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- Committer: Jean-Paul Calderone
- Date: 2011-09-11 19:49:43 UTC
- mfrom: (156.3.22 sphinx-doc)
- Revision ID: exarkun@divmod.com-20110911194943-ucaan2tzidk7ek5l
Convert the documentation from LaTeX/epytext to Sphinx/ReST
- files added:
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- doc/_templates
- doc/api
- files removed:
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- doc/html
- doc/tools
- doc/tools/html
- doc/tools/html/icons
- doc/tools/info
- doc/tools/paper-a4
- doc/tools/perl
- doc/tools/sgmlconv
- doc/tools/templates
- doc/tools/texinputs
- files renamed:
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doc/pyOpenSSL.tex
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\documentclass{howto}
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\title{Python OpenSSL Manual}
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\release{0.13}
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\author{Jean-Paul Calderone}
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\authoraddress{\email{exarkun@twistedmatrix.com}}
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\usepackage[english]{babel}
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\usepackage[T1]{fontenc}
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\begin{document}
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\maketitle
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\begin{abstract}
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\noindent
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This module is a rather thin wrapper around (a subset of) the OpenSSL library.
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With thin wrapper I mean that a lot of the object methods do nothing more than
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calling a corresponding function in the OpenSSL library.
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\end{abstract}
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\tableofcontents
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\section{Introduction \label{intro}}
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The reason pyOpenSSL was created is that the SSL support in the socket module
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in Python 2.1 (the contemporary version of Python when the pyOpenSSL project
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was begun) was severely limited. Other OpenSSL wrappers for Python at the time
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were also limited, though in different ways. Unfortunately, Python's standard
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library SSL support has remained weak, although other packages (such as
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M2Crypto\footnote{See \url{http://chandlerproject.org/Projects/MeTooCrypto}})
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have made great advances and now equal or exceed pyOpenSSL's functionality.
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The reason pyOpenSSL continues to be maintained is that there is a significant
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user community around it, as well as a large amount of software which depends
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on it. It is a great benefit to many people for pyOpenSSL to continue to exist
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and advance.
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\section{Building and Installing \label{building}}
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These instructions can also be found in the file \verb|INSTALL|.
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I have tested this on Debian Linux systems (woody and sid), Solaris 2.6 and
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2.7. Others have successfully compiled it on Windows and NT.
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\subsection{Building the Module on a Unix System \label{building-unix}}
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pyOpenSSL uses distutils, so there really shouldn't be any problems. To build
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the library:
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\begin{verbatim}
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python setup.py build
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\end{verbatim}
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If your OpenSSL header files aren't in \verb|/usr/include|, you may need to
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supply the \verb|-I| flag to let the setup script know where to look. The same
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goes for the libraries of course, use the \verb|-L| flag. Note that
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\verb|build| won't accept these flags, so you have to run first
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\verb|build_ext| and then \verb|build|! Example:
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\begin{verbatim}
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python setup.py build_ext -I/usr/local/ssl/include -L/usr/local/ssl/lib
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python setup.py build
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\end{verbatim}
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Now you should have a directory called \verb|OpenSSL| that contains e.g.
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\verb|SSL.so| and \verb|__init__.py| somewhere in the build dicrectory,
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so just:
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\begin{verbatim}
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python setup.py install
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\end{verbatim}
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If you, for some arcane reason, don't want the module to appear in the
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\verb|site-packages| directory, use the \verb|--prefix| option.
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You can, of course, do
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\begin{verbatim}
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python setup.py --help
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\end{verbatim}
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to find out more about how to use the script.
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\subsection{Building the Module on a Windows System \label{building-windows}}
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Big thanks to Itamar Shtull-Trauring and Oleg Orlov for their help with
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Windows build instructions. Same as for Unix systems, we have to separate
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the \verb|build_ext| and the \verb|build|.
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Building the library:
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\begin{verbatim}
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setup.py build_ext -I ...\openssl\inc32 -L ...\openssl\out32dll
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setup.py build
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\end{verbatim}
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Where \verb|...\openssl| is of course the location of your OpenSSL installation.
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Installation is the same as for Unix systems:
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\begin{verbatim}
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setup.py install
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\end{verbatim}
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And similarily, you can do
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\begin{verbatim}
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setup.py --help
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\end{verbatim}
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to get more information.
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\section{\module{OpenSSL} --- Python interface to OpenSSL \label{openssl}}
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\declaremodule{extension}{OpenSSL}
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\modulesynopsis{Python interface to OpenSSL}
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This package provides a high-level interface to the functions in the
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OpenSSL library. The following modules are defined:
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\begin{datadesc}{crypto}
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Generic cryptographic module. Note that if anything is incomplete, this module is!
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\end{datadesc}
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\begin{datadesc}{rand}
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An interface to the OpenSSL pseudo random number generator.
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\end{datadesc}
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\begin{datadesc}{SSL}
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An interface to the SSL-specific parts of OpenSSL.
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\end{datadesc}
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% % % crypto moduleOpenSSL
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\subsection{\module{crypto} --- Generic cryptographic module \label{openssl-crypto}}
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\declaremodule{extension}{crypto}
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\modulesynopsis{Generic cryptographic module}
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\begin{datadesc}{X509Type}
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See \class{X509}.
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\end{datadesc}
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\begin{classdesc}{X509}{}
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A class representing X.509 certificates.
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\end{classdesc}
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\begin{datadesc}{X509NameType}
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See \class{X509Name}.
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\end{datadesc}
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\begin{classdesc}{X509Name}{x509name}
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A class representing X.509 Distinguished Names.
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This constructor creates a copy of \var{x509name} which should be an
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instance of \class{X509Name}.
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\end{classdesc}
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\begin{datadesc}{X509ReqType}
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See \class{X509Req}.
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\end{datadesc}
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\begin{classdesc}{X509Req}{}
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A class representing X.509 certificate requests.
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\end{classdesc}
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\begin{datadesc}{X509StoreType}
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A Python type object representing the X509Store object type.
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\end{datadesc}
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\begin{datadesc}{PKeyType}
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See \class{PKey}.
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\end{datadesc}
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\begin{classdesc}{PKey}{}
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A class representing DSA or RSA keys.
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\end{classdesc}
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\begin{datadesc}{PKCS7Type}
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A Python type object representing the PKCS7 object type.
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\end{datadesc}
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\begin{datadesc}{PKCS12Type}
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A Python type object representing the PKCS12 object type.
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\end{datadesc}
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\begin{datadesc}{X509ExtensionType}
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See \class{X509Extension}.
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\end{datadesc}
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\begin{classdesc}{X509Extension}{typename, critical, value\optional{, subject}\optional{, issuer}}
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A class representing an X.509 v3 certificate extensions.
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See \url{http://openssl.org/docs/apps/x509v3_config.html\#STANDARD_EXTENSIONS}
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for \var{typename} strings and their options.
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Optional parameters \var{subject} and \var{issuer} must be X509 objects.
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\end{classdesc}
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\begin{datadesc}{NetscapeSPKIType}
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See \class{NetscapeSPKI}.
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\end{datadesc}
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\begin{classdesc}{NetscapeSPKI}{\optional{enc}}
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A class representing Netscape SPKI objects.
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If the \var{enc} argument is present, it should be a base64-encoded string
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representing a NetscapeSPKI object, as returned by the \method{b64_encode}
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method.
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\end{classdesc}
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\begin{classdesc}{CRL}{}
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A class representing Certifcate Revocation List objects.
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\end{classdesc}
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\begin{classdesc}{Revoked}{}
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A class representing Revocation objects of CRL.
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\end{classdesc}
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\begin{datadesc}{FILETYPE_PEM}
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\dataline{FILETYPE_ASN1}
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File type constants.
