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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
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400191\begin{classdesc}{X509Extension}{typename, critical, value}
192A class representing an X.509 v3 certificate extensions.
193\end{classdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500194
195\begin{datadesc}{NetscapeSPKIType}
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400196See \class{NetscapeSPKI}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500197\end{datadesc}
198
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400199\begin{classdesc}{NetscapeSPKI}{\optional{enc}}
200A class representing Netscape SPKI objects.
201
202If the \var{enc} argument is present, it should be a base64-encoded string
203representing a NetscapeSPKI object, as returned by the \method{b64_encode}
204method.
205\end{classdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500206
207\begin{datadesc}{FILETYPE_PEM}
208\dataline{FILETYPE_ASN1}
209File type constants.
210\end{datadesc}
211
212\begin{datadesc}{TYPE_RSA}
213\dataline{TYPE_DSA}
214Key type constants.
215\end{datadesc}
216
217\begin{excdesc}{Error}
218Generic exception used in the \module{crypto} module.
219\end{excdesc}
220
221\begin{funcdesc}{dump_certificate}{type, cert}
222Dump the certificate \var{cert} into a buffer string encoded with the type
223\var{type}.
224\end{funcdesc}
225
226\begin{funcdesc}{dump_certificate_request}{type, req}
227Dump the certificate request \var{req} into a buffer string encoded with the
228type \var{type}.
229\end{funcdesc}
230
231\begin{funcdesc}{dump_privatekey}{type, pkey\optional{, cipher, passphrase}}
232Dump the private key \var{pkey} into a buffer string encoded with the type
233\var{type}, optionally (if \var{type} is \constant{FILETYPE_PEM}) encrypting it
234using \var{cipher} and \var{passphrase}.
235
236\var{passphrase} must be either a string or a callback for providing the
237pass phrase.
238\end{funcdesc}
239
240\begin{funcdesc}{load_certificate}{type, buffer}
241Load a certificate (X509) from the string \var{buffer} encoded with the
242type \var{type}.
243\end{funcdesc}
244
245\begin{funcdesc}{load_certificate_request}{type, buffer}
246Load a certificate request (X509Req) from the string \var{buffer} encoded with
247the type \var{type}.
248\end{funcdesc}
249
250\begin{funcdesc}{load_privatekey}{type, buffer\optional{, passphrase}}
251Load a private key (PKey) from the string \var{buffer} encoded with
252the type \var{type} (must be one of \constant{FILETYPE_PEM} and
253\constant{FILETYPE_ASN1}).
254
255\var{passphrase} must be either a string or a callback for providing the
256pass phrase.
257\end{funcdesc}
258
259\begin{funcdesc}{load_pkcs7_data}{type, buffer}
260Load pkcs7 data from the string \var{buffer} encoded with the type \var{type}.
261\end{funcdesc}
262
263\begin{funcdesc}{load_pkcs12}{buffer\optional{, passphrase}}
264Load pkcs12 data from the string \var{buffer}. If the pkcs12 structure is
265encrypted, a \var{passphrase} must be included.
266\end{funcdesc}
267
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500268\subsubsection{X509 objects \label{openssl-x509}}
269
270X509 objects have the following methods:
271
272\begin{methoddesc}[X509]{get_issuer}{}
Jean-Paul Calderone2aa2b332008-03-06 21:43:14 -0500273Return an X509Name object representing the issuer of the certificate.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500274\end{methoddesc}
275
276\begin{methoddesc}[X509]{get_pubkey}{}
277Return a PKey object representing the public key of the certificate.
278\end{methoddesc}
279
280\begin{methoddesc}[X509]{get_serial_number}{}
281Return the certificate serial number.
282\end{methoddesc}
283
284\begin{methoddesc}[X509]{get_subject}{}
Jean-Paul Calderone2aa2b332008-03-06 21:43:14 -0500285Return an X509Name object representing the subject of the certificate.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500286\end{methoddesc}
287
288\begin{methoddesc}[X509]{get_version}{}
289Return the certificate version.
290\end{methoddesc}
291
Jean-Paul Calderone525ef802008-03-09 20:39:42 -0400292\begin{methoddesc}[X509]{get_notBefore}{}
293Return a string giving the time before which the certificate is not valid. The
294string is formatted as an ASN1 GENERALIZEDTIME:
295\begin{verbatim}
296 YYYYMMDDhhmmssZ
297 YYYYMMDDhhmmss+hhmm
298 YYYYMMDDhhmmss-hhmm
299\end{verbatim}
Jean-Paul Calderonee0615b52008-03-09 21:44:46 -0400300If no value exists for this field, \code{None} is returned.
Jean-Paul Calderone525ef802008-03-09 20:39:42 -0400301\end{methoddesc}
302
303\begin{methoddesc}[X509]{get_notAfter}{}
304Return a string giving the time after which the certificate is not valid. The
305string is formatted as an ASN1 GENERALIZEDTIME:
306\begin{verbatim}
307 YYYYMMDDhhmmssZ
308 YYYYMMDDhhmmss+hhmm
309 YYYYMMDDhhmmss-hhmm
310\end{verbatim}
Jean-Paul Calderonee0615b52008-03-09 21:44:46 -0400311If no value exists for this field, \code{None} is returned.
Jean-Paul Calderone525ef802008-03-09 20:39:42 -0400312\end{methoddesc}
313
314\begin{methoddesc}[X509]{set_notBefore}{when}
315Change the time before which the certificate is not valid. \var{when} is a
316string formatted as an ASN1 GENERALIZEDTIME:
317\begin{verbatim}
318 YYYYMMDDhhmmssZ
319 YYYYMMDDhhmmss+hhmm
320 YYYYMMDDhhmmss-hhmm
321\end{verbatim}
322\end{methoddesc}
323
324\begin{methoddesc}[X509]{set_notAfter}{when}
325Change the time after which the certificate is not valid. \var{when} is a
326string formatted as an ASN1 GENERALIZEDTIME:
327\begin{verbatim}
328 YYYYMMDDhhmmssZ
329 YYYYMMDDhhmmss+hhmm
330 YYYYMMDDhhmmss-hhmm
331\end{verbatim}
332\end{methoddesc}
333
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500334\begin{methoddesc}[X509]{gmtime_adj_notBefore}{time}
335Adjust the timestamp (in GMT) when the certificate starts being valid.
