summaryrefslogtreecommitdiff
path: root/boost/asio/ssl/context.hpp
blob: 3cf2607737c3c53bd4f16e0eb19cc93164539f90 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
//
// ssl/context.hpp
// ~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2016 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef BOOST_ASIO_SSL_CONTEXT_HPP
#define BOOST_ASIO_SSL_CONTEXT_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include <boost/asio/detail/config.hpp>

#if defined(BOOST_ASIO_ENABLE_OLD_SSL)
# include <boost/asio/ssl/basic_context.hpp>
# include <boost/asio/ssl/context_service.hpp>
#else // defined(BOOST_ASIO_ENABLE_OLD_SSL)
# include <string>
# include <boost/asio/buffer.hpp>
# include <boost/asio/io_service.hpp>
# include <boost/asio/ssl/context_base.hpp>
# include <boost/asio/ssl/detail/openssl_types.hpp>
# include <boost/asio/ssl/detail/openssl_init.hpp>
# include <boost/asio/ssl/detail/password_callback.hpp>
# include <boost/asio/ssl/detail/verify_callback.hpp>
# include <boost/asio/ssl/verify_mode.hpp>
#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)

#include <boost/asio/detail/push_options.hpp>

namespace boost {
namespace asio {
namespace ssl {

#if defined(BOOST_ASIO_ENABLE_OLD_SSL)

/// Typedef for the typical usage of context.
typedef basic_context<context_service> context;

#else // defined(BOOST_ASIO_ENABLE_OLD_SSL)

class context
  : public context_base,
    private noncopyable
{
public:
  /// The native handle type of the SSL context.
  typedef SSL_CTX* native_handle_type;

  /// (Deprecated: Use native_handle_type.) The native type of the SSL context.
  typedef SSL_CTX* impl_type;

  /// Constructor.
  BOOST_ASIO_DECL explicit context(method m);

  /// Deprecated constructor taking a reference to an io_service object.
  BOOST_ASIO_DECL context(boost::asio::io_service&, method m);

#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
  /// Move-construct a context from another.
  /**
   * This constructor moves an SSL context from one object to another.
   *
   * @param other The other context object from which the move will occur.
   *
   * @note Following the move, the following operations only are valid for the
   * moved-from object:
   * @li Destruction.
   * @li As a target for move-assignment.
   */
  BOOST_ASIO_DECL context(context&& other);

  /// Move-assign a context from another.
  /**
   * This assignment operator moves an SSL context from one object to another.
   *
   * @param other The other context object from which the move will occur.
   *
   * @note Following the move, the following operations only are valid for the
   * moved-from object:
   * @li Destruction.
   * @li As a target for move-assignment.
   */
  BOOST_ASIO_DECL context& operator=(context&& other);
#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)

  /// Destructor.
  BOOST_ASIO_DECL ~context();

  /// Get the underlying implementation in the native type.
  /**
   * This function may be used to obtain the underlying implementation of the
   * context. This is intended to allow access to context functionality that is
   * not otherwise provided.
   */
  BOOST_ASIO_DECL native_handle_type native_handle();

  /// (Deprecated: Use native_handle().) Get the underlying implementation in
  /// the native type.
  /**
   * This function may be used to obtain the underlying implementation of the
   * context. This is intended to allow access to context functionality that is
   * not otherwise provided.
   */
  BOOST_ASIO_DECL impl_type impl();

  /// Clear options on the context.
  /**
   * This function may be used to configure the SSL options used by the context.
   *
   * @param o A bitmask of options. The available option values are defined in
   * the context_base class. The specified options, if currently enabled on the
   * context, are cleared.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_clear_options.
   */
  BOOST_ASIO_DECL void clear_options(options o);

  /// Clear options on the context.
  /**
   * This function may be used to configure the SSL options used by the context.
   *
   * @param o A bitmask of options. The available option values are defined in
   * the context_base class. The specified options, if currently enabled on the
   * context, are cleared.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_clear_options.
   */
  BOOST_ASIO_DECL boost::system::error_code clear_options(options o,
      boost::system::error_code& ec);

  /// Set options on the context.
  /**
   * This function may be used to configure the SSL options used by the context.
   *
   * @param o A bitmask of options. The available option values are defined in
   * the context_base class. The options are bitwise-ored with any existing
   * value for the options.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_set_options.
   */
  BOOST_ASIO_DECL void set_options(options o);