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\end{datadesc}
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\begin{datadesc}{TYPE_RSA}
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\dataline{TYPE_DSA}
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Key type constants.
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\end{datadesc}
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\begin{excdesc}{Error}
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Generic exception used in the \module{crypto} module.
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\end{excdesc}
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\begin{funcdesc}{dump_certificate}{type, cert}
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Dump the certificate \var{cert} into a buffer string encoded with the type
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\var{type}.
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\end{funcdesc}
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\begin{funcdesc}{dump_certificate_request}{type, req}
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Dump the certificate request \var{req} into a buffer string encoded with the
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type \var{type}.
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\end{funcdesc}
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\begin{funcdesc}{dump_privatekey}{type, pkey\optional{, cipher, passphrase}}
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Dump the private key \var{pkey} into a buffer string encoded with the type
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\var{type}, optionally (if \var{type} is \constant{FILETYPE_PEM}) encrypting it
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using \var{cipher} and \var{passphrase}.
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\var{passphrase} must be either a string or a callback for providing the
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pass phrase.
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\end{funcdesc}
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\begin{funcdesc}{load_certificate}{type, buffer}
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Load a certificate (X509) from the string \var{buffer} encoded with the
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type \var{type}.
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\end{funcdesc}
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\begin{funcdesc}{load_certificate_request}{type, buffer}
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Load a certificate request (X509Req) from the string \var{buffer} encoded with
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the type \var{type}.
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\end{funcdesc}
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\begin{funcdesc}{load_privatekey}{type, buffer\optional{, passphrase}}
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Load a private key (PKey) from the string \var{buffer} encoded with
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the type \var{type} (must be one of \constant{FILETYPE_PEM} and
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\constant{FILETYPE_ASN1}).
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\var{passphrase} must be either a string or a callback for providing the
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pass phrase.
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\end{funcdesc}
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\begin{funcdesc}{load_crl}{type, buffer}
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Load Certificate Revocation List (CRL) data from a string \var{buffer}.
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\var{buffer} encoded with the type \var{type}. The type \var{type}
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must either \constant{FILETYPE_PEM} or \constant{FILETYPE_ASN1}).
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\end{funcdesc}
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\begin{funcdesc}{load_pkcs7_data}{type, buffer}
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Load pkcs7 data from the string \var{buffer} encoded with the type \var{type}.
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\end{funcdesc}
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\begin{funcdesc}{load_pkcs12}{buffer\optional{, passphrase}}
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Load pkcs12 data from the string \var{buffer}. If the pkcs12 structure is
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encrypted, a \var{passphrase} must be included. The MAC is always
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checked and thus required.
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See also the man page for the C function \function{PKCS12_parse}.
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\end{funcdesc}
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\begin{funcdesc}{sign}{key, data, digest}
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Sign a data string using the given key and message digest.
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\var{key} is a \code{PKey} instance. \var{data} is a \code{str} instance.
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\var{digest} is a \code{str} naming a supported message digest type, for example
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\code{``sha1''}.
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\versionadded{0.11}
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\end{funcdesc}
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\begin{funcdesc}{verify}{certificate, signature, data, digest}
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Verify the signature for a data string.
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\var{certificate} is a \code{X509} instance corresponding to the private key
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which generated the signature. \var{signature} is a \var{str} instance giving
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the signature itself. \var{data} is a \var{str} instance giving the data to
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which the signature applies. \var{digest} is a \var{str} instance naming the
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message digest type of the signature, for example \code{``sha1''}.
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\versionadded{0.11}
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\end{funcdesc}
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\subsubsection{X509 objects \label{openssl-x509}}
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X509 objects have the following methods:
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\begin{methoddesc}[X509]{get_issuer}{}
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Return an X509Name object representing the issuer of the certificate.
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\end{methoddesc}
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\begin{methoddesc}[X509]{get_pubkey}{}
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Return a PKey object representing the public key of the certificate.
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\end{methoddesc}
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\begin{methoddesc}[X509]{get_serial_number}{}
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Return the certificate serial number.
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\end{methoddesc}
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\begin{methoddesc}[X509]{get_signature_algorithm}{}
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Return the signature algorithm used in the certificate. If the algorithm is
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undefined, raise \code{ValueError}.
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\end{methoddesc}
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\begin{methoddesc}[X509]{get_subject}{}
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Return an X509Name object representing the subject of the certificate.
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\end{methoddesc}
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\begin{methoddesc}[X509]{get_version}{}
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Return the certificate version.
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\end{methoddesc}
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\begin{methoddesc}[X509]{get_notBefore}{}
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Return a string giving the time before which the certificate is not valid. The
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string is formatted as an ASN1 GENERALIZEDTIME:
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\begin{verbatim}
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YYYYMMDDhhmmssZ
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YYYYMMDDhhmmss+hhmm
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YYYYMMDDhhmmss-hhmm
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\end{verbatim}
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If no value exists for this field, \code{None} is returned.
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\end{methoddesc}
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\begin{methoddesc}[X509]{get_notAfter}{}
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Return a string giving the time after which the certificate is not valid. The
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string is formatted as an ASN1 GENERALIZEDTIME:
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\begin{verbatim}
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YYYYMMDDhhmmssZ
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YYYYMMDDhhmmss+hhmm
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YYYYMMDDhhmmss-hhmm
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\end{verbatim}
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If no value exists for this field, \code{None} is returned.
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\end{methoddesc}
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\begin{methoddesc}[X509]{set_notBefore}{when}
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Change the time before which the certificate is not valid. \var{when} is a
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string formatted as an ASN1 GENERALIZEDTIME:
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\begin{verbatim}
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YYYYMMDDhhmmssZ
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YYYYMMDDhhmmss+hhmm
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YYYYMMDDhhmmss-hhmm
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\end{verbatim}
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\end{methoddesc}
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\begin{methoddesc}[X509]{set_notAfter}{when}
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Change the time after which the certificate is not valid. \var{when} is a
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string formatted as an ASN1 GENERALIZEDTIME:
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\begin{verbatim}
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YYYYMMDDhhmmssZ
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YYYYMMDDhhmmss+hhmm
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YYYYMMDDhhmmss-hhmm
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\end{verbatim}
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\end{methoddesc}
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\begin{methoddesc}[X509]{gmtime_adj_notBefore}{time}
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Adjust the timestamp (in GMT) when the certificate starts being valid.
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\end{methoddesc}
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\begin{methoddesc}[X509]{gmtime_adj_notAfter}{time}
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Adjust the timestamp (in GMT) when the certificate stops being valid.
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\end{methoddesc}
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\begin{methoddesc}[X509]{has_expired}{}
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Checks the certificate's time stamp against current time. Returns true if the
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certificate has expired and false otherwise.
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\end{methoddesc}
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\begin{methoddesc}[X509]{set_issuer}{issuer}
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Set the issuer of the certificate to \var{issuer}.
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\end{methoddesc}
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\begin{methoddesc}[X509]{set_pubkey}{pkey}
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Set the public key of the certificate to \var{pkey}.
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\end{methoddesc}
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\begin{methoddesc}[X509]{set_serial_number}{serialno}
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Set the serial number of the certificate to \var{serialno}.
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\end{methoddesc}
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\begin{methoddesc}[X509]{set_subject}{subject}
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Set the subject of the certificate to \var{subject}.
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\end{methoddesc}
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\begin{methoddesc}[X509]{set_version}{version}
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Set the certificate version to \var{version}.
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\end{methoddesc}
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\begin{methoddesc}[X509]{sign}{pkey, digest}
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Sign the certificate, using the key \var{pkey} and the message digest algorithm
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identified by the string \var{digest}.
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\end{methoddesc}
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\begin{methoddesc}[X509]{subject_name_hash}{}
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Return the hash of the certificate subject.