336\end{methoddesc}
337
338\begin{methoddesc}[X509]{gmtime_adj_notAfter}{time}
339Adjust the timestamp (in GMT) when the certificate stops being valid.
340\end{methoddesc}
341
342\begin{methoddesc}[X509]{has_expired}{}
343Checks the certificate's time stamp against current time. Returns true if the
344certificate has expired and false otherwise.
345\end{methoddesc}
346
347\begin{methoddesc}[X509]{set_issuer}{issuer}
348Set the issuer of the certificate to \var{issuer}.
349\end{methoddesc}
350
351\begin{methoddesc}[X509]{set_pubkey}{pkey}
352Set the public key of the certificate to \var{pkey}.
353\end{methoddesc}
354
355\begin{methoddesc}[X509]{set_serial_number}{serialno}
356Set the serial number of the certificate to \var{serialno}.
357\end{methoddesc}
358
359\begin{methoddesc}[X509]{set_subject}{subject}
360Set the subject of the certificate to \var{subject}.
361\end{methoddesc}
362
363\begin{methoddesc}[X509]{set_version}{version}
364Set the certificate version to \var{version}.
365\end{methoddesc}
366
367\begin{methoddesc}[X509]{sign}{pkey, digest}
368Sign the certificate, using the key \var{pkey} and the message digest algorithm
369identified by the string \var{digest}.
370\end{methoddesc}
371
372\begin{methoddesc}[X509]{subject_name_hash}{}
373Return the hash of the certificate subject.
374\end{methoddesc}
375
376\begin{methoddesc}[X509]{digest}{digest_name}
377Return a digest of the certificate, using the \var{digest_name} method.
Jean-Paul Calderoneb6f0d602008-12-28 21:20:01 -0500378\var{digest_name} must be a string describing a digest algorithm supported
379by OpenSSL (by EVP_get_digestbyname, specifically). For example,
380\constant{"md5"} or \constant{"sha1"}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500381\end{methoddesc}
382
383\begin{methoddesc}[X509]{add_extensions}{extensions}
384Add the extensions in the sequence \var{extensions} to the certificate.
385\end{methoddesc}
386
387\subsubsection{X509Name objects \label{openssl-x509name}}
388
Jean-Paul Calderone2dd8ff52008-03-24 17:43:58 -0400389X509Name objects have the following methods:
390
391\begin{methoddesc}[X509Name]{hash}{}
392Return an integer giving the first four bytes of the MD5 digest of the DER
393representation of the name.
394\end{methoddesc}
395
Jean-Paul Calderonea6edbf82008-03-25 15:19:11 -0400396\begin{methoddesc}[X509Name]{der}{}
397Return a string giving the DER representation of the name.
398\end{methoddesc}
399
Jean-Paul Calderonec54cc182008-03-26 21:11:07 -0400400\begin{methoddesc}[X509Name]{get_components}{}
401Return a list of two-tuples of strings giving the components of the name.
402\end{methoddesc}
403
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500404X509Name objects have the following members:
405
406\begin{memberdesc}[X509Name]{countryName}
407The country of the entity. \code{C} may be used as an alias for
408\code{countryName}.
409\end{memberdesc}
410
411\begin{memberdesc}[X509Name]{stateOrProvinceName}
412The state or province of the entity. \code{ST} may be used as an alias for
413\code{stateOrProvinceName}·
414\end{memberdesc}
415
416\begin{memberdesc}[X509Name]{localityName}
417The locality of the entity. \code{L} may be used as an alias for
418\code{localityName}.
419\end{memberdesc}
420
421\begin{memberdesc}[X509Name]{organizationName}
422The organization name of the entity. \code{O} may be used as an alias for
423\code{organizationName}.
424\end{memberdesc}
425
426\begin{memberdesc}[X509Name]{organizationalUnitName}
427The organizational unit of the entity. \code{OU} may be used as an alias for
428\code{organizationalUnitName}.
429\end{memberdesc}
430
431\begin{memberdesc}[X509Name]{commonName}
432The common name of the entity. \code{CN} may be used as an alias for
433\code{commonName}.
434\end{memberdesc}
435
436\begin{memberdesc}[X509Name]{emailAddress}
437The e-mail address of the entity.
438\end{memberdesc}
439
440\subsubsection{X509Req objects \label{openssl-x509req}}
441
442X509Req objects have the following methods:
443
444\begin{methoddesc}[X509Req]{get_pubkey}{}
445Return a PKey object representing the public key of the certificate request.
446\end{methoddesc}
447
448\begin{methoddesc}[X509Req]{get_subject}{}
Jean-Paul Calderone2aa2b332008-03-06 21:43:14 -0500449Return an X509Name object representing the subject of the certificate.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500450\end{methoddesc}
451
452\begin{methoddesc}[X509Req]{set_pubkey}{pkey}
453Set the public key of the certificate request to \var{pkey}.
454\end{methoddesc}
455
456\begin{methoddesc}[X509Req]{sign}{pkey, digest}
457Sign the certificate request, using the key \var{pkey} and the message digest
458algorithm identified by the string \var{digest}.
459\end{methoddesc}
460
461\begin{methoddesc}[X509Req]{verify}{pkey}
462Verify a certificate request using the public key \var{pkey}.
463\end{methoddesc}
464
Jean-Paul Calderone8dd19b82008-12-28 20:41:16 -0500465\begin{methoddesc}[X509Req]{set_version}{version}
466Set the version (RFC 2459, 4.1.2.1) of the certificate request to
467\var{version}.
468\end{methoddesc}
469
470\begin{methoddesc}[X509Req]{get_version}{}
471Get the version (RFC 2459, 4.1.2.1) of the certificate request.
