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Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001\documentclass{howto}
2
3\title{Python OpenSSL Manual}
4
Jean-Paul Calderone71ff3682009-04-25 08:30:11 -04005\release{0.9}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05006
Jean-Paul Calderone0ebe45a2009-04-25 10:40:31 -04007\author{Jean-Paul Calderone}
8\authoraddress{\email{exarkun@twistedmatrix.com}}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05009
10\usepackage[english]{babel}
11\usepackage[T1]{fontenc}
12
13\begin{document}
14
15\maketitle
16
17\begin{abstract}
18\noindent
19This module is a rather thin wrapper around (a subset of) the OpenSSL library.
20With thin wrapper I mean that a lot of the object methods do nothing more than
21calling a corresponding function in the OpenSSL library.
22\end{abstract}
23
24\tableofcontents
25
26
27\section{Introduction \label{intro}}
28
Jean-Paul Calderone9450d5b2008-09-01 12:04:20 -040029The reason pyOpenSSL was created is that the SSL support in the socket module
30in Python 2.1 (the contemporary version of Python when the pyOpenSSL project
31was begun) was severely limited. Other OpenSSL wrappers for Python at the time
32were also limited, though in different ways. Unfortunately, Python's standard
33library SSL support has remained weak, although other packages (such as
34M2Crypto\footnote{See \url{http://chandlerproject.org/Projects/MeTooCrypto}})
35have made great advances and now equal or exceed pyOpenSSL's functionality.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -050036
Jean-Paul Calderone9450d5b2008-09-01 12:04:20 -040037The reason pyOpenSSL continues to be maintained is that there is a significant
38user community around it, as well as a large amount of software which depends
39on it. It is a great benefit to many people for pyOpenSSL to continue to exist
40and advance.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -050041
42\section{Building and Installing \label{building}}
43
44These instructions can also be found in the file \verb|INSTALL|.
45
46I have tested this on Debian Linux systems (woody and sid), Solaris 2.6 and
472.7. Others have successfully compiled it on Windows and NT.
48
49\subsection{Building the Module on a Unix System \label{building-unix}}
50
51pyOpenSSL uses distutils, so there really shouldn't be any problems. To build
52the library:
53\begin{verbatim}
54python setup.py build
55\end{verbatim}
56
57If your OpenSSL header files aren't in \verb|/usr/include|, you may need to
58supply the \verb|-I| flag to let the setup script know where to look. The same
59goes for the libraries of course, use the \verb|-L| flag. Note that
60\verb|build| won't accept these flags, so you have to run first
61\verb|build_ext| and then \verb|build|! Example:
62\begin{verbatim}
63python setup.py build_ext -I/usr/local/ssl/include -L/usr/local/ssl/lib
64python setup.py build
65\end{verbatim}
66
67Now you should have a directory called \verb|OpenSSL| that contains e.g.
68\verb|SSL.so| and \verb|__init__.py| somewhere in the build dicrectory,
69so just:
70\begin{verbatim}
71python setup.py install
72\end{verbatim}
73
74If you, for some arcane reason, don't want the module to appear in the
75\verb|site-packages| directory, use the \verb|--prefix| option.
76
77You can, of course, do
78\begin{verbatim}
79python setup.py --help
80\end{verbatim}
81
82to find out more about how to use the script.
83
84\subsection{Building the Module on a Windows System \label{building-windows}}
85
86Big thanks to Itamar Shtull-Trauring and Oleg Orlov for their help with
87Windows build instructions. Same as for Unix systems, we have to separate
88the \verb|build_ext| and the \verb|build|.
89
90Building the library:
91
92\begin{verbatim}
93setup.py build_ext -I ...\openssl\inc32 -L ...\openssl\out32dll
94setup.py build
95\end{verbatim}
96
97Where \verb|...\openssl| is of course the location of your OpenSSL installation.
98
99Installation is the same as for Unix systems:
100\begin{verbatim}
101setup.py install
102\end{verbatim}
103
104And similarily, you can do
105\begin{verbatim}
106setup.py --help
107\end{verbatim}
108
109to get more information.
110
111
112\section{\module{OpenSSL} --- Python interface to OpenSSL \label{openssl}}
113
114\declaremodule{extension}{OpenSSL}
115\modulesynopsis{Python interface to OpenSSL}
116
117This package provides a high-level interface to the functions in the
118OpenSSL library. The following modules are defined:
119
120\begin{datadesc}{crypto}
121Generic cryptographic module. Note that if anything is incomplete, this module is!
122\end{datadesc}
123
124\begin{datadesc}{rand}
125An interface to the OpenSSL pseudo random number generator.
126\end{datadesc}
127
128\begin{datadesc}{SSL}
129An interface to the SSL-specific parts of OpenSSL.
130\end{datadesc}
131
132
133% % % crypto moduleOpenSSL
134
135\subsection{\module{crypto} --- Generic cryptographic module \label{openssl-crypto}}
136
137\declaremodule{extension}{crypto}
138\modulesynopsis{Generic cryptographic module}
139
140\begin{datadesc}{X509Type}
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400141See \class{X509}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500142\end{datadesc}
143
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400144\begin{classdesc}{X509}{}
145A class representing X.509 certificates.
146\end{classdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500147
148\begin{datadesc}{X509NameType}
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400149See \class{X509Name}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500150\end{datadesc}
151
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400152\begin{classdesc}{X509Name}{x509name}
153A class representing X.509 Distinguished Names.
154
155This constructor creates a copy of \var{x509name} which should be an
156instance of \class{X509Name}.
157\end{classdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500158
159\begin{datadesc}{X509ReqType}
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400160See \class{X509Req}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500161\end{datadesc}
162
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400163\begin{classdesc}{X509Req}{}
164A class representing X.509 certificate requests.
165\end{classdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500166
167\begin{datadesc}{X509StoreType}
168A Python type object representing the X509Store object type.
169\end{datadesc}
170
171\begin{datadesc}{PKeyType}
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400172See \class{PKey}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500173\end{datadesc}
174
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400175\begin{classdesc}{PKey}{}
176A class representing DSA or RSA keys.
177\end{classdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500178
179\begin{datadesc}{PKCS7Type}
180A Python type object representing the PKCS7 object type.
181\end{datadesc}
182
183\begin{datadesc}{PKCS12Type}
184A Python type object representing the PKCS12 object type.
185\end{datadesc}
186
187\begin{datadesc}{X509ExtensionType}
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400188See \class{X509Extension}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500189\end{datadesc}
190
Rick Dean47262da2009-07-08 16:17:17 -0500191\begin{classdesc}{X509Extension}{typename, critical, value\optional{, subject}\optional{, issuer}}
192A class representing an X.509 v3 certificate extensions.