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\end{methoddesc}
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\begin{methoddesc}[X509]{digest}{digest_name}
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Return a digest of the certificate, using the \var{digest_name} method.
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\var{digest_name} must be a string describing a digest algorithm supported
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by OpenSSL (by EVP_get_digestbyname, specifically). For example,
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\constant{"md5"} or \constant{"sha1"}.
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\end{methoddesc}
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\begin{methoddesc}[X509]{add_extensions}{extensions}
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Add the extensions in the sequence \var{extensions} to the certificate.
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\end{methoddesc}
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\begin{methoddesc}[X509]{get_extension_count}{}
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Return the number of extensions on this certificate.
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\versionadded{0.12}
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\end{methoddesc}
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\begin{methoddesc}[X509]{get_extension}{index}
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Retrieve the extension on this certificate at the given index.
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Extensions on a certificate are kept in order. The index parameter selects
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which extension will be returned. The returned object will be an X509Extension
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instance.
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\versionadded{0.12}
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\end{methoddesc}
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\subsubsection{X509Name objects \label{openssl-x509name}}
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X509Name objects have the following methods:
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\begin{methoddesc}[X509Name]{hash}{}
451
Return an integer giving the first four bytes of the MD5 digest of the DER
452
representation of the name.
453
\end{methoddesc}
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\begin{methoddesc}[X509Name]{der}{}
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Return a string giving the DER representation of the name.
457
\end{methoddesc}
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\begin{methoddesc}[X509Name]{get_components}{}
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Return a list of two-tuples of strings giving the components of the name.
461
\end{methoddesc}
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463
X509Name objects have the following members:
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\begin{memberdesc}[X509Name]{countryName}
466
The country of the entity. \code{C} may be used as an alias for
467
\code{countryName}.
468
\end{memberdesc}
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\begin{memberdesc}[X509Name]{stateOrProvinceName}
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The state or province of the entity. \code{ST} may be used as an alias for
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\code{stateOrProvinceName}�
473
\end{memberdesc}
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\begin{memberdesc}[X509Name]{localityName}
476
The locality of the entity. \code{L} may be used as an alias for
477
\code{localityName}.
478
\end{memberdesc}
479
480
\begin{memberdesc}[X509Name]{organizationName}
481
The organization name of the entity. \code{O} may be used as an alias for
482
\code{organizationName}.
483
\end{memberdesc}
484
485
\begin{memberdesc}[X509Name]{organizationalUnitName}
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The organizational unit of the entity. \code{OU} may be used as an alias for
487
\code{organizationalUnitName}.
488
\end{memberdesc}
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490
\begin{memberdesc}[X509Name]{commonName}
491
The common name of the entity. \code{CN} may be used as an alias for
492
\code{commonName}.
493
\end{memberdesc}
494
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\begin{memberdesc}[X509Name]{emailAddress}
496
The e-mail address of the entity.
497
\end{memberdesc}
498
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\subsubsection{X509Req objects \label{openssl-x509req}}
500
501
X509Req objects have the following methods:
502
503
\begin{methoddesc}[X509Req]{get_pubkey}{}
504
Return a PKey object representing the public key of the certificate request.
505
\end{methoddesc}
506
507
\begin{methoddesc}[X509Req]{get_subject}{}
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Return an X509Name object representing the subject of the certificate.
509
\end{methoddesc}
510
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\begin{methoddesc}[X509Req]{set_pubkey}{pkey}
512
Set the public key of the certificate request to \var{pkey}.
513
\end{methoddesc}
514
515
\begin{methoddesc}[X509Req]{sign}{pkey, digest}
516
Sign the certificate request, using the key \var{pkey} and the message digest
517
algorithm identified by the string \var{digest}.
518
\end{methoddesc}
519
520
\begin{methoddesc}[X509Req]{verify}{pkey}
521
Verify a certificate request using the public key \var{pkey}.
522
\end{methoddesc}
523
524
\begin{methoddesc}[X509Req]{set_version}{version}
525
Set the version (RFC 2459, 4.1.2.1) of the certificate request to
526
\var{version}.
527
\end{methoddesc}
528
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\begin{methoddesc}[X509Req]{get_version}{}
530
Get the version (RFC 2459, 4.1.2.1) of the certificate request.
531
\end{methoddesc}
532
533
\subsubsection{X509Store objects \label{openssl-x509store}}
534
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The X509Store object has currently just one method:
536
537
\begin{methoddesc}[X509Store]{add_cert}{cert}
538
Add the certificate \var{cert} to the certificate store.
539
\end{methoddesc}
540
541
\subsubsection{PKey objects \label{openssl-pkey}}
542
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The PKey object has the following methods:
544
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\begin{methoddesc}[PKey]{bits}{}
546
Return the number of bits of the key.
547
\end{methoddesc}
548
549
\begin{methoddesc}[PKey]{generate_key}{type, bits}
550
Generate a public/private key pair of the type \var{type} (one of
551
\constant{TYPE_RSA} and \constant{TYPE_DSA}) with the size \var{bits}.
552
\end{methoddesc}
553
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\begin{methoddesc}[PKey]{type}{}
555
Return the type of the key.
556
\end{methoddesc}
557
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\begin{methoddesc}[PKey]{check}{}
559
Check the consistency of this key, returning True if it is consistent and
560
raising an exception otherwise. This is only valid for RSA keys. See the
561
OpenSSL RSA_check_key man page for further limitations.
562
\end{methoddesc}
563
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\subsubsection{PKCS7 objects \label{openssl-pkcs7}}
565
566
PKCS7 objects have the following methods:
567
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\begin{methoddesc}[PKCS7]{type_is_signed}{}
569
FIXME
570
\end{methoddesc}
571
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\begin{methoddesc}[PKCS7]{type_is_enveloped}{}
573
FIXME
574
\end{methoddesc}
575
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\begin{methoddesc}[PKCS7]{type_is_signedAndEnveloped}{}
577
FIXME
578
\end{methoddesc}
579
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\begin{methoddesc}[PKCS7]{type_is_data}{}
581
FIXME
582
\end{methoddesc}
583
584
\begin{methoddesc}[PKCS7]{get_type_name}{}
585
Get the type name of the PKCS7.
586
\end{methoddesc}
587
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\subsubsection{PKCS12 objects \label{openssl-pkcs12}}
589
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PKCS12 objects have the following methods:
591
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\begin{methoddesc}[PKCS12]{export}{\optional{passphrase=None}\optional{, iter=2048}\optional{, maciter=1}}
593
Returns a PKCS12 object as a string.
594
595
The optional \var{passphrase} must be a string not a callback.
596
597
See also the man page for the C function \function{PKCS12_create}.
598
\end{methoddesc}
599
600
\begin{methoddesc}[PKCS12]{get_ca_certificates}{}
601
Return CA certificates within the PKCS12 object as a tuple. Returns
602
\constant{None} if no CA certificates are present.
603
\end{methoddesc}
604
605
\begin{methoddesc}[PKCS12]{get_certificate}{}
606
Return certificate portion of the PKCS12 structure.
607
\end{methoddesc}
608
609
\begin{methoddesc}[PKCS12]{get_friendlyname}{}
610
Return friendlyName portion of the PKCS12 structure.
611
\end{methoddesc}
612
613
\begin{methoddesc}[PKCS12]{get_privatekey}{}
614
Return private key portion of the PKCS12 structure
615
\end{methoddesc}
616
617
\begin{methoddesc}[PKCS12]{set_ca_certificates}{cacerts}
618
Replace or set the CA certificates within the PKCS12 object with the sequence \var{cacerts}.
619
620
Set \var{cacerts} to \constant{None} to remove all CA certificates.
621
\end{methoddesc}
622
623
\begin{methoddesc}[PKCS12]{set_certificate}{cert}
624
Replace or set the certificate portion of the PKCS12 structure.