472\end{methoddesc}
473
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500474\subsubsection{X509Store objects \label{openssl-x509store}}
475
476The X509Store object has currently just one method:
477
478\begin{methoddesc}[X509Store]{add_cert}{cert}
479Add the certificate \var{cert} to the certificate store.
480\end{methoddesc}
481
482\subsubsection{PKey objects \label{openssl-pkey}}
483
484The PKey object has the following methods:
485
486\begin{methoddesc}[PKey]{bits}{}
487Return the number of bits of the key.
488\end{methoddesc}
489
490\begin{methoddesc}[PKey]{generate_key}{type, bits}
491Generate a public/private key pair of the type \var{type} (one of
492\constant{TYPE_RSA} and \constant{TYPE_DSA}) with the size \var{bits}.
493\end{methoddesc}
494
495\begin{methoddesc}[PKey]{type}{}
496Return the type of the key.
497\end{methoddesc}
498
499\subsubsection{PKCS7 objects \label{openssl-pkcs7}}
500
501PKCS7 objects have the following methods:
502
503\begin{methoddesc}[PKCS7]{type_is_signed}{}
504FIXME
505\end{methoddesc}
506
507\begin{methoddesc}[PKCS7]{type_is_enveloped}{}
508FIXME
509\end{methoddesc}
510
511\begin{methoddesc}[PKCS7]{type_is_signedAndEnveloped}{}
512FIXME
513\end{methoddesc}
514
515\begin{methoddesc}[PKCS7]{type_is_data}{}
516FIXME
517\end{methoddesc}
518
519\begin{methoddesc}[PKCS7]{get_type_name}{}
520Get the type name of the PKCS7.
521\end{methoddesc}
522
523\subsubsection{PKCS12 objects \label{openssl-pkcs12}}
524
525PKCS12 objects have the following methods:
526
Rick Deane182f482009-07-17 14:49:48 -0500527\begin{methoddesc}[PKCS12]{export}{\optional{passphrase=None}\optional{, friendly_name=None}\optional{, iter=2000}\optional{, maciter=0}}
528Returns a PKCS12 object as a string.
529
530The optional \var{passphrase} must be a string not a callback.
531
532See also the man page for the C function \function{PKCS12_create}.
533\end{methoddesc}
534
535\begin{methoddesc}[PKCS12]{get_ca_certificates}{}
536Return CA certificates within the PKCS12 object as a tuple. Returns
537\constant{None} if no CA certificates are present.
538\end{methoddesc}
539
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500540\begin{methoddesc}[PKCS12]{get_certificate}{}
541Return certificate portion of the PKCS12 structure.
542\end{methoddesc}
543
544\begin{methoddesc}[PKCS12]{get_privatekey}{}
545Return private key portion of the PKCS12 structure
546\end{methoddesc}
547
Rick Deane182f482009-07-17 14:49:48 -0500548\begin{methoddesc}[PKCS12]{set_ca_certificates}{cacerts}
549Replace or set the CA certificates within the PKCS12 object with the sequence \var{cacerts}.
550
551Set \var{cacerts} to \constant{None} to remove all CA certificates.
552\end{methoddesc}
553
554\begin{methoddesc}[PKCS12]{set_certificate}{cert}
555Replace or set the certificate portion of the PKCS12 structure.
556\end{methoddesc}
557
558\begin{methoddesc}[PKCS12]{set_privatekey}{pkey}
559Replace or set private key portion of the PKCS12 structure
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500560\end{methoddesc}
561
562\subsubsection{X509Extension objects \label{openssl-509ext}}
563
Jean-Paul Calderonef8c5fab2008-12-31 15:53:48 -0500564X509Extension objects have several methods:
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500565
566\begin{methoddesc}[X509Extension]{get_critical}{}
567Return the critical field of the extension object.
568\end{methoddesc}
569
Jean-Paul Calderonef8c5fab2008-12-31 15:53:48 -0500570\begin{methoddesc}[X509Extension]{get_short_name}{}
571Return the short type name of the extension object.
572\end{methoddesc}
573
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500574\subsubsection{NetscapeSPKI objects \label{openssl-netscape-spki}}
575
576NetscapeSPKI objects have the following methods:
577
578\begin{methoddesc}[NetscapeSPKI]{b64_encode}{}
579Return a base64-encoded string representation of the object.
580\end{methoddesc}
581
582\begin{methoddesc}[NetscapeSPKI]{get_pubkey}{}
583Return the public key of object.
584\end{methoddesc}
585
586\begin{methoddesc}[NetscapeSPKI]{set_pubkey}{key}
587Set the public key of the object to \var{key}.
588\end{methoddesc}
589
590\begin{methoddesc}[NetscapeSPKI]{sign}{key, digest_name}
Jean-Paul Calderoneb6f0d602008-12-28 21:20:01 -0500591Sign the NetscapeSPKI object using the given \var{key} and
592\var{digest_name}. \var{digest_name} must be a string describing a digest
593algorithm supported by OpenSSL (by EVP_get_digestbyname, specifically). For
594example, \constant{"md5"} or \constant{"sha1"}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500595\end{methoddesc}
596
597\begin{methoddesc}[NetscapeSPKI]{verify}{key}
598Verify the NetscapeSPKI object using the given \var{key}.
599\end{methoddesc}
600
601
602% % % rand module
603
604\subsection{\module{rand} --- An interface to the OpenSSL pseudo random number generator \label{openssl-rand}}
605
606\declaremodule{extension}{rand}
607\modulesynopsis{An interface to the OpenSSL pseudo random number generator}
608
609This module handles the OpenSSL pseudo random number generator (PRNG) and
610declares the following:
611
612\begin{funcdesc}{add}{string, entropy}
613Mix bytes from \var{string} into the PRNG state. The \var{entropy} argument is
614(the lower bound of) an estimate of how much randomness is contained in
615\var{string}, measured in bytes. For more information, see e.g. \rfc{1750}.
616\end{funcdesc}
617
Rick Dean4fd5a4e2009-07-08 12:06:10 -0500618\begin{funcdesc}{bytes}{num_bytes}
Jean-Paul Calderonea45e2b92009-07-08 13:29:58 -0400619Get some random bytes from the PRNG as a string.