  /// Set options on the context.
  /**
   * This function may be used to configure the SSL options used by the context.
   *
   * @param o A bitmask of options. The available option values are defined in
   * the context_base class. The options are bitwise-ored with any existing
   * value for the options.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_set_options.
   */
  BOOST_ASIO_DECL boost::system::error_code set_options(options o,
      boost::system::error_code& ec);

  /// Set the peer verification mode.
  /**
   * This function may be used to configure the peer verification mode used by
   * the context.
   *
   * @param v A bitmask of peer verification modes. See @ref verify_mode for
   * available values.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_set_verify.
   */
  BOOST_ASIO_DECL void set_verify_mode(verify_mode v);

  /// Set the peer verification mode.
  /**
   * This function may be used to configure the peer verification mode used by
   * the context.
   *
   * @param v A bitmask of peer verification modes. See @ref verify_mode for
   * available values.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_set_verify.
   */
  BOOST_ASIO_DECL boost::system::error_code set_verify_mode(
      verify_mode v, boost::system::error_code& ec);

  /// Set the peer verification depth.
  /**
   * This function may be used to configure the maximum verification depth
   * allowed by the context.
   *
   * @param depth Maximum depth for the certificate chain verification that
   * shall be allowed.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_set_verify_depth.
   */
  BOOST_ASIO_DECL void set_verify_depth(int depth);

  /// Set the peer verification depth.
  /**
   * This function may be used to configure the maximum verification depth
   * allowed by the context.
   *
   * @param depth Maximum depth for the certificate chain verification that
   * shall be allowed.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_set_verify_depth.
   */
  BOOST_ASIO_DECL boost::system::error_code set_verify_depth(
      int depth, boost::system::error_code& ec);

  /// Set the callback used to verify peer certificates.
  /**
   * This function is used to specify a callback function that will be called
   * by the implementation when it needs to verify a peer certificate.
   *
   * @param callback The function object to be used for verifying a certificate.
   * The function signature of the handler must be:
   * @code bool verify_callback(
   *   bool preverified, // True if the certificate passed pre-verification.
   *   verify_context& ctx // The peer certificate and other context.
   * ); @endcode
   * The return value of the callback is true if the certificate has passed
   * verification, false otherwise.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_set_verify.
   */
  template <typename VerifyCallback>
  void set_verify_callback(VerifyCallback callback);

  /// Set the callback used to verify peer certificates.
  /**
   * This function is used to specify a callback function that will be called
   * by the implementation when it needs to verify a peer certificate.
   *
   * @param callback The function object to be used for verifying a certificate.
   * The function signature of the handler must be:
   * @code bool verify_callback(
   *   bool preverified, // True if the certificate passed pre-verification.
   *   verify_context& ctx // The peer certificate and other context.
   * ); @endcode
   * The return value of the callback is true if the certificate has passed
   * verification, false otherwise.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_set_verify.
   */
  template <typename VerifyCallback>
  boost::system::error_code set_verify_callback(VerifyCallback callback,
      boost::system::error_code& ec);

  /// Load a certification authority file for performing verification.
  /**
   * This function is used to load one or more trusted certification authorities
   * from a file.
   *
   * @param filename The name of a file containing certification authority
   * certificates in PEM format.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_load_verify_locations.
   */
  BOOST_ASIO_DECL void load_verify_file(const std::string& filename);

  /// Load a certification authority file for performing verification.
  /**
   * This function is used to load the certificates for one or more trusted
   * certification authorities from a file.
   *
   * @param filename The name of a file containing certification authority
   * certificates in PEM format.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_load_verify_locations.
   */
  BOOST_ASIO_DECL boost::system::error_code load_verify_file(
      const std::string& filename, boost::system::error_code& ec);

  /// Add certification authority for performing verification.
  /**
   * This function is used to add one trusted certification authority
   * from a memory buffer.
   *
   * @param ca The buffer containing the certification authority certificate.
   * The certificate must use the PEM format.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_get_cert_store and @c X509_STORE_add_cert.
   */
  BOOST_ASIO_DECL void add_certificate_authority(const const_buffer& ca);

  /// Add certification authority for performing verification.
  /**
   * This function is used to add one trusted certification authority
   * from a memory buffer.
   *
   * @param ca The buffer containing the certification authority certificate.
   * The certificate must use the PEM format.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_get_cert_store and @c X509_STORE_add_cert.
   */
  BOOST_ASIO_DECL boost::system::error_code add_certificate_authority(
      const const_buffer& ca, boost::system::error_code& ec);