625
\end{methoddesc}
626
627
\begin{methoddesc}[PKCS12]{set_friendlyname}{name}
628
Replace or set the friendlyName portion of the PKCS12 structure.
629
\end{methoddesc}
630
631
\begin{methoddesc}[PKCS12]{set_privatekey}{pkey}
632
Replace or set private key portion of the PKCS12 structure
633
\end{methoddesc}
634
635
\subsubsection{X509Extension objects \label{openssl-509ext}}
636
637
X509Extension objects have several methods:
638
639
\begin{methoddesc}[X509Extension]{get_critical}{}
640
Return the critical field of the extension object.
641
\end{methoddesc}
642
643
\begin{methoddesc}[X509Extension]{get_short_name}{}
644
Retrieve the short descriptive name for this extension.
645
646
The result is a byte string like \code{``basicConstraints''}.
647
\versionadded{0.12}
648
\end{methoddesc}
649
650
\begin{methoddesc}[X509Extension]{get_data}{}
651
Retrieve the data for this extension.
652
653
The result is the ASN.1 encoded form of the extension data as a byte string.
654
\versionadded{0.12}
655
\end{methoddesc}
656
657
\subsubsection{NetscapeSPKI objects \label{openssl-netscape-spki}}
658
659
NetscapeSPKI objects have the following methods:
660
661
\begin{methoddesc}[NetscapeSPKI]{b64_encode}{}
662
Return a base64-encoded string representation of the object.
663
\end{methoddesc}
664
665
\begin{methoddesc}[NetscapeSPKI]{get_pubkey}{}
666
Return the public key of object.
667
\end{methoddesc}
668
669
\begin{methoddesc}[NetscapeSPKI]{set_pubkey}{key}
670
Set the public key of the object to \var{key}.
671
\end{methoddesc}
672
673
\begin{methoddesc}[NetscapeSPKI]{sign}{key, digest_name}
674
Sign the NetscapeSPKI object using the given \var{key} and
675
\var{digest_name}. \var{digest_name} must be a string describing a digest
676
algorithm supported by OpenSSL (by EVP_get_digestbyname, specifically). For
677
example, \constant{"md5"} or \constant{"sha1"}.
678
\end{methoddesc}
679
680
\begin{methoddesc}[NetscapeSPKI]{verify}{key}
681
Verify the NetscapeSPKI object using the given \var{key}.
682
\end{methoddesc}
683
684
\subsubsection{CRL objects \label{crl}}
685
686
CRL objects have the following methods:
687
688
\begin{methoddesc}[CRL]{add_revoked}{revoked}
689
Add a Revoked object to the CRL, by value not reference.
690
\end{methoddesc}
691
692
\begin{methoddesc}[CRL]{export}{cert, key\optional{, type=FILETYPE_PEM}\optional{, days=100}}
693
Use \var{cert} and \var{key} to sign the CRL and return the CRL as a string.
694
\var{days} is the number of days before the next CRL is due.
695
\end{methoddesc}
696
697
\begin{methoddesc}[CRL]{get_revoked}{}
698
Return a tuple of Revoked objects, by value not reference.
699
\end{methoddesc}
700
701
\subsubsection{Revoked objects \label{revoked}}
702
703
Revoked objects have the following methods:
704
705
\begin{methoddesc}[Revoked]{all_reasons}{}
706
Return a list of all supported reasons.
707
\end{methoddesc}
708
709
\begin{methoddesc}[Revoked]{get_reason}{}
710
Return the revocation reason as a str. Can be
711
None, which differs from "Unspecified".
712
\end{methoddesc}
713
714
\begin{methoddesc}[Revoked]{get_rev_date}{}
715
Return the revocation date as a str.
716
The string is formatted as an ASN1 GENERALIZEDTIME.
717
\end{methoddesc}
718
719
\begin{methoddesc}[Revoked]{get_serial}{}
720
Return a str containing a hex number of the serial of the revoked certificate.
721
\end{methoddesc}
722
723
\begin{methoddesc}[Revoked]{set_reason}{reason}
724
Set the revocation reason. \var{reason} must
725
be None or a string, but the values are limited.
726
Spaces and case are ignored. See \method{all_reasons}.
727
\end{methoddesc}
728
729
\begin{methoddesc}[Revoked]{set_rev_date}{date}
730
Set the revocation date.
731
The string is formatted as an ASN1 GENERALIZEDTIME.
732
\end{methoddesc}
733
734
\begin{methoddesc}[Revoked]{set_serial}{serial}
735
\var{serial} is a string containing a hex number of the serial of the revoked certificate.
736
\end{methoddesc}
737
738
739
% % % rand module
740
741
\subsection{\module{rand} --- An interface to the OpenSSL pseudo random number generator \label{openssl-rand}}
742
743
\declaremodule{extension}{rand}
744
\modulesynopsis{An interface to the OpenSSL pseudo random number generator}
745
746
This module handles the OpenSSL pseudo random number generator (PRNG) and
747
declares the following:
748
749
\begin{funcdesc}{add}{string, entropy}
750
Mix bytes from \var{string} into the PRNG state. The \var{entropy} argument is
751
(the lower bound of) an estimate of how much randomness is contained in
752
\var{string}, measured in bytes. For more information, see e.g. \rfc{1750}.
753
\end{funcdesc}
754
755
\begin{funcdesc}{bytes}{num_bytes}
756
Get some random bytes from the PRNG as a string.
757
758
This is a wrapper for the C function \function{RAND_bytes}.
759
\end{funcdesc}
760
761
\begin{funcdesc}{cleanup}{}
762
Erase the memory used by the PRNG.
763
764
This is a wrapper for the C function \function{RAND_cleanup}.
765
\end{funcdesc}
766
767
\begin{funcdesc}{egd}{path\optional{, bytes}}
768
Query the Entropy Gathering Daemon\footnote{See
769
\url{http://www.lothar.com/tech/crypto/}} on socket \var{path} for \var{bytes}
770
bytes of random data and and uses \function{add} to seed the PRNG. The default
771
value of \var{bytes} is 255.
772
\end{funcdesc}
773
774
\begin{funcdesc}{load_file}{path\optional{, bytes}}
775
Read \var{bytes} bytes (or all of it, if \var{bytes} is negative) of data from
776
the file \var{path} to seed the PRNG. The default value of \var{bytes} is -1.
777
\end{funcdesc}
778
779
\begin{funcdesc}{screen}{}
780
Add the current contents of the screen to the PRNG state.
781
Availability: Windows.
782
\end{funcdesc}
783
784
\begin{funcdesc}{seed}{string}
785
This is equivalent to calling \function{add} with \var{entropy} as the length
786
of the string.
787
\end{funcdesc}
788
789
\begin{funcdesc}{status}{}
790
Returns true if the PRNG has been seeded with enough data, and false otherwise.
791
\end{funcdesc}
792
793
\begin{funcdesc}{write_file}{path}
794
Write a number of random bytes (currently 1024) to the file \var{path}. This
795
file can then be used with \function{load_file} to seed the PRNG again.
796
\end{funcdesc}
797
798
\begin{excdesc}{Error}
799
If the current RAND method supports any errors, this is raised when needed.
800
The default method does not raise this when the entropy pool is depleted.
801
802
Whenever this exception is raised directly, it has a list of error messages
803
from the OpenSSL error queue, where each item is a tuple \code{(\var{lib},
804
\var{function}, \var{reason})}. Here \var{lib}, \var{function} and \var{reason}
805
are all strings, describing where and what the problem is. See \manpage{err}{3}
806
for more information.