620
621This is a wrapper for the C function \function{RAND_bytes}.
Rick Dean4fd5a4e2009-07-08 12:06:10 -0500622\end{funcdesc}
623
Rick Dean433dc642009-07-07 13:11:55 -0500624\begin{funcdesc}{cleanup}{}
Jean-Paul Calderone427c0b32009-07-07 15:43:27 -0400625Erase the memory used by the PRNG.
626
627This is a wrapper for the C function \function{RAND_cleanup}.
Rick Dean433dc642009-07-07 13:11:55 -0500628\end{funcdesc}
629
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500630\begin{funcdesc}{egd}{path\optional{, bytes}}
631Query the Entropy Gathering Daemon\footnote{See
632\url{http://www.lothar.com/tech/crypto/}} on socket \var{path} for \var{bytes}
633bytes of random data and and uses \function{add} to seed the PRNG. The default
634value of \var{bytes} is 255.
635\end{funcdesc}
636
637\begin{funcdesc}{load_file}{path\optional{, bytes}}
638Read \var{bytes} bytes (or all of it, if \var{bytes} is negative) of data from
639the file \var{path} to seed the PRNG. The default value of \var{bytes} is -1.
640\end{funcdesc}
641
642\begin{funcdesc}{screen}{}
643Add the current contents of the screen to the PRNG state.
644Availability: Windows.
645\end{funcdesc}
646
647\begin{funcdesc}{seed}{string}
648This is equivalent to calling \function{add} with \var{entropy} as the length
649of the string.
650\end{funcdesc}
651
652\begin{funcdesc}{status}{}
653Returns true if the PRNG has been seeded with enough data, and false otherwise.
654\end{funcdesc}
655
656\begin{funcdesc}{write_file}{path}
657Write a number of random bytes (currently 1024) to the file \var{path}. This
658file can then be used with \function{load_file} to seed the PRNG again.
659\end{funcdesc}
660
Rick Deanfc69c812009-07-08 11:03:47 -0500661\begin{excdesc}{Error}
662If the current RAND method supports any errors, this is raised when needed.
663The default method does not raise this when the entropy pool is depleted.
664
665Whenever this exception is raised directly, it has a list of error messages
666from the OpenSSL error queue, where each item is a tuple \code{(\var{lib},
667\var{function}, \var{reason})}. Here \var{lib}, \var{function} and \var{reason}
668are all strings, describing where and what the problem is. See \manpage{err}{3}
669for more information.
670\end{excdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500671
672
673% % % SSL module
674
675\subsection{\module{SSL} --- An interface to the SSL-specific parts of OpenSSL \label{openssl-ssl}}
676
677\declaremodule{extension}{SSL}
678\modulesynopsis{An interface to the SSL-specific parts of OpenSSL}
679
680This module handles things specific to SSL. There are two objects defined:
681Context, Connection.
682
683\begin{datadesc}{SSLv2_METHOD}
684\dataline{SSLv3_METHOD}
685\dataline{SSLv23_METHOD}
686\dataline{TLSv1_METHOD}
687These constants represent the different SSL methods to use when creating a
688context object.
689\end{datadesc}
690
691\begin{datadesc}{VERIFY_NONE}
692\dataline{VERIFY_PEER}
693\dataline{VERIFY_FAIL_IF_NO_PEER_CERT}
694These constants represent the verification mode used by the Context
695object's \method{set_verify} method.
696\end{datadesc}
697
698\begin{datadesc}{FILETYPE_PEM}
699\dataline{FILETYPE_ASN1}
700File type constants used with the \method{use_certificate_file} and
701\method{use_privatekey_file} methods of Context objects.
702\end{datadesc}
703
704\begin{datadesc}{OP_SINGLE_DH_USE}
705\dataline{OP_EPHEMERAL_RSA}
706\dataline{OP_NO_SSLv2}
707\dataline{OP_NO_SSLv3}
708\dataline{OP_NO_TLSv1}
709Constants used with \method{set_options} of Context objects.
710\constant{OP_SINGLE_DH_USE} means to always create a new key when using ephemeral
711Diffie-Hellman. \constant{OP_EPHEMERAL_RSA} means to always use ephemeral RSA keys
712when doing RSA operations. \constant{OP_NO_SSLv2}, \constant{OP_NO_SSLv3} and
713\constant{OP_NO_TLSv1} means to disable those specific protocols. This is
714interesting if you're using e.g. \constant{SSLv23_METHOD} to get an SSLv2-compatible
715handshake, but don't want to use SSLv2.
716\end{datadesc}
717
718\begin{datadesc}{ContextType}
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400719See \class{Context}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500720\end{datadesc}
721
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400722\begin{classdesc}{Context}{method}
723A class representing SSL contexts. Contexts define the parameters of one or
724more SSL connections.
725
726\var{method} should be \constant{SSLv2_METHOD}, \constant{SSLv3_METHOD},
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500727\constant{SSLv23_METHOD} or \constant{TLSv1_METHOD}.
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400728\end{classdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500729
730\begin{datadesc}{ConnectionType}
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400731See \class{Connection}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500732\end{datadesc}
733
Jean-Paul Calderonefc4abd02009-07-04 16:15:36 -0400734\begin{classdesc}{Connection}{context, socket}
735A class representing SSL connections.
736
737\var{context} should be an instance of \class{Context} and \var{socket}
738should be a socket \footnote{Actually, all that is required is an object
739that \emph{behaves} like a socket, you could even use files, even though
740it'd be tricky to get the handshakes right!} object. \var{socket} may be
741\var{None}; in this case, the Connection is created with a memory BIO: see
742the \method{bio_read}, \method{bio_write}, and \method{bio_shutdown}
743methods.
744\end{classdesc}
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500745
746\begin{excdesc}{Error}
747This exception is used as a base class for the other SSL-related
748exceptions, but may also be raised directly.
