lib</var>, <var>function</var>, <var>reason</var>)</code>. Here <var>lib</var>, <var>function</var> and <var>reason</var> are all strings, describing where and what the problem is. See <span class='manpage'><i>err</i>(3)</span> for more information. </dl> <P> <dl><dt><b>exception <a name='l2h-118'><tt class='exception'>ZeroReturnError</tt></a></b> <dd> This exception matches the error return code <code>SSL_ERROR_ZERO_RETURN</code>, 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. <P> It may seem a little strange that this is an exception, but it does match an <code>SSL_ERROR</code> code, and is very convenient. </dl> <P> <dl><dt><b>exception <a name='l2h-119'><tt class='exception'>WantReadError</tt></a></b> <dd> 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. <P> The wanted read is for <i>dirty</i> data sent over the network, not the <i>clean</i> data inside the tunnel. For a socket based SSL connection, <i>read</i> means data coming at us over the network. Until that read succeeds, the attempted <tt class="method">OpenSSL.SSL.Connection.recv</tt>, <tt class="method">OpenSSL.SSL.Connection.send</tt>, or <tt class="method">OpenSSL.SSL.Connection.do_handshake</tt> is prevented or incomplete. You probably want to <tt class="method">select()</tt> on the socket before trying again. </dl> <P> <dl><dt><b>exception <a name='l2h-120'><tt class='exception'>WantWriteError</tt></a></b> <dd> See <tt class="exception">WantReadError</tt>. The socket send buffer may be too full to write more data. </dl> <P> <dl><dt><b>exception <a name='l2h-121'><tt class='exception'>WantX509LookupError</tt></a></b> <dd> 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. </dl> <P> <dl><dt><b>exception <a name='l2h-122'><tt class='exception'>SysCallError</tt></a></b> <dd> The <tt class="exception">SysCallError</tt> 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 <code>(<var>errnum</var>, <var>errstr</var>)</code>. </dl> <P> <BR><HR><H4>Footnotes</H4> <DL> <DT><A NAME="foot1112">... socket</A><A href="openssl-ssl.html#tex2html4"><SUP>3</SUP></A></DT> <DD>Actually, all that is required is an object that <i>behaves</i> like a socket, you could even use files, even though it'd be tricky to get the handshakes right! </DD> </DL> <p><hr> <!--Table of Child-Links--> <A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></A> <UL CLASS="ChildLinks"> <LI><A NAME="tex2html261" href="openssl-context.html">3.3.1 Context objects </A> <LI><A NAME="tex2html262" href="openssl-connection.html">3.3.2 Connection objects </A> </UL> <!--End of Table of Child-Links--> <DIV CLASS="navigation"> <p><hr> <table align="center" width="100%" cellpadding="0" cellspacing="2"> <tr> <td><A href="openssl-rand.html"><img src="previous.gif" border="0" height="32" alt="Previous Page" width="32"></A></td> <td><A href="openssl.html"><img src="up.gif" border="0" height="32" alt="Up One Level" width="32"></A></td> <td><A href="openssl-context.html"><img src="next.gif" border="0" height="32" alt="Next Page" width="32"></A></td> <td align="center" width="100%">Python OpenSSL Manual</td> <td><A href="contents.html"><img src="contents.gif" border="0" height="32" alt="Contents" width="32"></A></td> <td><img src="blank.gif" border="0" height="32" alt="" width="32"></td> <td><img src="blank.gif" border="0" height="32" alt="" width="32"></td> </tr></table> <b class="navlabel">Previous:</b> <a class="sectref" href="openssl-rand.html">3.2 rand </A> <b class="navlabel">Up:</b> <a class="sectref" href="openssl.html">3 OpenSSL </A> <b class="navlabel">Next:</b> <a class="sectref" href="openssl-context.html">3.3.1 Context objects</A> <hr> <span class="release-info">Release 0.10.</span> </DIV> <!--End of Navigation Panel--> </BODY> </HTML>