807
\end{excdesc}
808
809
810
% % % SSL module
811
812
\subsection{\module{SSL} --- An interface to the SSL-specific parts of OpenSSL \label{openssl-ssl}}
813
814
\declaremodule{extension}{SSL}
815
\modulesynopsis{An interface to the SSL-specific parts of OpenSSL}
816
817
This module handles things specific to SSL. There are two objects defined:
818
Context, Connection.
819
820
\begin{datadesc}{SSLv2_METHOD}
821
\dataline{SSLv3_METHOD}
822
\dataline{SSLv23_METHOD}
823
\dataline{TLSv1_METHOD}
824
These constants represent the different SSL methods to use when creating a
825
context object.
826
\end{datadesc}
827
828
\begin{datadesc}{VERIFY_NONE}
829
\dataline{VERIFY_PEER}
830
\dataline{VERIFY_FAIL_IF_NO_PEER_CERT}
831
These constants represent the verification mode used by the Context
832
object's \method{set_verify} method.
833
\end{datadesc}
834
835
\begin{datadesc}{FILETYPE_PEM}
836
\dataline{FILETYPE_ASN1}
837
File type constants used with the \method{use_certificate_file} and
838
\method{use_privatekey_file} methods of Context objects.
839
\end{datadesc}
840
841
\begin{datadesc}{OP_SINGLE_DH_USE}
842
\dataline{OP_EPHEMERAL_RSA}
843
\dataline{OP_NO_SSLv2}
844
\dataline{OP_NO_SSLv3}
845
\dataline{OP_NO_TLSv1}
846
\dataline{OP_NO_TICKET}
847
\dataline{OP_NO_COMPRESSION}
848
Constants used with \method{set_options} of Context objects.
849
\constant{OP_SINGLE_DH_USE} means to always create a new key when using ephemeral
850
Diffie-Hellman. \constant{OP_EPHEMERAL_RSA} means to always use ephemeral RSA keys
851
when doing RSA operations. \constant{OP_NO_SSLv2}, \constant{OP_NO_SSLv3} and
852
\constant{OP_NO_TLSv1} means to disable those specific protocols. This is
853
interesting if you're using e.g. \constant{SSLv23_METHOD} to get an SSLv2-compatible
854
handshake, but don't want to use SSLv2.
855
\end{datadesc}
856
857
\begin{datadesc}{MODE_NO_COMPRESSION}
858
Constant used with \method{set_mode} of Context objects to disable automatic
859
compression of application traffic.
860
\end{datadesc}
861
862
\begin{datadesc}{SSLEAY_VERSION}
863
\dataline{SSLEAY_CFLAGS}
864
\dataline{SSLEAY_BUILT_ON}
865
\dataline{SSLEAY_PLATFORM}
866
\dataline{SSLEAY_DIR}
867
Constants used with \method{SSLeay_version} to specify what OpenSSL version
868
information to retrieve. See the man page for the \function{SSLeay_version} C
869
API for details.
870
\end{datadesc}
871
872
\begin{datadesc}{OPENSSL_VERSION_NUMBER}
873
An integer giving the version number of the OpenSSL library used to build this
874
version of pyOpenSSL. See the man page for the \function{SSLeay_version} C API
875
for details.
876
\end{datadesc}
877
878
\begin{funcdesc}{SSLeay_version}{type}
879
Retrieve a string describing some aspect of the underlying OpenSSL version. The
880
type passed in should be one of the \constant{SSLEAY_*} constants defined in
881
this module.
882
\end{funcdesc}
883
884
\begin{datadesc}{ContextType}
885
See \class{Context}.
886
\end{datadesc}
887
888
\begin{classdesc}{Context}{method}
889
A class representing SSL contexts. Contexts define the parameters of one or
890
more SSL connections.
891
892
\var{method} should be \constant{SSLv2_METHOD}, \constant{SSLv3_METHOD},
893
\constant{SSLv23_METHOD} or \constant{TLSv1_METHOD}.
894
\end{classdesc}
895
896
\begin{datadesc}{ConnectionType}
897
See \class{Connection}.
898
\end{datadesc}
899
900
\begin{classdesc}{Connection}{context, socket}
901
A class representing SSL connections.
902
903
\var{context} should be an instance of \class{Context} and \var{socket}
904
should be a socket \footnote{Actually, all that is required is an object
905
that \emph{behaves} like a socket, you could even use files, even though
906
it'd be tricky to get the handshakes right!} object. \var{socket} may be
907
\var{None}; in this case, the Connection is created with a memory BIO: see
908
the \method{bio_read}, \method{bio_write}, and \method{bio_shutdown}
909
methods.
910
\end{classdesc}
911
912
\begin{excdesc}{Error}
913
This exception is used as a base class for the other SSL-related
914
exceptions, but may also be raised directly.
915
916
Whenever this exception is raised directly, it has a list of error messages
917
from the OpenSSL error queue, where each item is a tuple \code{(\var{lib},
918
\var{function}, \var{reason})}. Here \var{lib}, \var{function} and \var{reason}
919
are all strings, describing where and what the problem is. See \manpage{err}{3}
920
for more information.
921
\end{excdesc}
922
923
\begin{excdesc}{ZeroReturnError}
924
This exception matches the error return code \code{SSL_ERROR_ZERO_RETURN}, and
925
is raised when the SSL Connection has been closed. In SSL 3.0 and TLS 1.0, this
926
only occurs if a closure alert has occurred in the protocol, i.e. the
927
connection has been closed cleanly. Note that this does not necessarily
928
mean that the transport layer (e.g. a socket) has been closed.
929
930
It may seem a little strange that this is an exception, but it does match an
931
\code{SSL_ERROR} code, and is very convenient.
932
\end{excdesc}
933
934
\begin{excdesc}{WantReadError}
935
The operation did not complete; the same I/O method should be called again
936
later, with the same arguments. Any I/O method can lead to this since new
937
handshakes can occur at any time.
938
939
The wanted read is for \emph{dirty} data sent over the network, not the
940
\emph{clean} data inside the tunnel. For a socket based SSL connection,
941
\emph{read} means data coming at us over the network. Until that read
942
succeeds, the attempted \method{OpenSSL.SSL.Connection.recv},
943
\method{OpenSSL.SSL.Connection.send}, or
944
\method{OpenSSL.SSL.Connection.do_handshake} is prevented or incomplete. You
945
probably want to \method{select()} on the socket before trying again.
946
\end{excdesc}
947
948
\begin{excdesc}{WantWriteError}
949
See \exception{WantReadError}. The socket send buffer may be too full to
950
write more data.
951
\end{excdesc}
952
953
\begin{excdesc}{WantX509LookupError}
954
The operation did not complete because an application callback has asked to be
955
called again. The I/O method should be called again later, with the same
956
arguments. Note: This won't occur in this version, as there are no such
957
callbacks in this version.
958
\end{excdesc}
959
960
\begin{excdesc}{SysCallError}
961
The \exception{SysCallError} occurs when there's an I/O error and OpenSSL's
962
error queue does not contain any information. This can mean two things: An
963
error in the transport protocol, or an end of file that violates the protocol.
964
The parameter to the exception is always a pair \code{(\var{errnum},
965
\var{errstr})}.
966
\end{excdesc}
967
968
969
\subsubsection{Context objects \label{openssl-context}}
970
971
Context objects have the following methods:
972
973
\begin{methoddesc}[Context]{check_privatekey}{}
974
Check if the private key (loaded with \method{use_privatekey\optional{_file}})
975
matches the certificate (loaded with \method{use_certificate\optional{_file}}).
976
Returns \code{None} if they match, raises \exception{Error} otherwise.
977
\end{methoddesc}
978
979
\begin{methoddesc}[Context]{get_app_data}{}
980
Retrieve application data as set by \method{set_app_data}.
981
\end{methoddesc}
982
983
\begin{methoddesc}[Context]{get_cert_store}{}
984
Retrieve the certificate store (a X509Store object) that the context uses.