193See \url{http://openssl.org/docs/apps/x509v3_config.html\#STANDARD_EXTENSIONS}
194for \var{typename} strings and their options.
195Optional parameters \var{subject} and \var{issuer} must be X509 objects.
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400196\end{classdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500197
198\begin{datadesc}{NetscapeSPKIType}
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400199See \class{NetscapeSPKI}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500200\end{datadesc}
201
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400202\begin{classdesc}{NetscapeSPKI}{\optional{enc}}
203A class representing Netscape SPKI objects.
204
205If the \var{enc} argument is present, it should be a base64-encoded string
206representing a NetscapeSPKI object, as returned by the \method{b64_encode}
207method.
208\end{classdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500209
210\begin{datadesc}{FILETYPE_PEM}
211\dataline{FILETYPE_ASN1}
212File type constants.
213\end{datadesc}
214
215\begin{datadesc}{TYPE_RSA}
216\dataline{TYPE_DSA}
217Key type constants.
218\end{datadesc}
219
220\begin{excdesc}{Error}
221Generic exception used in the \module{crypto} module.
222\end{excdesc}
223
224\begin{funcdesc}{dump_certificate}{type, cert}
225Dump the certificate \var{cert} into a buffer string encoded with the type
226\var{type}.
227\end{funcdesc}
228
229\begin{funcdesc}{dump_certificate_request}{type, req}
230Dump the certificate request \var{req} into a buffer string encoded with the
231type \var{type}.
232\end{funcdesc}
233
234\begin{funcdesc}{dump_privatekey}{type, pkey\optional{, cipher, passphrase}}
235Dump the private key \var{pkey} into a buffer string encoded with the type
236\var{type}, optionally (if \var{type} is \constant{FILETYPE_PEM}) encrypting it
237using \var{cipher} and \var{passphrase}.
238
239\var{passphrase} must be either a string or a callback for providing the
240pass phrase.
241\end{funcdesc}
242
243\begin{funcdesc}{load_certificate}{type, buffer}
244Load a certificate (X509) from the string \var{buffer} encoded with the
245type \var{type}.
246\end{funcdesc}
247
248\begin{funcdesc}{load_certificate_request}{type, buffer}
249Load a certificate request (X509Req) from the string \var{buffer} encoded with
250the type \var{type}.
251\end{funcdesc}
252
253\begin{funcdesc}{load_privatekey}{type, buffer\optional{, passphrase}}
254Load a private key (PKey) from the string \var{buffer} encoded with
255the type \var{type} (must be one of \constant{FILETYPE_PEM} and
256\constant{FILETYPE_ASN1}).
257
258\var{passphrase} must be either a string or a callback for providing the
259pass phrase.
260\end{funcdesc}
261
262\begin{funcdesc}{load_pkcs7_data}{type, buffer}
263Load pkcs7 data from the string \var{buffer} encoded with the type \var{type}.
264\end{funcdesc}
265
266\begin{funcdesc}{load_pkcs12}{buffer\optional{, passphrase}}
267Load pkcs12 data from the string \var{buffer}. If the pkcs12 structure is
268encrypted, a \var{passphrase} must be included.
269\end{funcdesc}
270
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500271\subsubsection{X509 objects \label{openssl-x509}}
272
273X509 objects have the following methods:
274
275\begin{methoddesc}[X509]{get_issuer}{}
Jean-Paul Calderone2aa2b332008-03-06 21:43:14 -0500276Return an X509Name object representing the issuer of the certificate.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500277\end{methoddesc}
278
279\begin{methoddesc}[X509]{get_pubkey}{}
280Return a PKey object representing the public key of the certificate.
281\end{methoddesc}
282
283\begin{methoddesc}[X509]{get_serial_number}{}
284Return the certificate serial number.
285\end{methoddesc}
286
287\begin{methoddesc}[X509]{get_subject}{}
Jean-Paul Calderone2aa2b332008-03-06 21:43:14 -0500288Return an X509Name object representing the subject of the certificate.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500289\end{methoddesc}
290
291\begin{methoddesc}[X509]{get_version}{}
292Return the certificate version.
293\end{methoddesc}
294
Jean-Paul Calderone525ef802008-03-09 20:39:42 -0400295\begin{methoddesc}[X509]{get_notBefore}{}
296Return a string giving the time before which the certificate is not valid. The
297string is formatted as an ASN1 GENERALIZEDTIME:
298\begin{verbatim}
299 YYYYMMDDhhmmssZ
300 YYYYMMDDhhmmss+hhmm
301 YYYYMMDDhhmmss-hhmm
302\end{verbatim}
Jean-Paul Calderonee0615b52008-03-09 21:44:46 -0400303If no value exists for this field, \code{None} is returned.
Jean-Paul Calderone525ef802008-03-09 20:39:42 -0400304\end{methoddesc}
305
306\begin{methoddesc}[X509]{get_notAfter}{}
307Return a string giving the time after which the certificate is not valid. The
308string is formatted as an ASN1 GENERALIZEDTIME:
309\begin{verbatim}
310 YYYYMMDDhhmmssZ
311 YYYYMMDDhhmmss+hhmm
312 YYYYMMDDhhmmss-hhmm
313\end{verbatim}
Jean-Paul Calderonee0615b52008-03-09 21:44:46 -0400314If no value exists for this field, \code{None} is returned.
Jean-Paul Calderone525ef802008-03-09 20:39:42 -0400315\end{methoddesc}
316
317\begin{methoddesc}[X509]{set_notBefore}{when}
318Change the time before which the certificate is not valid. \var{when} is a
319string formatted as an ASN1 GENERALIZEDTIME:
320\begin{verbatim}
321 YYYYMMDDhhmmssZ
322 YYYYMMDDhhmmss+hhmm
323 YYYYMMDDhhmmss-hhmm
324\end{verbatim}
325\end{methoddesc}
326
327\begin{methoddesc}[X509]{set_notAfter}{when}
328Change the time after which the certificate is not valid. \var{when} is a
329string formatted as an ASN1 GENERALIZEDTIME:
330\begin{verbatim}
331 YYYYMMDDhhmmssZ
332 YYYYMMDDhhmmss+hhmm
333 YYYYMMDDhhmmss-hhmm
334\end{verbatim}
335\end{methoddesc}
336
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500337\begin{methoddesc}[X509]{gmtime_adj_notBefore}{time}
338Adjust the timestamp (in GMT) when the certificate starts being valid.
339\end{methoddesc}
340
341\begin{methoddesc}[X509]{gmtime_adj_notAfter}{time}
342Adjust the timestamp (in GMT) when the certificate stops being valid.