  /// Configures the context to use the default directories for finding
  /// certification authority certificates.
  /**
   * This function specifies that the context should use the default,
   * system-dependent directories for locating certification authority
   * certificates.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_set_default_verify_paths.
   */
  BOOST_ASIO_DECL void set_default_verify_paths();

  /// Configures the context to use the default directories for finding
  /// certification authority certificates.
  /**
   * This function specifies that the context should use the default,
   * system-dependent directories for locating certification authority
   * certificates.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_set_default_verify_paths.
   */
  BOOST_ASIO_DECL boost::system::error_code set_default_verify_paths(
      boost::system::error_code& ec);

  /// Add a directory containing certificate authority files to be used for
  /// performing verification.
  /**
   * This function is used to specify the name of a directory containing
   * certification authority certificates. Each file in the directory must
   * contain a single certificate. The files must be named using the subject
   * name's hash and an extension of ".0".
   *
   * @param path The name of a directory containing the certificates.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_load_verify_locations.
   */
  BOOST_ASIO_DECL void add_verify_path(const std::string& path);

  /// Add a directory containing certificate authority files to be used for
  /// performing verification.
  /**
   * This function is used to specify the name of a directory containing
   * certification authority certificates. Each file in the directory must
   * contain a single certificate. The files must be named using the subject
   * name's hash and an extension of ".0".
   *
   * @param path The name of a directory containing the certificates.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_load_verify_locations.
   */
  BOOST_ASIO_DECL boost::system::error_code add_verify_path(
      const std::string& path, boost::system::error_code& ec);

  /// Use a certificate from a memory buffer.
  /**
   * This function is used to load a certificate into the context from a buffer.
   *
   * @param certificate The buffer containing the certificate.
   *
   * @param format The certificate format (ASN.1 or PEM).
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_use_certificate or SSL_CTX_use_certificate_ASN1.
   */
  BOOST_ASIO_DECL void use_certificate(
      const const_buffer& certificate, file_format format);

  /// Use a certificate from a memory buffer.
  /**
   * This function is used to load a certificate into the context from a buffer.
   *
   * @param certificate The buffer containing the certificate.
   *
   * @param format The certificate format (ASN.1 or PEM).
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_use_certificate or SSL_CTX_use_certificate_ASN1.
   */
  BOOST_ASIO_DECL boost::system::error_code use_certificate(
      const const_buffer& certificate, file_format format,
      boost::system::error_code& ec);

  /// Use a certificate from a file.
  /**
   * This function is used to load a certificate into the context from a file.
   *
   * @param filename The name of the file containing the certificate.
   *
   * @param format The file format (ASN.1 or PEM).
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_use_certificate_file.
   */
  BOOST_ASIO_DECL void use_certificate_file(
      const std::string& filename, file_format format);

  /// Use a certificate from a file.
  /**
   * This function is used to load a certificate into the context from a file.
   *
   * @param filename The name of the file containing the certificate.
   *
   * @param format The file format (ASN.1 or PEM).
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_use_certificate_file.
   */
  BOOST_ASIO_DECL boost::system::error_code use_certificate_file(
      const std::string& filename, file_format format,
      boost::system::error_code& ec);

  /// Use a certificate chain from a memory buffer.
  /**
   * This function is used to load a certificate chain into the context from a
   * buffer.
   *
   * @param chain The buffer containing the certificate chain. The certificate
   * chain must use the PEM format.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_use_certificate and SSL_CTX_add_extra_chain_cert.
   */
  BOOST_ASIO_DECL void use_certificate_chain(const const_buffer& chain);

  /// Use a certificate chain from a memory buffer.
  /**
   * This function is used to load a certificate chain into the context from a
   * buffer.
   *
   * @param chain The buffer containing the certificate chain. The certificate
   * chain must use the PEM format.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_use_certificate and SSL_CTX_add_extra_chain_cert.
   */
  BOOST_ASIO_DECL boost::system::error_code use_certificate_chain(
      const const_buffer& chain, boost::system::error_code& ec);

  /// Use a certificate chain from a file.
  /**
   * This function is used to load a certificate chain into the context from a
   * file.
   *
   * @param filename The name of the file containing the certificate. The file
   * must use the PEM format.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_use_certificate_chain_file.
   */
  BOOST_ASIO_DECL void use_certificate_chain_file(const std::string& filename);