749
750Whenever this exception is raised directly, it has a list of error messages
751from the OpenSSL error queue, where each item is a tuple \code{(\var{lib},
752\var{function}, \var{reason})}. Here \var{lib}, \var{function} and \var{reason}
753are all strings, describing where and what the problem is. See \manpage{err}{3}
754for more information.
755\end{excdesc}
756
757\begin{excdesc}{ZeroReturnError}
758This exception matches the error return code \code{SSL_ERROR_ZERO_RETURN}, and
759is raised when the SSL Connection has been closed. In SSL 3.0 and TLS 1.0, this
760only occurs if a closure alert has occurred in the protocol, i.e. the
761connection has been closed cleanly. Note that this does not necessarily
762mean that the transport layer (e.g. a socket) has been closed.
763
764It may seem a little strange that this is an exception, but it does match an
765\code{SSL_ERROR} code, and is very convenient.
766\end{excdesc}
767
768\begin{excdesc}{WantReadError}
769The operation did not complete; the same I/O method should be called again
770later, with the same arguments. Any I/O method can lead to this since new
771handshakes can occur at any time.
Rick Dean71fa0962009-07-09 23:56:39 -0500772
Jean-Paul Calderonecc787d52009-07-16 12:08:41 -0400773The wanted read is for \emph{dirty} data sent over the network, not the
774\emph{clean} data inside the tunnel. For a socket based SSL connection,
775\emph{read} means data coming at us over the network. Until that read
776succeeds, the attempted \method{OpenSSL.SSL.Connection.recv},
Rick Dean71fa0962009-07-09 23:56:39 -0500777\method{OpenSSL.SSL.Connection.send}, or
Jean-Paul Calderonecc787d52009-07-16 12:08:41 -0400778\method{OpenSSL.SSL.Connection.do_handshake} is prevented or incomplete. You
779probably want to \method{select()} on the socket before trying again.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500780\end{excdesc}
781
782\begin{excdesc}{WantWriteError}
Jean-Paul Calderonecc787d52009-07-16 12:08:41 -0400783See \exception{WantReadError}. The socket send buffer may be too full to
Rick Dean71fa0962009-07-09 23:56:39 -0500784write more data.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500785\end{excdesc}
786
787\begin{excdesc}{WantX509LookupError}
788The operation did not complete because an application callback has asked to be
789called again. The I/O method should be called again later, with the same
790arguments. Note: This won't occur in this version, as there are no such
791callbacks in this version.
792\end{excdesc}
793
794\begin{excdesc}{SysCallError}
795The \exception{SysCallError} occurs when there's an I/O error and OpenSSL's
796error queue does not contain any information. This can mean two things: An
797error in the transport protocol, or an end of file that violates the protocol.
798The parameter to the exception is always a pair \code{(\var{errnum},
799\var{errstr})}.
800\end{excdesc}
801
802
803\subsubsection{Context objects \label{openssl-context}}
804
805Context objects have the following methods:
806
807\begin{methoddesc}[Context]{check_privatekey}{}
808Check if the private key (loaded with \method{use_privatekey\optional{_file}})
809matches the certificate (loaded with \method{use_certificate\optional{_file}}).
Jean-Paul Calderonef05fbbe2008-03-06 21:52:35 -0500810Returns \code{None} if they match, raises \exception{Error} otherwise.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500811\end{methoddesc}
812
813\begin{methoddesc}[Context]{get_app_data}{}
814Retrieve application data as set by \method{set_app_data}.
815\end{methoddesc}
816
817\begin{methoddesc}[Context]{get_cert_store}{}
818Retrieve the certificate store (a X509Store object) that the context uses.
819This can be used to add "trusted" certificates without using the.
820\method{load_verify_locations()} method.
821\end{methoddesc}
822
823\begin{methoddesc}[Context]{get_timeout}{}
824Retrieve session timeout, as set by \method{set_timeout}. The default is 300
825seconds.
826\end{methoddesc}
827
828\begin{methoddesc}[Context]{get_verify_depth}{}
829Retrieve the Context object's verify depth, as set by
830\method{set_verify_depth}.
831\end{methoddesc}
832
833\begin{methoddesc}[Context]{get_verify_mode}{}
Jean-Paul Calderoneae4238d2008-12-28 21:13:50 -0500834Retrieve the Context object's verify mode, as set by \method{set_verify}.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500835\end{methoddesc}
836
837\begin{methoddesc}[Context]{load_client_ca}{pemfile}
838Read a file with PEM-formatted certificates that will be sent to the client
839when requesting a client certificate.
840\end{methoddesc}
841
Jean-Paul Calderone5601c242008-09-07 21:06:52 -0400842\begin{methoddesc}[Context]{load_verify_locations}{pemfile, capath}
843Specify where CA certificates for verification purposes are located. These
844are trusted certificates. Note that the certificates have to be in PEM
845format. If capath is passed, it must be a directory prepared using the
846\code{c_rehash} tool included with OpenSSL. Either, but not both, of
847\var{pemfile} or \var{capath} may be \code{None}.
848\end{methoddesc}
849
850\begin{methoddesc}[Context]{set_default_verify_paths}{}
851Specify that the platform provided CA certificates are to be used for
Jean-Paul Calderone1d287e52009-03-07 09:09:07 -0500852verification purposes. This method may not work properly on OS X.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500853\end{methoddesc}
854
855\begin{methoddesc}[Context]{load_tmp_dh}{dhfile}
856Load parameters for Ephemeral Diffie-Hellman from \var{dhfile}.
857\end{methoddesc}
858
859\begin{methoddesc}[Context]{set_app_data}{data}
860Associate \var{data} with this Context object. \var{data} can be retrieved
861later using the \method{get_app_data} method.
862\end{methoddesc}
863
864\begin{methoddesc}[Context]{set_cipher_list}{ciphers}
865Set the list of ciphers to be used in this context. See the OpenSSL manual for
866more information (e.g. ciphers(1))
867\end{methoddesc}
868
869\begin{methoddesc}[Context]{set_info_callback}{callback}
870Set the information callback to \var{callback}. This function will be called
871from time to time during SSL handshakes.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500872\var{callback} should take three arguments: a Connection object and two
873integers. The first integer specifies where in the SSL handshake the function
874was called, and the other the return code from a (possibly failed) internal
875function call.