343\end{methoddesc}
344
345\begin{methoddesc}[X509]{has_expired}{}
346Checks the certificate's time stamp against current time. Returns true if the
347certificate has expired and false otherwise.
348\end{methoddesc}
349
350\begin{methoddesc}[X509]{set_issuer}{issuer}
351Set the issuer of the certificate to \var{issuer}.
352\end{methoddesc}
353
354\begin{methoddesc}[X509]{set_pubkey}{pkey}
355Set the public key of the certificate to \var{pkey}.
356\end{methoddesc}
357
358\begin{methoddesc}[X509]{set_serial_number}{serialno}
359Set the serial number of the certificate to \var{serialno}.
360\end{methoddesc}
361
362\begin{methoddesc}[X509]{set_subject}{subject}
363Set the subject of the certificate to \var{subject}.
364\end{methoddesc}
365
366\begin{methoddesc}[X509]{set_version}{version}
367Set the certificate version to \var{version}.
368\end{methoddesc}
369
370\begin{methoddesc}[X509]{sign}{pkey, digest}
371Sign the certificate, using the key \var{pkey} and the message digest algorithm
372identified by the string \var{digest}.
373\end{methoddesc}
374
375\begin{methoddesc}[X509]{subject_name_hash}{}
376Return the hash of the certificate subject.
377\end{methoddesc}
378
379\begin{methoddesc}[X509]{digest}{digest_name}
380Return a digest of the certificate, using the \var{digest_name} method.
Jean-Paul Calderoneb6f0d602008-12-28 21:20:01 -0500381\var{digest_name} must be a string describing a digest algorithm supported
382by OpenSSL (by EVP_get_digestbyname, specifically). For example,
383\constant{"md5"} or \constant{"sha1"}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500384\end{methoddesc}
385
386\begin{methoddesc}[X509]{add_extensions}{extensions}
387Add the extensions in the sequence \var{extensions} to the certificate.
388\end{methoddesc}
389
390\subsubsection{X509Name objects \label{openssl-x509name}}
391
Jean-Paul Calderone2dd8ff52008-03-24 17:43:58 -0400392X509Name objects have the following methods:
393
394\begin{methoddesc}[X509Name]{hash}{}
395Return an integer giving the first four bytes of the MD5 digest of the DER
396representation of the name.
397\end{methoddesc}
398
Jean-Paul Calderonea6edbf82008-03-25 15:19:11 -0400399\begin{methoddesc}[X509Name]{der}{}
400Return a string giving the DER representation of the name.
401\end{methoddesc}
402
Jean-Paul Calderonec54cc182008-03-26 21:11:07 -0400403\begin{methoddesc}[X509Name]{get_components}{}
404Return a list of two-tuples of strings giving the components of the name.
405\end{methoddesc}
406
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500407X509Name objects have the following members:
408
409\begin{memberdesc}[X509Name]{countryName}
410The country of the entity. \code{C} may be used as an alias for
411\code{countryName}.
412\end{memberdesc}
413
414\begin{memberdesc}[X509Name]{stateOrProvinceName}
415The state or province of the entity. \code{ST} may be used as an alias for
416\code{stateOrProvinceName}·
417\end{memberdesc}
418
419\begin{memberdesc}[X509Name]{localityName}
420The locality of the entity. \code{L} may be used as an alias for
421\code{localityName}.
422\end{memberdesc}
423
424\begin{memberdesc}[X509Name]{organizationName}
425The organization name of the entity. \code{O} may be used as an alias for
426\code{organizationName}.
427\end{memberdesc}
428
429\begin{memberdesc}[X509Name]{organizationalUnitName}
430The organizational unit of the entity. \code{OU} may be used as an alias for
431\code{organizationalUnitName}.
432\end{memberdesc}
433
434\begin{memberdesc}[X509Name]{commonName}
435The common name of the entity. \code{CN} may be used as an alias for
436\code{commonName}.
437\end{memberdesc}
438
439\begin{memberdesc}[X509Name]{emailAddress}
440The e-mail address of the entity.
441\end{memberdesc}
442
443\subsubsection{X509Req objects \label{openssl-x509req}}
444
445X509Req objects have the following methods:
446
447\begin{methoddesc}[X509Req]{get_pubkey}{}
448Return a PKey object representing the public key of the certificate request.
449\end{methoddesc}
450
451\begin{methoddesc}[X509Req]{get_subject}{}
Jean-Paul Calderone2aa2b332008-03-06 21:43:14 -0500452Return an X509Name object representing the subject of the certificate.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500453\end{methoddesc}
454
455\begin{methoddesc}[X509Req]{set_pubkey}{pkey}
456Set the public key of the certificate request to \var{pkey}.
457\end{methoddesc}
458
459\begin{methoddesc}[X509Req]{sign}{pkey, digest}
460Sign the certificate request, using the key \var{pkey} and the message digest
461algorithm identified by the string \var{digest}.
462\end{methoddesc}
463
464\begin{methoddesc}[X509Req]{verify}{pkey}
465Verify a certificate request using the public key \var{pkey}.
466\end{methoddesc}
467
Jean-Paul Calderone8dd19b82008-12-28 20:41:16 -0500468\begin{methoddesc}[X509Req]{set_version}{version}
469Set the version (RFC 2459, 4.1.2.1) of the certificate request to
470\var{version}.
471\end{methoddesc}
472
473\begin{methoddesc}[X509Req]{get_version}{}
474Get the version (RFC 2459, 4.1.2.1) of the certificate request.
475\end{methoddesc}
476
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500477\subsubsection{X509Store objects \label{openssl-x509store}}
478
479The X509Store object has currently just one method:
480
481\begin{methoddesc}[X509Store]{add_cert}{cert}
482Add the certificate \var{cert} to the certificate store.
483\end{methoddesc}
484
485\subsubsection{PKey objects \label{openssl-pkey}}
486
487The PKey object has the following methods:
488
489\begin{methoddesc}[PKey]{bits}{}
490Return the number of bits of the key.
491\end{methoddesc}
492
493\begin{methoddesc}[PKey]{generate_key}{type, bits}
494Generate a public/private key pair of the type \var{type} (one of
495\constant{TYPE_RSA} and \constant{TYPE_DSA}) with the size \var{bits}.
496\end{methoddesc}
497
498\begin{methoddesc}[PKey]{type}{}
499Return the type of the key.
500\end{methoddesc}
501
502\subsubsection{PKCS7 objects \label{openssl-pkcs7}}
503
504PKCS7 objects have the following methods:
505
506\begin{methoddesc}[PKCS7]{type_is_signed}{}
507FIXME
508\end{methoddesc}
509
510\begin{methoddesc}[PKCS7]{type_is_enveloped}{}
511FIXME
512\end{methoddesc}
513
514\begin{methoddesc}[PKCS7]{type_is_signedAndEnveloped}{}
515FIXME
516\end{methoddesc}
517
518\begin{methoddesc}[PKCS7]{type_is_data}{}
519FIXME
520\end{methoddesc}
521
522\begin{methoddesc}[PKCS7]{get_type_name}{}
523Get the type name of the PKCS7.