  /// Use a certificate chain from a file.
  /**
   * This function is used to load a certificate chain into the context from a
   * file.
   *
   * @param filename The name of the file containing the certificate. The file
   * must use the PEM format.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_use_certificate_chain_file.
   */
  BOOST_ASIO_DECL boost::system::error_code use_certificate_chain_file(
      const std::string& filename, boost::system::error_code& ec);

  /// Use a private key from a memory buffer.
  /**
   * This function is used to load a private key into the context from a buffer.
   *
   * @param private_key The buffer containing the private key.
   *
   * @param format The private key format (ASN.1 or PEM).
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_use_PrivateKey or SSL_CTX_use_PrivateKey_ASN1.
   */
  BOOST_ASIO_DECL void use_private_key(
      const const_buffer& private_key, file_format format);

  /// Use a private key from a memory buffer.
  /**
   * This function is used to load a private key into the context from a buffer.
   *
   * @param private_key The buffer containing the private key.
   *
   * @param format The private key format (ASN.1 or PEM).
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_use_PrivateKey or SSL_CTX_use_PrivateKey_ASN1.
   */
  BOOST_ASIO_DECL boost::system::error_code use_private_key(
      const const_buffer& private_key, file_format format,
      boost::system::error_code& ec);

  /// Use a private key from a file.
  /**
   * This function is used to load a private key into the context from a file.
   *
   * @param filename The name of the file containing the private key.
   *
   * @param format The file format (ASN.1 or PEM).
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_use_PrivateKey_file.
   */
  BOOST_ASIO_DECL void use_private_key_file(
      const std::string& filename, file_format format);

  /// Use a private key from a file.
  /**
   * This function is used to load a private key into the context from a file.
   *
   * @param filename The name of the file containing the private key.
   *
   * @param format The file format (ASN.1 or PEM).
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_use_PrivateKey_file.
   */
  BOOST_ASIO_DECL boost::system::error_code use_private_key_file(
      const std::string& filename, file_format format,
      boost::system::error_code& ec);

  /// Use an RSA private key from a memory buffer.
  /**
   * This function is used to load an RSA private key into the context from a
   * buffer.
   *
   * @param private_key The buffer containing the RSA private key.
   *
   * @param format The private key format (ASN.1 or PEM).
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_use_RSAPrivateKey or SSL_CTX_use_RSAPrivateKey_ASN1.
   */
  BOOST_ASIO_DECL void use_rsa_private_key(
      const const_buffer& private_key, file_format format);

  /// Use an RSA private key from a memory buffer.
  /**
   * This function is used to load an RSA private key into the context from a
   * buffer.
   *
   * @param private_key The buffer containing the RSA private key.
   *
   * @param format The private key format (ASN.1 or PEM).
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_use_RSAPrivateKey or SSL_CTX_use_RSAPrivateKey_ASN1.
   */
  BOOST_ASIO_DECL boost::system::error_code use_rsa_private_key(
      const const_buffer& private_key, file_format format,
      boost::system::error_code& ec);

  /// Use an RSA private key from a file.
  /**
   * This function is used to load an RSA private key into the context from a
   * file.
   *
   * @param filename The name of the file containing the RSA private key.
   *
   * @param format The file format (ASN.1 or PEM).
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_use_RSAPrivateKey_file.
   */
  BOOST_ASIO_DECL void use_rsa_private_key_file(
      const std::string& filename, file_format format);

  /// Use an RSA private key from a file.
  /**
   * This function is used to load an RSA private key into the context from a
   * file.
   *
   * @param filename The name of the file containing the RSA private key.
   *
   * @param format The file format (ASN.1 or PEM).
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_use_RSAPrivateKey_file.
   */
  BOOST_ASIO_DECL boost::system::error_code use_rsa_private_key_file(
      const std::string& filename, file_format format,
      boost::system::error_code& ec);

  /// Use the specified memory buffer to obtain the temporary Diffie-Hellman
  /// parameters.
  /**
   * This function is used to load Diffie-Hellman parameters into the context
   * from a buffer.
   *
   * @param dh The memory buffer containing the Diffie-Hellman parameters. The
   * buffer must use the PEM format.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_set_tmp_dh.
   */
  BOOST_ASIO_DECL void use_tmp_dh(const const_buffer& dh);