876\end{methoddesc}
877
878\begin{methoddesc}[Context]{set_options}{options}
879Add SSL options. Options you have set before are not cleared!
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500880This method should be used with the \constant{OP_*} constants.
881\end{methoddesc}
882
883\begin{methoddesc}[Context]{set_passwd_cb}{callback\optional{, userdata}}
884Set the passphrase callback to \var{callback}. This function will be called
Jean-Paul Calderone1eeb29e2008-10-19 11:50:53 -0400885when a private key with a passphrase is loaded. \var{callback} must accept
886three positional arguments. First, an integer giving the maximum length of
887the passphrase it may return. If the returned passphrase is longer than
888this, it will be truncated. Second, a boolean value which will be true if
889the user should be prompted for the passphrase twice and the callback should
890verify that the two values supplied are equal. Third, the value given as the
891\var{userdata} parameter to \method{set_passwd_cb}. If an error occurs,
892\var{callback} should return a false value (e.g. an empty string).
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500893\end{methoddesc}
894
895\begin{methoddesc}[Context]{set_session_id}{name}
896Set the context \var{name} within which a session can be reused for this
897Context object. This is needed when doing session resumption, because there is
898no way for a stored session to know which Context object it is associated with.
899\var{name} may be any binary data.
900\end{methoddesc}
901
902\begin{methoddesc}[Context]{set_timeout}{timeout}
903Set the timeout for newly created sessions for this Context object to
904\var{timeout}. \var{timeout} must be given in (whole) seconds. The default
905value is 300 seconds. See the OpenSSL manual for more information (e.g.
906SSL_CTX_set_timeout(3)).
907\end{methoddesc}
908
909\begin{methoddesc}[Context]{set_verify}{mode, callback}
910Set the verification flags for this Context object to \var{mode} and specify
911that \var{callback} should be used for verification callbacks. \var{mode}
912should be one of \constant{VERIFY_NONE} and \constant{VERIFY_PEER}. If
913\constant{VERIFY_PEER} is used, \var{mode} can be OR:ed with
914\constant{VERIFY_FAIL_IF_NO_PEER_CERT} and \constant{VERIFY_CLIENT_ONCE} to
915further control the behaviour.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500916\var{callback} should take five arguments: A Connection object, an X509 object,
917and three integer variables, which are in turn potential error number, error
918depth and return code. \var{callback} should return true if verification passes
919and false otherwise.
920\end{methoddesc}
921
922\begin{methoddesc}[Context]{set_verify_depth}{depth}
923Set the maximum depth for the certificate chain verification that shall be
924allowed for this Context object.
925\end{methoddesc}
926
927\begin{methoddesc}[Context]{use_certificate}{cert}
928Use the certificate \var{cert} which has to be a X509 object.
929\end{methoddesc}
930
Jean-Paul Calderone87b40602008-02-19 21:13:25 -0500931\begin{methoddesc}[Context]{add_extra_chain_cert}{cert}
932Adds the certificate \var{cert}, which has to be a X509 object, to the
933certificate chain presented together with the certificate.
934\end{methoddesc}
935
Jean-Paul Calderone897bc252008-02-18 20:50:23 -0500936\begin{methoddesc}[Context]{use_certificate_chain_file}{file}
937Load a certificate chain from \var{file} which must be PEM encoded.
938\end{methoddesc}
939
940\begin{methoddesc}[Context]{use_privatekey}{pkey}
941Use the private key \var{pkey} which has to be a PKey object.
942\end{methoddesc}
943
944\begin{methoddesc}[Context]{use_certificate_file}{file\optional{, format}}
945Load the first certificate found in \var{file}. The certificate must be in the
946format specified by \var{format}, which is either \constant{FILETYPE_PEM} or
947\constant{FILETYPE_ASN1}. The default is \constant{FILETYPE_PEM}.
948\end{methoddesc}
949
950\begin{methoddesc}[Context]{use_privatekey_file}{file\optional{, format}}
951Load the first private key found in \var{file}. The private key must be in the
952format specified by \var{format}, which is either \constant{FILETYPE_PEM} or
953\constant{FILETYPE_ASN1}. The default is \constant{FILETYPE_PEM}.
954\end{methoddesc}
955
956
957\subsubsection{Connection objects \label{openssl-connection}}
958
959Connection objects have the following methods:
960
961\begin{methoddesc}[Connection]{accept}{}
962Call the \method{accept} method of the underlying socket and set up SSL on the
963returned socket, using the Context object supplied to this Connection object at
964creation. Returns a pair \code{(\var{conn}, \var{address})}. where \var{conn}
965is the new Connection object created, and \var{address} is as returned by the
966socket's \method{accept}.
967\end{methoddesc}
968
969\begin{methoddesc}[Connection]{bind}{address}
970Call the \method{bind} method of the underlying socket.
971\end{methoddesc}
972
973\begin{methoddesc}[Connection]{close}{}
974Call the \method{close} method of the underlying socket. Note: If you want
975correct SSL closure, you need to call the \method{shutdown} method first.
976\end{methoddesc}
977
978\begin{methoddesc}[Connection]{connect}{address}
979Call the \method{connect} method of the underlying socket and set up SSL on the
980socket, using the Context object supplied to this Connection object at
981creation.
982\end{methoddesc}
983
984\begin{methoddesc}[Connection]{connect_ex}{address}
985Call the \method{connect_ex} method of the underlying socket and set up SSL on
986the socket, using the Context object supplied to this Connection object at
987creation. Note that if the \method{connect_ex} method of the socket doesn't
988return 0, SSL won't be initialized.
989\end{methoddesc}
990
991\begin{methoddesc}[Connection]{do_handshake}{}
992Perform an SSL handshake (usually called after \method{renegotiate} or one of
993\method{set_accept_state} or \method{set_accept_state}). This can raise the
994same exceptions as \method{send} and \method{recv}.