524\end{methoddesc}
525
526\subsubsection{PKCS12 objects \label{openssl-pkcs12}}
527
528PKCS12 objects have the following methods:
529
530\begin{methoddesc}[PKCS12]{get_certificate}{}
531Return certificate portion of the PKCS12 structure.
532\end{methoddesc}
533
534\begin{methoddesc}[PKCS12]{get_privatekey}{}
535Return private key portion of the PKCS12 structure
536\end{methoddesc}
537
538\begin{methoddesc}[PKCS12]{get_ca_certificates}{}
539Return CA certificates within the PKCS12 object as a tuple. Returns
540None if no CA certificates are present.
541\end{methoddesc}
542
543\subsubsection{X509Extension objects \label{openssl-509ext}}
544
Jean-Paul Calderonef8c5fab2008-12-31 15:53:48 -0500545X509Extension objects have several methods:
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500546
547\begin{methoddesc}[X509Extension]{get_critical}{}
548Return the critical field of the extension object.
549\end{methoddesc}
550
Jean-Paul Calderonef8c5fab2008-12-31 15:53:48 -0500551\begin{methoddesc}[X509Extension]{get_short_name}{}
552Return the short type name of the extension object.
553\end{methoddesc}
554
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500555\subsubsection{NetscapeSPKI objects \label{openssl-netscape-spki}}
556
557NetscapeSPKI objects have the following methods:
558
559\begin{methoddesc}[NetscapeSPKI]{b64_encode}{}
560Return a base64-encoded string representation of the object.
561\end{methoddesc}
562
563\begin{methoddesc}[NetscapeSPKI]{get_pubkey}{}
564Return the public key of object.
565\end{methoddesc}
566
567\begin{methoddesc}[NetscapeSPKI]{set_pubkey}{key}
568Set the public key of the object to \var{key}.
569\end{methoddesc}
570
571\begin{methoddesc}[NetscapeSPKI]{sign}{key, digest_name}
Jean-Paul Calderoneb6f0d602008-12-28 21:20:01 -0500572Sign the NetscapeSPKI object using the given \var{key} and
573\var{digest_name}. \var{digest_name} must be a string describing a digest
574algorithm supported by OpenSSL (by EVP_get_digestbyname, specifically). For
575example, \constant{"md5"} or \constant{"sha1"}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500576\end{methoddesc}
577
578\begin{methoddesc}[NetscapeSPKI]{verify}{key}
579Verify the NetscapeSPKI object using the given \var{key}.
580\end{methoddesc}
581
582
583% % % rand module
584
585\subsection{\module{rand} --- An interface to the OpenSSL pseudo random number generator \label{openssl-rand}}
586
587\declaremodule{extension}{rand}
588\modulesynopsis{An interface to the OpenSSL pseudo random number generator}
589
590This module handles the OpenSSL pseudo random number generator (PRNG) and
591declares the following:
592
593\begin{funcdesc}{add}{string, entropy}
594Mix bytes from \var{string} into the PRNG state. The \var{entropy} argument is
595(the lower bound of) an estimate of how much randomness is contained in
596\var{string}, measured in bytes. For more information, see e.g. \rfc{1750}.
597\end{funcdesc}
598
Rick Dean4fd5a4e2009-07-08 12:06:10 -0500599\begin{funcdesc}{bytes}{num_bytes}
Jean-Paul Calderonea45e2b92009-07-08 13:29:58 -0400600Get some random bytes from the PRNG as a string.
601
602This is a wrapper for the C function \function{RAND_bytes}.
Rick Dean4fd5a4e2009-07-08 12:06:10 -0500603\end{funcdesc}
604
Rick Dean433dc642009-07-07 13:11:55 -0500605\begin{funcdesc}{cleanup}{}
Jean-Paul Calderone427c0b32009-07-07 15:43:27 -0400606Erase the memory used by the PRNG.
607
608This is a wrapper for the C function \function{RAND_cleanup}.
Rick Dean433dc642009-07-07 13:11:55 -0500609\end{funcdesc}
610
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500611\begin{funcdesc}{egd}{path\optional{, bytes}}
612Query the Entropy Gathering Daemon\footnote{See
613\url{http://www.lothar.com/tech/crypto/}} on socket \var{path} for \var{bytes}
614bytes of random data and and uses \function{add} to seed the PRNG. The default
615value of \var{bytes} is 255.
616\end{funcdesc}
617
618\begin{funcdesc}{load_file}{path\optional{, bytes}}
619Read \var{bytes} bytes (or all of it, if \var{bytes} is negative) of data from
620the file \var{path} to seed the PRNG. The default value of \var{bytes} is -1.
621\end{funcdesc}
622
623\begin{funcdesc}{screen}{}
624Add the current contents of the screen to the PRNG state.
625Availability: Windows.
626\end{funcdesc}
627
628\begin{funcdesc}{seed}{string}
629This is equivalent to calling \function{add} with \var{entropy} as the length
630of the string.
631\end{funcdesc}
632
633\begin{funcdesc}{status}{}
634Returns true if the PRNG has been seeded with enough data, and false otherwise.
635\end{funcdesc}
636
637\begin{funcdesc}{write_file}{path}
638Write a number of random bytes (currently 1024) to the file \var{path}. This
639file can then be used with \function{load_file} to seed the PRNG again.
640\end{funcdesc}
641
Rick Deanfc69c812009-07-08 11:03:47 -0500642\begin{excdesc}{Error}
643If the current RAND method supports any errors, this is raised when needed.
644The default method does not raise this when the entropy pool is depleted.
645
646Whenever this exception is raised directly, it has a list of error messages
647from the OpenSSL error queue, where each item is a tuple \code{(\var{lib},
648\var{function}, \var{reason})}. Here \var{lib}, \var{function} and \var{reason}
649are all strings, describing where and what the problem is. See \manpage{err}{3}
650for more information.
651\end{excdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500652
653
654% % % SSL module
655
656\subsection{\module{SSL} --- An interface to the SSL-specific parts of OpenSSL \label{openssl-ssl}}
657
658\declaremodule{extension}{SSL}
659\modulesynopsis{An interface to the SSL-specific parts of OpenSSL}
660
661This module handles things specific to SSL. There are two objects defined:
662Context, Connection.