  /// Use the specified memory buffer to obtain the temporary Diffie-Hellman
  /// parameters.
  /**
   * This function is used to load Diffie-Hellman parameters into the context
   * from a buffer.
   *
   * @param dh The memory buffer containing the Diffie-Hellman parameters. The
   * buffer must use the PEM format.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_set_tmp_dh.
   */
  BOOST_ASIO_DECL boost::system::error_code use_tmp_dh(
      const const_buffer& dh, boost::system::error_code& ec);

  /// Use the specified file to obtain the temporary Diffie-Hellman parameters.
  /**
   * This function is used to load Diffie-Hellman parameters into the context
   * from a file.
   *
   * @param filename The name of the file containing the Diffie-Hellman
   * parameters. The file must use the PEM format.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_set_tmp_dh.
   */
  BOOST_ASIO_DECL void use_tmp_dh_file(const std::string& filename);

  /// Use the specified file to obtain the temporary Diffie-Hellman parameters.
  /**
   * This function is used to load Diffie-Hellman parameters into the context
   * from a file.
   *
   * @param filename The name of the file containing the Diffie-Hellman
   * parameters. The file must use the PEM format.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_set_tmp_dh.
   */
  BOOST_ASIO_DECL boost::system::error_code use_tmp_dh_file(
      const std::string& filename, boost::system::error_code& ec);

  /// Set the password callback.
  /**
   * This function is used to specify a callback function to obtain password
   * information about an encrypted key in PEM format.
   *
   * @param callback The function object to be used for obtaining the password.
   * The function signature of the handler must be:
   * @code std::string password_callback(
   *   std::size_t max_length,  // The maximum size for a password.
   *   password_purpose purpose // Whether password is for reading or writing.
   * ); @endcode
   * The return value of the callback is a string containing the password.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @note Calls @c SSL_CTX_set_default_passwd_cb.
   */
  template <typename PasswordCallback>
  void set_password_callback(PasswordCallback callback);

  /// Set the password callback.
  /**
   * This function is used to specify a callback function to obtain password
   * information about an encrypted key in PEM format.
   *
   * @param callback The function object to be used for obtaining the password.
   * The function signature of the handler must be:
   * @code std::string password_callback(
   *   std::size_t max_length,  // The maximum size for a password.
   *   password_purpose purpose // Whether password is for reading or writing.
   * ); @endcode
   * The return value of the callback is a string containing the password.
   *
   * @param ec Set to indicate what error occurred, if any.
   *
   * @note Calls @c SSL_CTX_set_default_passwd_cb.
   */
  template <typename PasswordCallback>
  boost::system::error_code set_password_callback(PasswordCallback callback,
      boost::system::error_code& ec);

private:
  struct bio_cleanup;
  struct x509_cleanup;
  struct evp_pkey_cleanup;
  struct rsa_cleanup;
  struct dh_cleanup;

  // Helper function used to set a peer certificate verification callback.
  BOOST_ASIO_DECL boost::system::error_code do_set_verify_callback(
      detail::verify_callback_base* callback, boost::system::error_code& ec);

  // Callback used when the SSL implementation wants to verify a certificate.
  BOOST_ASIO_DECL static int verify_callback_function(
      int preverified, X509_STORE_CTX* ctx);

  // Helper function used to set a password callback.
  BOOST_ASIO_DECL boost::system::error_code do_set_password_callback(
      detail::password_callback_base* callback, boost::system::error_code& ec);

  // Callback used when the SSL implementation wants a password.
  BOOST_ASIO_DECL static int password_callback_function(
      char* buf, int size, int purpose, void* data);

  // Helper function to set the temporary Diffie-Hellman parameters from a BIO.
  BOOST_ASIO_DECL boost::system::error_code do_use_tmp_dh(
      BIO* bio, boost::system::error_code& ec);

  // Helper function to make a BIO from a memory buffer.
  BOOST_ASIO_DECL BIO* make_buffer_bio(const const_buffer& b);

  // The underlying native implementation.
  native_handle_type handle_;

  // Ensure openssl is initialised.
  boost::asio::ssl::detail::openssl_init<> init_;
};

#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)

} // namespace ssl
} // namespace asio
} // namespace boost

#include <boost/asio/detail/pop_options.hpp>

#include <boost/asio/ssl/impl/context.hpp>
#if defined(BOOST_ASIO_HEADER_ONLY)
# include <boost/asio/ssl/impl/context.ipp>
#endif // defined(BOOST_ASIO_HEADER_ONLY)

#endif // BOOST_ASIO_SSL_CONTEXT_HPP