995\end{methoddesc}
996
997\begin{methoddesc}[Connection]{fileno}{}
998Retrieve the file descriptor number for the underlying socket.
999\end{methoddesc}
1000
1001\begin{methoddesc}[Connection]{listen}{backlog}
1002Call the \method{listen} method of the underlying socket.
1003\end{methoddesc}
1004
1005\begin{methoddesc}[Connection]{get_app_data}{}
1006Retrieve application data as set by \method{set_app_data}.
1007\end{methoddesc}
1008
1009\begin{methoddesc}[Connection]{get_cipher_list}{}
1010Retrieve the list of ciphers used by the Connection object. WARNING: This API
1011has changed. It used to take an optional parameter and just return a string,
1012but not it returns the entire list in one go.
1013\end{methoddesc}
1014
1015\begin{methoddesc}[Connection]{get_context}{}
1016Retrieve the Context object associated with this Connection.
1017\end{methoddesc}
1018
1019\begin{methoddesc}[Connection]{get_peer_certificate}{}
1020Retrieve the other side's certificate (if any)
1021\end{methoddesc}
1022
1023\begin{methoddesc}[Connection]{getpeername}{}
1024Call the \method{getpeername} method of the underlying socket.
1025\end{methoddesc}
1026
1027\begin{methoddesc}[Connection]{getsockname}{}
1028Call the \method{getsockname} method of the underlying socket.
1029\end{methoddesc}
1030
1031\begin{methoddesc}[Connection]{getsockopt}{level, optname\optional{, buflen}}
1032Call the \method{getsockopt} method of the underlying socket.
1033\end{methoddesc}
1034
1035\begin{methoddesc}[Connection]{pending}{}
Jean-Paul Calderoneb6f57be2008-03-06 21:22:16 -05001036Retrieve the number of bytes that can be safely read from the SSL buffer
1037(\emph{not} the underlying transport buffer).
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001038\end{methoddesc}
1039
1040\begin{methoddesc}[Connection]{recv}{bufsize}
1041Receive data from the Connection. The return value is a string representing the
1042data received. The maximum amount of data to be received at once, is specified
1043by \var{bufsize}.
1044\end{methoddesc}
1045
Jean-Paul Calderoneb6b17122009-05-01 16:36:11 -04001046\begin{methoddesc}[Connection]{bio_write}{bytes}
1047If the Connection was created with a memory BIO, this method can be used to add
1048bytes to the read end of that memory BIO. The Connection can then read the
1049bytes (for example, in response to a call to \method{recv}).
1050\end{methoddesc}
1051
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001052\begin{methoddesc}[Connection]{renegotiate}{}
1053Renegotiate the SSL session. Call this if you wish to change cipher suites or
1054anything like that.
1055\end{methoddesc}
1056
1057\begin{methoddesc}[Connection]{send}{string}
1058Send the \var{string} data to the Connection.
1059\end{methoddesc}
1060
Jean-Paul Calderoneb6b17122009-05-01 16:36:11 -04001061\begin{methoddesc}[Connection]{bio_read}{bufsize}
1062If the Connection was created with a memory BIO, this method can be used to
1063read bytes from the write end of that memory BIO. Many Connection methods will
1064add bytes which must be read in this manner or the buffer will eventually fill
1065up and the Connection will be able to take no further actions.
1066\end{methoddesc}
1067
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001068\begin{methoddesc}[Connection]{sendall}{string}
1069Send all of the \var{string} data to the Connection. This calls \method{send}
1070repeatedly until all data is sent. If an error occurs, it's impossible to tell
1071how much data has been sent.
1072\end{methoddesc}
1073
1074\begin{methoddesc}[Connection]{set_accept_state}{}
1075Set the connection to work in server mode. The handshake will be handled
1076automatically by read/write.
1077\end{methoddesc}
1078
1079\begin{methoddesc}[Connection]{set_app_data}{data}
1080Associate \var{data} with this Connection object. \var{data} can be retrieved
1081later using the \method{get_app_data} method.
1082\end{methoddesc}
1083
1084\begin{methoddesc}[Connection]{set_connect_state}{}
1085Set the connection to work in client mode. The handshake will be handled
1086automatically by read/write.
1087\end{methoddesc}
1088
1089\begin{methoddesc}[Connection]{setblocking}{flag}
1090Call the \method{setblocking} method of the underlying socket.
1091\end{methoddesc}
1092
1093\begin{methoddesc}[Connection]{setsockopt}{level, optname, value}
1094Call the \method{setsockopt} method of the underlying socket.
1095\end{methoddesc}
1096
1097\begin{methoddesc}[Connection]{shutdown}{}
1098Send the shutdown message to the Connection. Returns true if the shutdown
1099message exchange is completed and false otherwise (in which case you call
1100\method{recv()} or \method{send()} when the connection becomes
1101readable/writeable.
1102\end{methoddesc}
1103
Jean-Paul Calderone72b8f0f2008-02-21 23:57:40 -05001104\begin{methoddesc}[Connection]{get_shutdown}{}
1105Get the shutdown state of the Connection. Returns a bitvector of either or
1106both of \var{SENT_SHUTDOWN} and \var{RECEIVED_SHUTDOWN}.
1107\end{methoddesc}
1108
1109\begin{methoddesc}[Connection]{set_shutdown}{state}
1110Set the shutdown state of the Connection. \var{state} is a bitvector of
1111either or both of \var{SENT_SHUTDOWN} and \var{RECEIVED_SHUTDOWN}.
1112\end{methoddesc}
1113
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001114\begin{methoddesc}[Connection]{sock_shutdown}{how}
1115Call the \method{shutdown} method of the underlying socket.
1116\end{methoddesc}
1117
Jean-Paul Calderoneb6b17122009-05-01 16:36:11 -04001118\begin{methoddesc}[Connection]{bio_shutdown}{}
1119If the Connection was created with a memory BIO, this method can be used to
1120indicate that ``end of file'' has been reached on the read end of that memory
1121BIO.