663
664\begin{datadesc}{SSLv2_METHOD}
665\dataline{SSLv3_METHOD}
666\dataline{SSLv23_METHOD}
667\dataline{TLSv1_METHOD}
668These constants represent the different SSL methods to use when creating a
669context object.
670\end{datadesc}
671
672\begin{datadesc}{VERIFY_NONE}
673\dataline{VERIFY_PEER}
674\dataline{VERIFY_FAIL_IF_NO_PEER_CERT}
675These constants represent the verification mode used by the Context
676object's \method{set_verify} method.
677\end{datadesc}
678
679\begin{datadesc}{FILETYPE_PEM}
680\dataline{FILETYPE_ASN1}
681File type constants used with the \method{use_certificate_file} and
682\method{use_privatekey_file} methods of Context objects.
683\end{datadesc}
684
685\begin{datadesc}{OP_SINGLE_DH_USE}
686\dataline{OP_EPHEMERAL_RSA}
687\dataline{OP_NO_SSLv2}
688\dataline{OP_NO_SSLv3}
689\dataline{OP_NO_TLSv1}
690Constants used with \method{set_options} of Context objects.
691\constant{OP_SINGLE_DH_USE} means to always create a new key when using ephemeral
692Diffie-Hellman. \constant{OP_EPHEMERAL_RSA} means to always use ephemeral RSA keys
693when doing RSA operations. \constant{OP_NO_SSLv2}, \constant{OP_NO_SSLv3} and
694\constant{OP_NO_TLSv1} means to disable those specific protocols. This is
695interesting if you're using e.g. \constant{SSLv23_METHOD} to get an SSLv2-compatible
696handshake, but don't want to use SSLv2.
697\end{datadesc}
698
699\begin{datadesc}{ContextType}
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400700See \class{Context}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500701\end{datadesc}
702
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400703\begin{classdesc}{Context}{method}
704A class representing SSL contexts. Contexts define the parameters of one or
705more SSL connections.
706
707\var{method} should be \constant{SSLv2_METHOD}, \constant{SSLv3_METHOD},
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500708\constant{SSLv23_METHOD} or \constant{TLSv1_METHOD}.
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400709\end{classdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500710
711\begin{datadesc}{ConnectionType}
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400712See \class{Connection}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500713\end{datadesc}
714
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400715\begin{classdesc}{Connection}{context, socket}
716A class representing SSL connections.
717
718\var{context} should be an instance of \class{Context} and \var{socket}
719should be a socket \footnote{Actually, all that is required is an object
720that \emph{behaves} like a socket, you could even use files, even though
721it'd be tricky to get the handshakes right!} object. \var{socket} may be
722\var{None}; in this case, the Connection is created with a memory BIO: see
723the \method{bio_read}, \method{bio_write}, and \method{bio_shutdown}
724methods.
725\end{classdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500726
727\begin{excdesc}{Error}
728This exception is used as a base class for the other SSL-related
729exceptions, but may also be raised directly.
730
731Whenever this exception is raised directly, it has a list of error messages
732from the OpenSSL error queue, where each item is a tuple \code{(\var{lib},
733\var{function}, \var{reason})}. Here \var{lib}, \var{function} and \var{reason}
734are all strings, describing where and what the problem is. See \manpage{err}{3}
735for more information.
736\end{excdesc}
737
738\begin{excdesc}{ZeroReturnError}
739This exception matches the error return code \code{SSL_ERROR_ZERO_RETURN}, and
740is raised when the SSL Connection has been closed. In SSL 3.0 and TLS 1.0, this
741only occurs if a closure alert has occurred in the protocol, i.e. the
742connection has been closed cleanly. Note that this does not necessarily
743mean that the transport layer (e.g. a socket) has been closed.
744
745It may seem a little strange that this is an exception, but it does match an
746\code{SSL_ERROR} code, and is very convenient.
747\end{excdesc}
748
749\begin{excdesc}{WantReadError}
750The operation did not complete; the same I/O method should be called again
751later, with the same arguments. Any I/O method can lead to this since new
752handshakes can occur at any time.
Rick Dean71fa0962009-07-09 23:56:39 -0500753
Jean-Paul Calderonecc787d52009-07-16 12:08:41 -0400754The wanted read is for \emph{dirty} data sent over the network, not the
755\emph{clean} data inside the tunnel. For a socket based SSL connection,
756\emph{read} means data coming at us over the network. Until that read
757succeeds, the attempted \method{OpenSSL.SSL.Connection.recv},
Rick Dean71fa0962009-07-09 23:56:39 -0500758\method{OpenSSL.SSL.Connection.send}, or
Jean-Paul Calderonecc787d52009-07-16 12:08:41 -0400759\method{OpenSSL.SSL.Connection.do_handshake} is prevented or incomplete. You
760probably want to \method{select()} on the socket before trying again.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500761\end{excdesc}
762
763\begin{excdesc}{WantWriteError}
Jean-Paul Calderonecc787d52009-07-16 12:08:41 -0400764See \exception{WantReadError}. The socket send buffer may be too full to
Rick Dean71fa0962009-07-09 23:56:39 -0500765write more data.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500766\end{excdesc}
767
768\begin{excdesc}{WantX509LookupError}
769The operation did not complete because an application callback has asked to be
770called again. The I/O method should be called again later, with the same
771arguments. Note: This won't occur in this version, as there are no such
772callbacks in this version.
773\end{excdesc}
774
775\begin{excdesc}{SysCallError}
776The \exception{SysCallError} occurs when there's an I/O error and OpenSSL's
777error queue does not contain any information. This can mean two things: An
778error in the transport protocol, or an end of file that violates the protocol.
779The parameter to the exception is always a pair \code{(\var{errnum},
780\var{errstr})}.
781\end{excdesc}
782
783
784\subsubsection{Context objects \label{openssl-context}}
785
786Context objects have the following methods:
787
788\begin{methoddesc}[Context]{check_privatekey}{}
789Check if the private key (loaded with \method{use_privatekey\optional{_file}})
790matches the certificate (loaded with \method{use_certificate\optional{_file}}).
Jean-Paul Calderonef05fbbe2008-03-06 21:52:35 -0500791Returns \code{None} if they match, raises \exception{Error} otherwise.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500792\end{methoddesc}
793
794\begin{methoddesc}[Context]{get_app_data}{}
795Retrieve application data as set by \method{set_app_data}.
796\end{methoddesc}
797
798\begin{methoddesc}[Context]{get_cert_store}{}
799Retrieve the certificate store (a X509Store object) that the context uses.
800This can be used to add "trusted" certificates without using the.
801\method{load_verify_locations()} method.
802\end{methoddesc}
803
804\begin{methoddesc}[Context]{get_timeout}{}
805Retrieve session timeout, as set by \method{set_timeout}. The default is 300
806seconds.