985
This can be used to add "trusted" certificates without using the.
986
\method{load_verify_locations()} method.
987
\end{methoddesc}
988
989
\begin{methoddesc}[Context]{get_timeout}{}
990
Retrieve session timeout, as set by \method{set_timeout}. The default is 300
991
seconds.
992
\end{methoddesc}
993
994
\begin{methoddesc}[Context]{get_verify_depth}{}
995
Retrieve the Context object's verify depth, as set by
996
\method{set_verify_depth}.
997
\end{methoddesc}
998
999
\begin{methoddesc}[Context]{get_verify_mode}{}
1000
Retrieve the Context object's verify mode, as set by \method{set_verify}.
1001
\end{methoddesc}
1002
1003
\begin{methoddesc}[Context]{load_client_ca}{pemfile}
1004
Read a file with PEM-formatted certificates that will be sent to the client
1005
when requesting a client certificate.
1006
\end{methoddesc}
1007
1008
\begin{methoddesc}[Context]{set_client_ca_list}{certificate_authorities}
1009
Replace the current list of preferred certificate signers that would be
1010
sent to the client when requesting a client certificate with the
1011
\var{certificate_authorities} sequence of \class{OpenSSL.crypto.X509Name}s.
1012
1013
\versionadded{0.10}
1014
\end{methoddesc}
1015
1016
\begin{methoddesc}[Context]{add_client_ca}{certificate_authority}
1017
Extract a \class{OpenSSL.crypto.X509Name} from the \var{certificate_authority}
1018
\class{OpenSSL.crypto.X509} certificate and add it to the list of preferred
1019
certificate signers sent to the client when requesting a client certificate.
1020
1021
\versionadded{0.10}
1022
\end{methoddesc}
1023
1024
\begin{methoddesc}[Context]{load_verify_locations}{pemfile, capath}
1025
Specify where CA certificates for verification purposes are located. These
1026
are trusted certificates. Note that the certificates have to be in PEM
1027
format. If capath is passed, it must be a directory prepared using the
1028
\code{c_rehash} tool included with OpenSSL. Either, but not both, of
1029
\var{pemfile} or \var{capath} may be \code{None}.
1030
\end{methoddesc}
1031
1032
\begin{methoddesc}[Context]{set_default_verify_paths}{}
1033
Specify that the platform provided CA certificates are to be used for
1034
verification purposes. This method may not work properly on OS X.
1035
\end{methoddesc}
1036
1037
\begin{methoddesc}[Context]{load_tmp_dh}{dhfile}
1038
Load parameters for Ephemeral Diffie-Hellman from \var{dhfile}.
1039
\end{methoddesc}
1040
1041
\begin{methoddesc}[Context]{set_app_data}{data}
1042
Associate \var{data} with this Context object. \var{data} can be retrieved
1043
later using the \method{get_app_data} method.
1044
\end{methoddesc}
1045
1046
\begin{methoddesc}[Context]{set_cipher_list}{ciphers}
1047
Set the list of ciphers to be used in this context. See the OpenSSL manual for
1048
more information (e.g. ciphers(1))
1049
\end{methoddesc}
1050
1051
\begin{methoddesc}[Context]{set_info_callback}{callback}
1052
Set the information callback to \var{callback}. This function will be called
1053
from time to time during SSL handshakes.
1054
\var{callback} should take three arguments: a Connection object and two
1055
integers. The first integer specifies where in the SSL handshake the function
1056
was called, and the other the return code from a (possibly failed) internal
1057
function call.
1058
\end{methoddesc}
1059
1060
\begin{methoddesc}[Context]{set_options}{options}
1061
Add SSL options. Options you have set before are not cleared!
1062
This method should be used with the \constant{OP_*} constants.
1063
\end{methoddesc}
1064
1065
\begin{methoddesc}[Context]{set_mode}{mode}
1066
Add SSL mode. Modes you have set before are not cleared!
1067
This method should be used with the \constant{MODE_*} constants.
1068
\end{methoddesc}
1069
1070
\begin{methoddesc}[Context]{set_passwd_cb}{callback\optional{, userdata}}
1071
Set the passphrase callback to \var{callback}. This function will be called
1072
when a private key with a passphrase is loaded. \var{callback} must accept
1073
three positional arguments. First, an integer giving the maximum length of
1074
the passphrase it may return. If the returned passphrase is longer than
1075
this, it will be truncated. Second, a boolean value which will be true if
1076
the user should be prompted for the passphrase twice and the callback should
1077
verify that the two values supplied are equal. Third, the value given as the
1078
\var{userdata} parameter to \method{set_passwd_cb}. If an error occurs,
1079
\var{callback} should return a false value (e.g. an empty string).
1080
\end{methoddesc}
1081
1082
\begin{methoddesc}[Context]{set_session_id}{name}
1083
Set the context \var{name} within which a session can be reused for this
1084
Context object. This is needed when doing session resumption, because there is
1085
no way for a stored session to know which Context object it is associated with.
1086
\var{name} may be any binary data.
1087
\end{methoddesc}
1088
1089
\begin{methoddesc}[Context]{set_timeout}{timeout}
1090
Set the timeout for newly created sessions for this Context object to
1091
\var{timeout}. \var{timeout} must be given in (whole) seconds. The default
1092
value is 300 seconds. See the OpenSSL manual for more information (e.g.
1093
SSL_CTX_set_timeout(3)).
1094
\end{methoddesc}
1095
1096
\begin{methoddesc}[Context]{set_verify}{mode, callback}
1097
Set the verification flags for this Context object to \var{mode} and specify
1098
that \var{callback} should be used for verification callbacks. \var{mode}
1099
should be one of \constant{VERIFY_NONE} and \constant{VERIFY_PEER}. If
1100
\constant{VERIFY_PEER} is used, \var{mode} can be OR:ed with
1101
\constant{VERIFY_FAIL_IF_NO_PEER_CERT} and \constant{VERIFY_CLIENT_ONCE} to
1102
further control the behaviour.
1103
\var{callback} should take five arguments: A Connection object, an X509 object,
1104
and three integer variables, which are in turn potential error number, error
1105
depth and return code. \var{callback} should return true if verification passes
1106
and false otherwise.
1107
\end{methoddesc}
1108
1109
\begin{methoddesc}[Context]{set_verify_depth}{depth}
1110
Set the maximum depth for the certificate chain verification that shall be
1111
allowed for this Context object.
1112
\end{methoddesc}
1113
1114
\begin{methoddesc}[Context]{use_certificate}{cert}
1115
Use the certificate \var{cert} which has to be a X509 object.
1116
\end{methoddesc}
1117
1118
\begin{methoddesc}[Context]{add_extra_chain_cert}{cert}
1119
Adds the certificate \var{cert}, which has to be a X509 object, to the
1120
certificate chain presented together with the certificate.
1121
\end{methoddesc}
1122
1123
\begin{methoddesc}[Context]{use_certificate_chain_file}{file}
1124
Load a certificate chain from \var{file} which must be PEM encoded.
1125
\end{methoddesc}
1126
1127
\begin{methoddesc}[Context]{use_privatekey}{pkey}
1128
Use the private key \var{pkey} which has to be a PKey object.
1129
\end{methoddesc}
1130
1131
\begin{methoddesc}[Context]{use_certificate_file}{file\optional{, format}}
1132
Load the first certificate found in \var{file}. The certificate must be in the
1133
format specified by \var{format}, which is either \constant{FILETYPE_PEM} or
1134
\constant{FILETYPE_ASN1}. The default is \constant{FILETYPE_PEM}.