1122\end{methoddesc}
1123
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001124\begin{methoddesc}[Connection]{state_string}{}
1125Retrieve a verbose string detailing the state of the Connection.
1126\end{methoddesc}
1127
Jean-Paul Calderonefd236f32009-05-03 19:45:07 -04001128\begin{methoddesc}[Connection]{client_random}{}
1129Retrieve the random value used with the client hello message.
1130\end{methoddesc}
1131
1132\begin{methoddesc}[Connection]{server_random}{}
1133Retrieve the random value used with the server hello message.
1134\end{methoddesc}
1135
1136\begin{methoddesc}[Connection]{master_key}{}
1137Retrieve the value of the master key for this session.
1138\end{methoddesc}
1139
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001140\begin{methoddesc}[Connection]{want_read}{}
1141Checks if more data has to be read from the transport layer to complete an
1142operation.
1143\end{methoddesc}
1144
1145\begin{methoddesc}[Connection]{want_write}{}
1146Checks if there is data to write to the transport layer to complete an
1147operation.
1148\end{methoddesc}
1149
1150
1151
1152\section{Internals \label{internals}}
1153
1154We ran into three main problems developing this: Exceptions, callbacks and
1155accessing socket methods. This is what this chapter is about.
1156
1157\subsection{Exceptions \label{exceptions}}
1158
1159We realized early that most of the exceptions would be raised by the I/O
1160functions of OpenSSL, so it felt natural to mimic OpenSSL's error code system,
1161translating them into Python exceptions. This naturally gives us the exceptions
1162\exception{SSL.ZeroReturnError}, \exception{SSL.WantReadError},
1163\exception{SSL.WantWriteError}, \exception{SSL.WantX509LookupError} and
1164\exception{SSL.SysCallError}.
1165
1166For more information about this, see section \ref{openssl-ssl}.
1167
1168
1169\subsection{Callbacks \label{callbacks}}
1170
1171There are a number of problems with callbacks. First of all, OpenSSL is written
1172as a C library, it's not meant to have Python callbacks, so a way around that
1173is needed. Another problem is thread support. A lot of the OpenSSL I/O
1174functions can block if the socket is in blocking mode, and then you want other
1175Python threads to be able to do other things. The real trouble is if you've
Jean-Paul Calderoneb7d6db22008-09-21 18:57:56 -04001176released the global CPython interpreter lock to do a potentially blocking
1177operation, and the operation calls a callback. Then we must take the GIL back,
1178since calling Python APIs without holding it is not allowed.
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001179
1180There are two solutions to the first problem, both of which are necessary. The
1181first solution to use is if the C callback allows ''userdata'' to be passed to
1182it (an arbitrary pointer normally). This is great! We can set our Python
1183function object as the real userdata and emulate userdata for the Python
1184function in another way. The other solution can be used if an object with an
1185''app_data'' system always is passed to the callback. For example, the SSL
1186object in OpenSSL has app_data functions and in e.g. the verification
1187callbacks, you can retrieve the related SSL object. What we do is to set our
1188wrapper \class{Connection} object as app_data for the SSL object, and we can
1189easily find the Python callback.
1190
Jean-Paul Calderoneb7d6db22008-09-21 18:57:56 -04001191The other problem is solved using thread local variables. Whenever the GIL is
1192released before calling into an OpenSSL API, the PyThreadState pointer returned
1193by \cfunction{PyEval_SaveState} is stored in a global thread local variable
1194(using Python's own TLS API, \cfunction{PyThread_set_key_value}). When it is
1195necessary to re-acquire the GIL, either after the OpenSSL API returns or in a C
1196callback invoked by that OpenSSL API, the value of the thread local variable is
1197retrieved (\cfunction{PyThread_get_key_value}) and used to re-acquire the GIL.
1198This allows Python threads to execute while OpenSSL APIs are running and allows
1199use of any particular pyOpenSSL object from any Python thread, since there is
1200no per-thread state associated with any of these objects and since OpenSSL is
1201threadsafe (as long as properly initialized, as pyOpenSSL initializes it).
Jean-Paul Calderone897bc252008-02-18 20:50:23 -05001202
1203
1204\subsection{Acessing Socket Methods \label{socket-methods}}
1205
1206We quickly saw the benefit of wrapping socket methods in the
1207\class{SSL.Connection} class, for an easy transition into using SSL. The
1208problem here is that the \module{socket} module lacks a C API, and all the
1209methods are declared static. One approach would be to have \module{OpenSSL} as
1210a submodule to the \module{socket} module, placing all the code in
1211\file{socketmodule.c}, but this is obviously not a good solution, since you
1212might not want to import tonnes of extra stuff you're not going to use when
1213importing the \module{socket} module. The other approach is to somehow get a
1214pointer to the method to be called, either the C function, or a callable Python
1215object. This is not really a good solution either, since there's a lot of
1216lookups involved.
1217
1218The way it works is that you have to supply a ``\class{socket}-like'' transport
1219object to the \class{SSL.Connection}. The only requirement of this object is
1220that it has a \method{fileno()} method that returns a file descriptor that's
1221valid at the C level (i.e. you can use the system calls read and write). If you
1222want to use the \method{connect()} or \method{accept()} methods of the
1223\class{SSL.Connection} object, the transport object has to supply such
1224methods too. Apart from them, any method lookups in the \class{SSL.Connection}
1225object that fail are passed on to the underlying transport object.
1226
1227Future changes might be to allow Python-level transport objects, that instead
1228of having \method{fileno()} methods, have \method{read()} and \method{write()}
1229methods, so more advanced features of Python can be used. This would probably
1230entail some sort of OpenSSL ``BIOs'', but converting Python strings back and
1231forth is expensive, so this shouldn't be used unless necessary. Other nice
1232things would be to be able to pass in different transport objects for reading
1233and writing, but then the \method{fileno()} method of \class{SSL.Connection}
1234becomes virtually useless. Also, should the method resolution be used on the
1235read-transport or the write-transport?
1236
1237
1238\end{document}