807\end{methoddesc}
808
809\begin{methoddesc}[Context]{get_verify_depth}{}
810Retrieve the Context object's verify depth, as set by
811\method{set_verify_depth}.
812\end{methoddesc}
813
814\begin{methoddesc}[Context]{get_verify_mode}{}
Jean-Paul Calderoneae4238d2008-12-28 21:13:50 -0500815Retrieve the Context object's verify mode, as set by \method{set_verify}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500816\end{methoddesc}
817
818\begin{methoddesc}[Context]{load_client_ca}{pemfile}
819Read a file with PEM-formatted certificates that will be sent to the client
820when requesting a client certificate.
821\end{methoddesc}
822
Jean-Paul Calderone5601c242008-09-07 21:06:52 -0400823\begin{methoddesc}[Context]{load_verify_locations}{pemfile, capath}
824Specify where CA certificates for verification purposes are located. These
825are trusted certificates. Note that the certificates have to be in PEM
826format. If capath is passed, it must be a directory prepared using the
827\code{c_rehash} tool included with OpenSSL. Either, but not both, of
828\var{pemfile} or \var{capath} may be \code{None}.
829\end{methoddesc}
830
831\begin{methoddesc}[Context]{set_default_verify_paths}{}
832Specify that the platform provided CA certificates are to be used for
Jean-Paul Calderone1d287e52009-03-07 09:09:07 -0500833verification purposes. This method may not work properly on OS X.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500834\end{methoddesc}
835
836\begin{methoddesc}[Context]{load_tmp_dh}{dhfile}
837Load parameters for Ephemeral Diffie-Hellman from \var{dhfile}.
838\end{methoddesc}
839
840\begin{methoddesc}[Context]{set_app_data}{data}
841Associate \var{data} with this Context object. \var{data} can be retrieved
842later using the \method{get_app_data} method.
843\end{methoddesc}
844
845\begin{methoddesc}[Context]{set_cipher_list}{ciphers}
846Set the list of ciphers to be used in this context. See the OpenSSL manual for
847more information (e.g. ciphers(1))
848\end{methoddesc}
849
850\begin{methoddesc}[Context]{set_info_callback}{callback}
851Set the information callback to \var{callback}. This function will be called
852from time to time during SSL handshakes.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500853\var{callback} should take three arguments: a Connection object and two
854integers. The first integer specifies where in the SSL handshake the function
855was called, and the other the return code from a (possibly failed) internal
856function call.
857\end{methoddesc}
858
859\begin{methoddesc}[Context]{set_options}{options}
860Add SSL options. Options you have set before are not cleared!
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500861This method should be used with the \constant{OP_*} constants.
862\end{methoddesc}
863
864\begin{methoddesc}[Context]{set_passwd_cb}{callback\optional{, userdata}}
865Set the passphrase callback to \var{callback}. This function will be called
Jean-Paul Calderone1eeb29e2008-10-19 11:50:53 -0400866when a private key with a passphrase is loaded. \var{callback} must accept
867three positional arguments. First, an integer giving the maximum length of
868the passphrase it may return. If the returned passphrase is longer than
869this, it will be truncated. Second, a boolean value which will be true if
870the user should be prompted for the passphrase twice and the callback should
871verify that the two values supplied are equal. Third, the value given as the
872\var{userdata} parameter to \method{set_passwd_cb}. If an error occurs,
873\var{callback} should return a false value (e.g. an empty string).
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500874\end{methoddesc}
875
876\begin{methoddesc}[Context]{set_session_id}{name}
877Set the context \var{name} within which a session can be reused for this
878Context object. This is needed when doing session resumption, because there is
879no way for a stored session to know which Context object it is associated with.
880\var{name} may be any binary data.
881\end{methoddesc}
882
883\begin{methoddesc}[Context]{set_timeout}{timeout}
884Set the timeout for newly created sessions for this Context object to
885\var{timeout}. \var{timeout} must be given in (whole) seconds. The default
886value is 300 seconds. See the OpenSSL manual for more information (e.g.
887SSL_CTX_set_timeout(3)).
888\end{methoddesc}
889
890\begin{methoddesc}[Context]{set_verify}{mode, callback}
891Set the verification flags for this Context object to \var{mode} and specify
892that \var{callback} should be used for verification callbacks. \var{mode}
893should be one of \constant{VERIFY_NONE} and \constant{VERIFY_PEER}. If
894\constant{VERIFY_PEER} is used, \var{mode} can be OR:ed with
895\constant{VERIFY_FAIL_IF_NO_PEER_CERT} and \constant{VERIFY_CLIENT_ONCE} to
896further control the behaviour.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500897\var{callback} should take five arguments: A Connection object, an X509 object,
898and three integer variables, which are in turn potential error number, error
899depth and return code. \var{callback} should return true if verification passes
900and false otherwise.
901\end{methoddesc}
902
903\begin{methoddesc}[Context]{set_verify_depth}{depth}
904Set the maximum depth for the certificate chain verification that shall be
905allowed for this Context object.
906\end{methoddesc}
907
908\begin{methoddesc}[Context]{use_certificate}{cert}
909Use the certificate \var{cert} which has to be a X509 object.
910\end{methoddesc}
911
Jean-Paul Calderone87b40602008-02-19 21:13:25 -0500912\begin{methoddesc}[Context]{add_extra_chain_cert}{cert}
913Adds the certificate \var{cert}, which has to be a X509 object, to the
914certificate chain presented together with the certificate.
915\end{methoddesc}
916
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500917\begin{methoddesc}[Context]{use_certificate_chain_file}{file}
918Load a certificate chain from \var{file} which must be PEM encoded.
919\end{methoddesc}
920
921\begin{methoddesc}[Context]{use_privatekey}{pkey}
922Use the private key \var{pkey} which has to be a PKey object.
923\end{methoddesc}
924
925\begin{methoddesc}[Context]{use_certificate_file}{file\optional{, format}}
926Load the first certificate found in \var{file}. The certificate must be in the
927format specified by \var{format}, which is either \constant{FILETYPE_PEM} or
928\constant{FILETYPE_ASN1}. The default is \constant{FILETYPE_PEM}.
929\end{methoddesc}
930
931\begin{methoddesc}[Context]{use_privatekey_file}{file\optional{, format}}
932Load the first private key found in \var{file}. The private key must be in the
933format specified by \var{format}, which is either \constant{FILETYPE_PEM} or
934\constant{FILETYPE_ASN1}. The default is \constant{FILETYPE_PEM}.