1135
\end{methoddesc}
1136
1137
\begin{methoddesc}[Context]{use_privatekey_file}{file\optional{, format}}
1138
Load the first private key found in \var{file}. The private key must be in the
1139
format specified by \var{format}, which is either \constant{FILETYPE_PEM} or
1140
\constant{FILETYPE_ASN1}. The default is \constant{FILETYPE_PEM}.
1141
\end{methoddesc}
1142
1143
\begin{methoddesc}[Context]{set_tlsext_servername_callback}{callback}
1144
Specify a one-argument callable to use as the TLS extension server name
1145
callback. When a connection using the server name extension is made using this
1146
context, the callback will be invoked with the \code{Connection} instance.
1147
\versionadded{0.13}
1148
\end{methoddesc}
1149
1150
\subsubsection{Connection objects \label{openssl-connection}}
1151
1152
Connection objects have the following methods:
1153
1154
\begin{methoddesc}[Connection]{accept}{}
1155
Call the \method{accept} method of the underlying socket and set up SSL on the
1156
returned socket, using the Context object supplied to this Connection object at
1157
creation. Returns a pair \code{(\var{conn}, \var{address})}. where \var{conn}
1158
is the new Connection object created, and \var{address} is as returned by the
1159
socket's \method{accept}.
1160
\end{methoddesc}
1161
1162
\begin{methoddesc}[Connection]{bind}{address}
1163
Call the \method{bind} method of the underlying socket.
1164
\end{methoddesc}
1165
1166
\begin{methoddesc}[Connection]{close}{}
1167
Call the \method{close} method of the underlying socket. Note: If you want
1168
correct SSL closure, you need to call the \method{shutdown} method first.
1169
\end{methoddesc}
1170
1171
\begin{methoddesc}[Connection]{connect}{address}
1172
Call the \method{connect} method of the underlying socket and set up SSL on the
1173
socket, using the Context object supplied to this Connection object at
1174
creation.
1175
\end{methoddesc}
1176
1177
\begin{methoddesc}[Connection]{connect_ex}{address}
1178
Call the \method{connect_ex} method of the underlying socket and set up SSL on
1179
the socket, using the Context object supplied to this Connection object at
1180
creation. Note that if the \method{connect_ex} method of the socket doesn't
1181
return 0, SSL won't be initialized.
1182
\end{methoddesc}
1183
1184
\begin{methoddesc}[Connection]{do_handshake}{}
1185
Perform an SSL handshake (usually called after \method{renegotiate} or one of
1186
\method{set_accept_state} or \method{set_accept_state}). This can raise the
1187
same exceptions as \method{send} and \method{recv}.
1188
\end{methoddesc}
1189
1190
\begin{methoddesc}[Connection]{fileno}{}
1191
Retrieve the file descriptor number for the underlying socket.
1192
\end{methoddesc}
1193
1194
\begin{methoddesc}[Connection]{listen}{backlog}
1195
Call the \method{listen} method of the underlying socket.
1196
\end{methoddesc}
1197
1198
\begin{methoddesc}[Connection]{get_app_data}{}
1199
Retrieve application data as set by \method{set_app_data}.
1200
\end{methoddesc}
1201
1202
\begin{methoddesc}[Connection]{get_cipher_list}{}
1203
Retrieve the list of ciphers used by the Connection object. WARNING: This API
1204
has changed. It used to take an optional parameter and just return a string,
1205
but not it returns the entire list in one go.
1206
\end{methoddesc}
1207
1208
\begin{methoddesc}[Connection]{get_client_ca_list}{}
1209
Retrieve the list of preferred client certificate issuers sent by the server
1210
as \class{OpenSSL.crypto.X509Name} objects.
1211
1212
If this is a client \class{Connection}, the list will be empty until the
1213
connection with the server is established.
1214
1215
If this is a server \class{Connection}, return the list of certificate
1216
authorities that will be sent or has been sent to the client, as controlled
1217
by this \class{Connection}'s \class{Context}.
1218
1219
\versionadded{0.10}
1220
\end{methoddesc}
1221
1222
\begin{methoddesc}[Connection]{get_context}{}
1223
Retrieve the Context object associated with this Connection.
1224
\end{methoddesc}
1225
1226
\begin{methoddesc}[Connection]{set_context}{context}
1227
Specify a replacement Context object for this Connection.
1228
\end{methoddesc}
1229
1230
\begin{methoddesc}[Connection]{get_peer_certificate}{}
1231
Retrieve the other side's certificate (if any)
1232
\end{methoddesc}
1233
1234
\begin{methoddesc}[Connection]{get_peer_cert_chain}{}
1235
Retrieve the tuple of the other side's certificate chain (if any)
1236
\end{methoddesc}
1237
1238
\begin{methoddesc}[Connection]{getpeername}{}
1239
Call the \method{getpeername} method of the underlying socket.
1240
\end{methoddesc}
1241
1242
\begin{methoddesc}[Connection]{getsockname}{}
1243
Call the \method{getsockname} method of the underlying socket.
1244
\end{methoddesc}
1245
1246
\begin{methoddesc}[Connection]{getsockopt}{level, optname\optional{, buflen}}
1247
Call the \method{getsockopt} method of the underlying socket.
1248
\end{methoddesc}
1249
1250
\begin{methoddesc}[Connection]{pending}{}
1251
Retrieve the number of bytes that can be safely read from the SSL buffer
1252
(\emph{not} the underlying transport buffer).
1253
\end{methoddesc}
1254
1255
\begin{methoddesc}[Connection]{recv}{bufsize}
1256
Receive data from the Connection. The return value is a string representing the
1257
data received. The maximum amount of data to be received at once, is specified
1258
by \var{bufsize}.
1259
\end{methoddesc}
1260
1261
\begin{methoddesc}[Connection]{bio_write}{bytes}
1262
If the Connection was created with a memory BIO, this method can be used to add
1263
bytes to the read end of that memory BIO. The Connection can then read the
1264
bytes (for example, in response to a call to \method{recv}).
1265
\end{methoddesc}
1266
1267
\begin{methoddesc}[Connection]{renegotiate}{}
1268
Renegotiate the SSL session. Call this if you wish to change cipher suites or
1269
anything like that.
1270
\end{methoddesc}
1271
1272
\begin{methoddesc}[Connection]{send}{string}
1273
Send the \var{string} data to the Connection.
1274
\end{methoddesc}
1275
1276
\begin{methoddesc}[Connection]{bio_read}{bufsize}
1277
If the Connection was created with a memory BIO, this method can be used to
1278
read bytes from the write end of that memory BIO. Many Connection methods will
1279
add bytes which must be read in this manner or the buffer will eventually fill
1280
up and the Connection will be able to take no further actions.
1281
\end{methoddesc}
1282
1283
\begin{methoddesc}[Connection]{sendall}{string}
1284
Send all of the \var{string} data to the Connection. This calls \method{send}
1285
repeatedly until all data is sent. If an error occurs, it's impossible to tell
1286
how much data has been sent.
1287
\end{methoddesc}
1288
1289
\begin{methoddesc}[Connection]{set_accept_state}{}
1290
Set the connection to work in server mode. The handshake will be handled
1291
automatically by read/write.
1292
\end{methoddesc}
1293
1294
\begin{methoddesc}[Connection]{set_app_data}{data}
1295
Associate \var{data} with this Connection object. \var{data} can be retrieved
1296
later using the \method{get_app_data} method.
1297
\end{methoddesc}
1298
1299
\begin{methoddesc}[Connection]{set_connect_state}{}
1300
Set the connection to work in client mode. The handshake will be handled
1301
automatically by read/write.
1302
\end{methoddesc}
1303
1304
\begin{methoddesc}[Connection]{setblocking}{flag}
1305
Call the \method{setblocking} method of the underlying socket.