935\end{methoddesc}
936
937
938\subsubsection{Connection objects \label{openssl-connection}}
939
940Connection objects have the following methods:
941
942\begin{methoddesc}[Connection]{accept}{}
943Call the \method{accept} method of the underlying socket and set up SSL on the
944returned socket, using the Context object supplied to this Connection object at
945creation. Returns a pair \code{(\var{conn}, \var{address})}. where \var{conn}
946is the new Connection object created, and \var{address} is as returned by the
947socket's \method{accept}.
948\end{methoddesc}
949
950\begin{methoddesc}[Connection]{bind}{address}
951Call the \method{bind} method of the underlying socket.
952\end{methoddesc}
953
954\begin{methoddesc}[Connection]{close}{}
955Call the \method{close} method of the underlying socket. Note: If you want
956correct SSL closure, you need to call the \method{shutdown} method first.
957\end{methoddesc}
958
959\begin{methoddesc}[Connection]{connect}{address}
960Call the \method{connect} method of the underlying socket and set up SSL on the
961socket, using the Context object supplied to this Connection object at
962creation.
963\end{methoddesc}
964
965\begin{methoddesc}[Connection]{connect_ex}{address}
966Call the \method{connect_ex} method of the underlying socket and set up SSL on
967the socket, using the Context object supplied to this Connection object at
968creation. Note that if the \method{connect_ex} method of the socket doesn't
969return 0, SSL won't be initialized.
970\end{methoddesc}
971
972\begin{methoddesc}[Connection]{do_handshake}{}
973Perform an SSL handshake (usually called after \method{renegotiate} or one of
974\method{set_accept_state} or \method{set_accept_state}). This can raise the
975same exceptions as \method{send} and \method{recv}.
976\end{methoddesc}
977
978\begin{methoddesc}[Connection]{fileno}{}
979Retrieve the file descriptor number for the underlying socket.
980\end{methoddesc}
981
982\begin{methoddesc}[Connection]{listen}{backlog}
983Call the \method{listen} method of the underlying socket.
984\end{methoddesc}
985
986\begin{methoddesc}[Connection]{get_app_data}{}
987Retrieve application data as set by \method{set_app_data}.
988\end{methoddesc}
989
990\begin{methoddesc}[Connection]{get_cipher_list}{}
991Retrieve the list of ciphers used by the Connection object. WARNING: This API
992has changed. It used to take an optional parameter and just return a string,
993but not it returns the entire list in one go.
994\end{methoddesc}
995
996\begin{methoddesc}[Connection]{get_context}{}
997Retrieve the Context object associated with this Connection.
998\end{methoddesc}
999
1000\begin{methoddesc}[Connection]{get_peer_certificate}{}
1001Retrieve the other side's certificate (if any)
1002\end{methoddesc}
1003
1004\begin{methoddesc}[Connection]{getpeername}{}
1005Call the \method{getpeername} method of the underlying socket.
1006\end{methoddesc}
1007
1008\begin{methoddesc}[Connection]{getsockname}{}
1009Call the \method{getsockname} method of the underlying socket.
1010\end{methoddesc}
1011
1012\begin{methoddesc}[Connection]{getsockopt}{level, optname\optional{, buflen}}
1013Call the \method{getsockopt} method of the underlying socket.
1014\end{methoddesc}
1015
1016\begin{methoddesc}[Connection]{pending}{}
Jean-Paul Calderoneb6f57be2008-03-06 21:22:16 -05001017Retrieve the number of bytes that can be safely read from the SSL buffer
1018(\emph{not} the underlying transport buffer).
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001019\end{methoddesc}
1020
1021\begin{methoddesc}[Connection]{recv}{bufsize}
1022Receive data from the Connection. The return value is a string representing the
1023data received. The maximum amount of data to be received at once, is specified
1024by \var{bufsize}.
1025\end{methoddesc}
1026
Jean-Paul Calderoneb6b17122009-05-01 16:36:11 -04001027\begin{methoddesc}[Connection]{bio_write}{bytes}
1028If the Connection was created with a memory BIO, this method can be used to add
1029bytes to the read end of that memory BIO. The Connection can then read the
1030bytes (for example, in response to a call to \method{recv}).
1031\end{methoddesc}
1032
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001033\begin{methoddesc}[Connection]{renegotiate}{}
1034Renegotiate the SSL session. Call this if you wish to change cipher suites or
1035anything like that.
1036\end{methoddesc}
1037
1038\begin{methoddesc}[Connection]{send}{string}
1039Send the \var{string} data to the Connection.
1040\end{methoddesc}
1041
Jean-Paul Calderoneb6b17122009-05-01 16:36:11 -04001042\begin{methoddesc}[Connection]{bio_read}{bufsize}
1043If the Connection was created with a memory BIO, this method can be used to
1044read bytes from the write end of that memory BIO. Many Connection methods will
1045add bytes which must be read in this manner or the buffer will eventually fill
1046up and the Connection will be able to take no further actions.
1047\end{methoddesc}
1048
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001049\begin{methoddesc}[Connection]{sendall}{string}
1050Send all of the \var{string} data to the Connection. This calls \method{send}
1051repeatedly until all data is sent. If an error occurs, it's impossible to tell
1052how much data has been sent.
1053\end{methoddesc}
1054
1055\begin{methoddesc}[Connection]{set_accept_state}{}
1056Set the connection to work in server mode. The handshake will be handled
1057automatically by read/write.
1058\end{methoddesc}
1059
1060\begin{methoddesc}[Connection]{set_app_data}{data}
1061Associate \var{data} with this Connection object. \var{data} can be retrieved
1062later using the \method{get_app_data} method.
1063\end{methoddesc}
1064
1065\begin{methoddesc}[Connection]{set_connect_state}{}
1066Set the connection to work in client mode. The handshake will be handled
1067automatically by read/write.
1068\end{methoddesc}
1069
1070\begin{methoddesc}[Connection]{setblocking}{flag}
1071Call the \method{setblocking} method of the underlying socket.
1072\end{methoddesc}
1073
1074\begin{methoddesc}[Connection]{setsockopt}{level, optname, value}
1075Call the \method{setsockopt} method of the underlying socket.
1076\end{methoddesc}
1077
1078\begin{methoddesc}[Connection]{shutdown}{}
1079Send the shutdown message to the Connection. Returns true if the shutdown
1080message exchange is completed and false otherwise (in which case you call
1081\method{recv()} or \method{send()} when the connection becomes
1082readable/writeable.
1083\end{methoddesc}
1084
Jean-Paul Calderone72b8f0f2008-02-21 23:57:40 -05001085\begin{methoddesc}[Connection]{get_shutdown}{}
1086Get the shutdown state of the Connection. Returns a bitvector of either or
1087both of \var{SENT_SHUTDOWN} and \var{RECEIVED_SHUTDOWN}.