1306
\end{methoddesc}
1307
1308
\begin{methoddesc}[Connection]{setsockopt}{level, optname, value}
1309
Call the \method{setsockopt} method of the underlying socket.
1310
\end{methoddesc}
1311
1312
\begin{methoddesc}[Connection]{shutdown}{}
1313
Send the shutdown message to the Connection. Returns true if the shutdown
1314
message exchange is completed and false otherwise (in which case you call
1315
\method{recv()} or \method{send()} when the connection becomes
1316
readable/writeable.
1317
\end{methoddesc}
1318
1319
\begin{methoddesc}[Connection]{get_shutdown}{}
1320
Get the shutdown state of the Connection. Returns a bitvector of either or
1321
both of \var{SENT_SHUTDOWN} and \var{RECEIVED_SHUTDOWN}.
1322
\end{methoddesc}
1323
1324
\begin{methoddesc}[Connection]{set_shutdown}{state}
1325
Set the shutdown state of the Connection. \var{state} is a bitvector of
1326
either or both of \var{SENT_SHUTDOWN} and \var{RECEIVED_SHUTDOWN}.
1327
\end{methoddesc}
1328
1329
\begin{methoddesc}[Connection]{sock_shutdown}{how}
1330
Call the \method{shutdown} method of the underlying socket.
1331
\end{methoddesc}
1332
1333
\begin{methoddesc}[Connection]{bio_shutdown}{}
1334
If the Connection was created with a memory BIO, this method can be used to
1335
indicate that ``end of file'' has been reached on the read end of that memory
1336
BIO.
1337
\end{methoddesc}
1338
1339
\begin{methoddesc}[Connection]{state_string}{}
1340
Retrieve a verbose string detailing the state of the Connection.
1341
\end{methoddesc}
1342
1343
\begin{methoddesc}[Connection]{client_random}{}
1344
Retrieve the random value used with the client hello message.
1345
\end{methoddesc}
1346
1347
\begin{methoddesc}[Connection]{server_random}{}
1348
Retrieve the random value used with the server hello message.
1349
\end{methoddesc}
1350
1351
\begin{methoddesc}[Connection]{master_key}{}
1352
Retrieve the value of the master key for this session.
1353
\end{methoddesc}
1354
1355
\begin{methoddesc}[Connection]{want_read}{}
1356
Checks if more data has to be read from the transport layer to complete an
1357
operation.
1358
\end{methoddesc}
1359
1360
\begin{methoddesc}[Connection]{want_write}{}
1361
Checks if there is data to write to the transport layer to complete an
1362
operation.
1363
\end{methoddesc}
1364
1365
\begin{methoddesc}[Connection]{set_tlsext_host_name}{name}
1366
Specify the byte string to send as the server name in the client hello message.
1367
\versionadded{0.13}
1368
\end{methoddesc}
1369
1370
\begin{methoddesc}[Connection]{get_servername}{}
1371
Get the value of the server name received in the client hello message.
1372
\versionadded{0.13}
1373
\end{methoddesc}
1374
1375
1376
1377
\section{Internals \label{internals}}
1378
1379
We ran into three main problems developing this: Exceptions, callbacks and
1380
accessing socket methods. This is what this chapter is about.
1381
1382
\subsection{Exceptions \label{exceptions}}
1383
1384
We realized early that most of the exceptions would be raised by the I/O
1385
functions of OpenSSL, so it felt natural to mimic OpenSSL's error code system,
1386
translating them into Python exceptions. This naturally gives us the exceptions
1387
\exception{SSL.ZeroReturnError}, \exception{SSL.WantReadError},
1388
\exception{SSL.WantWriteError}, \exception{SSL.WantX509LookupError} and
1389
\exception{SSL.SysCallError}.
1390
1391
For more information about this, see section \ref{openssl-ssl}.
1392
1393
1394
\subsection{Callbacks \label{callbacks}}
1395
1396
There are a number of problems with callbacks. First of all, OpenSSL is written
1397
as a C library, it's not meant to have Python callbacks, so a way around that
1398
is needed. Another problem is thread support. A lot of the OpenSSL I/O
1399
functions can block if the socket is in blocking mode, and then you want other
1400
Python threads to be able to do other things. The real trouble is if you've
1401
released the global CPython interpreter lock to do a potentially blocking
1402
operation, and the operation calls a callback. Then we must take the GIL back,
1403
since calling Python APIs without holding it is not allowed.
1404
1405
There are two solutions to the first problem, both of which are necessary. The
1406
first solution to use is if the C callback allows ''userdata'' to be passed to
1407
it (an arbitrary pointer normally). This is great! We can set our Python
1408
function object as the real userdata and emulate userdata for the Python
1409
function in another way. The other solution can be used if an object with an
1410
''app_data'' system always is passed to the callback. For example, the SSL
1411
object in OpenSSL has app_data functions and in e.g. the verification
1412
callbacks, you can retrieve the related SSL object. What we do is to set our
1413
wrapper \class{Connection} object as app_data for the SSL object, and we can
1414
easily find the Python callback.
1415
1416
The other problem is solved using thread local variables. Whenever the GIL is
1417
released before calling into an OpenSSL API, the PyThreadState pointer returned
1418
by \cfunction{PyEval_SaveState} is stored in a global thread local variable
1419
(using Python's own TLS API, \cfunction{PyThread_set_key_value}). When it is
1420
necessary to re-acquire the GIL, either after the OpenSSL API returns or in a C
1421
callback invoked by that OpenSSL API, the value of the thread local variable is
1422
retrieved (\cfunction{PyThread_get_key_value}) and used to re-acquire the GIL.
1423
This allows Python threads to execute while OpenSSL APIs are running and allows
1424
use of any particular pyOpenSSL object from any Python thread, since there is
1425
no per-thread state associated with any of these objects and since OpenSSL is
1426
threadsafe (as long as properly initialized, as pyOpenSSL initializes it).
1427
1428
1429
\subsection{Acessing Socket Methods \label{socket-methods}}
1430
1431
We quickly saw the benefit of wrapping socket methods in the
1432
\class{SSL.Connection} class, for an easy transition into using SSL. The
1433
problem here is that the \module{socket} module lacks a C API, and all the
1434
methods are declared static. One approach would be to have \module{OpenSSL} as
1435
a submodule to the \module{socket} module, placing all the code in
1436
\file{socketmodule.c}, but this is obviously not a good solution, since you
1437
might not want to import tonnes of extra stuff you're not going to use when
1438
importing the \module{socket} module. The other approach is to somehow get a
1439
pointer to the method to be called, either the C function, or a callable Python
1440
object. This is not really a good solution either, since there's a lot of
1441
lookups involved.
1442
1443
The way it works is that you have to supply a ``\class{socket}-like'' transport
1444
object to the \class{SSL.Connection}. The only requirement of this object is
1445
that it has a \method{fileno()} method that returns a file descriptor that's
1446
valid at the C level (i.e. you can use the system calls read and write). If you
1447
want to use the \method{connect()} or \method{accept()} methods of the
1448
\class{SSL.Connection} object, the transport object has to supply such
1449
methods too. Apart from them, any method lookups in the \class{SSL.Connection}
1450
object that fail are passed on to the underlying transport object.
1451
1452
Future changes might be to allow Python-level transport objects, that instead
1453
of having \method{fileno()} methods, have \method{read()} and \method{write()}
1454
methods, so more advanced features of Python can be used. This would probably
1455
entail some sort of OpenSSL ``BIOs'', but converting Python strings back and
1456
forth is expensive, so this shouldn't be used unless necessary. Other nice
1457
things would be to be able to pass in different transport objects for reading
1458
and writing, but then the \method{fileno()} method of \class{SSL.Connection}
1459
becomes virtually useless. Also, should the method resolution be used on the
1460
read-transport or the write-transport?
1461
1462
1463
\end{document}
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