1088\end{methoddesc}
1089
1090\begin{methoddesc}[Connection]{set_shutdown}{state}
1091Set the shutdown state of the Connection. \var{state} is a bitvector of
1092either or both of \var{SENT_SHUTDOWN} and \var{RECEIVED_SHUTDOWN}.
1093\end{methoddesc}
1094
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001095\begin{methoddesc}[Connection]{sock_shutdown}{how}
1096Call the \method{shutdown} method of the underlying socket.
1097\end{methoddesc}
1098
Jean-Paul Calderoneb6b17122009-05-01 16:36:11 -04001099\begin{methoddesc}[Connection]{bio_shutdown}{}
1100If the Connection was created with a memory BIO, this method can be used to
1101indicate that ``end of file'' has been reached on the read end of that memory
1102BIO.
1103\end{methoddesc}
1104
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001105\begin{methoddesc}[Connection]{state_string}{}
1106Retrieve a verbose string detailing the state of the Connection.
1107\end{methoddesc}
1108
Jean-Paul Calderonefd236f32009-05-03 19:45:07 -04001109\begin{methoddesc}[Connection]{client_random}{}
1110Retrieve the random value used with the client hello message.
1111\end{methoddesc}
1112
1113\begin{methoddesc}[Connection]{server_random}{}
1114Retrieve the random value used with the server hello message.
1115\end{methoddesc}
1116
1117\begin{methoddesc}[Connection]{master_key}{}
1118Retrieve the value of the master key for this session.
1119\end{methoddesc}
1120
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001121\begin{methoddesc}[Connection]{want_read}{}
1122Checks if more data has to be read from the transport layer to complete an
1123operation.
1124\end{methoddesc}
1125
1126\begin{methoddesc}[Connection]{want_write}{}
1127Checks if there is data to write to the transport layer to complete an
1128operation.
1129\end{methoddesc}
1130
1131
1132
1133\section{Internals \label{internals}}
1134
1135We ran into three main problems developing this: Exceptions, callbacks and
1136accessing socket methods. This is what this chapter is about.
1137
1138\subsection{Exceptions \label{exceptions}}
1139
1140We realized early that most of the exceptions would be raised by the I/O
1141functions of OpenSSL, so it felt natural to mimic OpenSSL's error code system,
1142translating them into Python exceptions. This naturally gives us the exceptions
1143\exception{SSL.ZeroReturnError}, \exception{SSL.WantReadError},
1144\exception{SSL.WantWriteError}, \exception{SSL.WantX509LookupError} and
1145\exception{SSL.SysCallError}.
1146
1147For more information about this, see section \ref{openssl-ssl}.
1148
1149
1150\subsection{Callbacks \label{callbacks}}
1151
1152There are a number of problems with callbacks. First of all, OpenSSL is written
1153as a C library, it's not meant to have Python callbacks, so a way around that
1154is needed. Another problem is thread support. A lot of the OpenSSL I/O
1155functions can block if the socket is in blocking mode, and then you want other
1156Python threads to be able to do other things. The real trouble is if you've
Jean-Paul Calderoneb7d6db22008-09-21 18:57:56 -04001157released the global CPython interpreter lock to do a potentially blocking
1158operation, and the operation calls a callback. Then we must take the GIL back,
1159since calling Python APIs without holding it is not allowed.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001160
1161There are two solutions to the first problem, both of which are necessary. The
1162first solution to use is if the C callback allows ''userdata'' to be passed to
1163it (an arbitrary pointer normally). This is great! We can set our Python
1164function object as the real userdata and emulate userdata for the Python
1165function in another way. The other solution can be used if an object with an
1166''app_data'' system always is passed to the callback. For example, the SSL
1167object in OpenSSL has app_data functions and in e.g. the verification
1168callbacks, you can retrieve the related SSL object. What we do is to set our
1169wrapper \class{Connection} object as app_data for the SSL object, and we can
1170easily find the Python callback.
1171
Jean-Paul Calderoneb7d6db22008-09-21 18:57:56 -04001172The other problem is solved using thread local variables. Whenever the GIL is
1173released before calling into an OpenSSL API, the PyThreadState pointer returned
1174by \cfunction{PyEval_SaveState} is stored in a global thread local variable
1175(using Python's own TLS API, \cfunction{PyThread_set_key_value}). When it is
1176necessary to re-acquire the GIL, either after the OpenSSL API returns or in a C
1177callback invoked by that OpenSSL API, the value of the thread local variable is
1178retrieved (\cfunction{PyThread_get_key_value}) and used to re-acquire the GIL.
1179This allows Python threads to execute while OpenSSL APIs are running and allows
1180use of any particular pyOpenSSL object from any Python thread, since there is
1181no per-thread state associated with any of these objects and since OpenSSL is
1182threadsafe (as long as properly initialized, as pyOpenSSL initializes it).
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001183
1184
1185\subsection{Acessing Socket Methods \label{socket-methods}}
1186
1187We quickly saw the benefit of wrapping socket methods in the
1188\class{SSL.Connection} class, for an easy transition into using SSL. The
1189problem here is that the \module{socket} module lacks a C API, and all the
1190methods are declared static. One approach would be to have \module{OpenSSL} as
1191a submodule to the \module{socket} module, placing all the code in
1192\file{socketmodule.c}, but this is obviously not a good solution, since you
1193might not want to import tonnes of extra stuff you're not going to use when
1194importing the \module{socket} module. The other approach is to somehow get a
1195pointer to the method to be called, either the C function, or a callable Python
1196object. This is not really a good solution either, since there's a lot of
1197lookups involved.
1198
1199The way it works is that you have to supply a ``\class{socket}-like'' transport
1200object to the \class{SSL.Connection}. The only requirement of this object is
1201that it has a \method{fileno()} method that returns a file descriptor that's
1202valid at the C level (i.e. you can use the system calls read and write). If you
1203want to use the \method{connect()} or \method{accept()} methods of the
1204\class{SSL.Connection} object, the transport object has to supply such
1205methods too. Apart from them, any method lookups in the \class{SSL.Connection}
1206object that fail are passed on to the underlying transport object.
1207
1208Future changes might be to allow Python-level transport objects, that instead
1209of having \method{fileno()} methods, have \method{read()} and \method{write()}
1210methods, so more advanced features of Python can be used. This would probably
1211entail some sort of OpenSSL ``BIOs'', but converting Python strings back and
1212forth is expensive, so this shouldn't be used unless necessary. Other nice
1213things would be to be able to pass in different transport objects for reading
1214and writing, but then the \method{fileno()} method of \class{SSL.Connection}
1215becomes virtually useless. Also, should the method resolution be used on the
1216read-transport or the write-transport?
1217
1218
1219\end{document}