. /include/boost/corosio /tls_context.hpp
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1   // 1   //
2   // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com) 2   // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3   // Copyright (c) 2026 Michael Vandeberg 3   // Copyright (c) 2026 Michael Vandeberg
4   // 4   //
5   // Distributed under the Boost Software License, Version 1.0. (See accompanying 5   // Distributed under the Boost Software License, Version 1.0. (See accompanying
6   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 6   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7   // 7   //
8   // Official repository: https://github.com/cppalliance/corosio 8   // Official repository: https://github.com/cppalliance/corosio
9   // 9   //
10   10  
11   #ifndef BOOST_COROSIO_TLS_CONTEXT_HPP 11   #ifndef BOOST_COROSIO_TLS_CONTEXT_HPP
12   #define BOOST_COROSIO_TLS_CONTEXT_HPP 12   #define BOOST_COROSIO_TLS_CONTEXT_HPP
13   13  
14   #include <boost/corosio/detail/config.hpp> 14   #include <boost/corosio/detail/config.hpp>
15   15  
16   #include <cstddef> 16   #include <cstddef>
17   #include <functional> 17   #include <functional>
18   #include <span> 18   #include <span>
19   #include <system_error> 19   #include <system_error>
20   #include <memory> 20   #include <memory>
21   #include <string_view> 21   #include <string_view>
22   22  
23   namespace boost::corosio { 23   namespace boost::corosio {
24   24  
25   // 25   //
26   // Enumerations 26   // Enumerations
27   // 27   //
28   28  
29   /** TLS protocol version. 29   /** TLS protocol version.
30   30  
31   Specifies the minimum or maximum TLS protocol version to use 31   Specifies the minimum or maximum TLS protocol version to use
32   for connections. Only modern, secure versions are supported. 32   for connections. Only modern, secure versions are supported.
33   33  
34   @see tls_context::set_min_protocol_version 34   @see tls_context::set_min_protocol_version
35   @see tls_context::set_max_protocol_version 35   @see tls_context::set_max_protocol_version
36   */ 36   */
37   enum class tls_version 37   enum class tls_version
38   { 38   {
39   /// TLS 1.2 (RFC 5246). 39   /// TLS 1.2 (RFC 5246).
40   tls_1_2, 40   tls_1_2,
41   41  
42   /// TLS 1.3 (RFC 8446). 42   /// TLS 1.3 (RFC 8446).
43   tls_1_3 43   tls_1_3
44   }; 44   };
45   45  
46   /** Certificate and key file format. 46   /** Certificate and key file format.
47   47  
48   Specifies the encoding format for certificate and key data. 48   Specifies the encoding format for certificate and key data.
49   49  
50   @see tls_context::use_certificate 50   @see tls_context::use_certificate
51   @see tls_context::use_private_key 51   @see tls_context::use_private_key
52   */ 52   */
53   enum class tls_file_format 53   enum class tls_file_format
54   { 54   {
55   /// PEM format (Base64-encoded with header/footer lines). 55   /// PEM format (Base64-encoded with header/footer lines).
56   pem, 56   pem,
57   57  
58   /// DER format (raw ASN.1 binary encoding). 58   /// DER format (raw ASN.1 binary encoding).
59   der 59   der
60   }; 60   };
61   61  
62   /** Peer certificate verification mode. 62   /** Peer certificate verification mode.
63   63  
64   Controls how the TLS implementation verifies the peer's 64   Controls how the TLS implementation verifies the peer's
65   certificate during the handshake. 65   certificate during the handshake.
66   66  
67   @see tls_context::set_verify_mode 67   @see tls_context::set_verify_mode
68   */ 68   */
69   enum class tls_verify_mode 69   enum class tls_verify_mode
70   { 70   {
71   /// Do not request or verify the peer certificate. 71   /// Do not request or verify the peer certificate.
72   none, 72   none,
73   73  
74   /// Request and verify the peer certificate if presented. 74   /// Request and verify the peer certificate if presented.
75   peer, 75   peer,
76   76  
77   /// Require and verify the peer certificate (fail if not presented). 77   /// Require and verify the peer certificate (fail if not presented).
78   require_peer 78   require_peer
79   }; 79   };
80   80  
81   /** Certificate revocation checking policy. 81   /** Certificate revocation checking policy.
82   82  
83   Controls how certificate revocation status is checked during 83   Controls how certificate revocation status is checked during
84   verification. 84   verification.
85   85  
86   @see tls_context::set_revocation_policy 86   @see tls_context::set_revocation_policy
87   */ 87   */
88   enum class tls_revocation_policy 88   enum class tls_revocation_policy
89   { 89   {
90   /// Do not check revocation status. 90   /// Do not check revocation status.
91   disabled, 91   disabled,
92   92  
93   /// Check revocation but allow connection if status is unknown. 93   /// Check revocation but allow connection if status is unknown.
94   soft_fail, 94   soft_fail,
95   95  
96   /// Require successful revocation check (fail if status is unknown). 96   /// Require successful revocation check (fail if status is unknown).
97   hard_fail 97   hard_fail
98   }; 98   };
99   99  
100   /** Purpose for password callback invocation. 100   /** Purpose for password callback invocation.
101   101  
102   Indicates whether the password is needed for reading (decrypting) 102   Indicates whether the password is needed for reading (decrypting)
103   or writing (encrypting) key material. 103   or writing (encrypting) key material.
104   104  
105   @see tls_context::set_password_callback 105   @see tls_context::set_password_callback
106   */ 106   */
107   enum class tls_password_purpose 107   enum class tls_password_purpose
108   { 108   {
109   /// Password needed to decrypt/read protected key material. 109   /// Password needed to decrypt/read protected key material.
110   for_reading, 110   for_reading,
111   111  
112   /// Password needed to encrypt/write protected key material. 112   /// Password needed to encrypt/write protected key material.
113   for_writing 113   for_writing
114   }; 114   };
115   115  
116   class tls_context; 116   class tls_context;
117   117  
118 - /** A non-owning view of certificate verification state. 118 + /** Exposes the certificate and error state to a verification callback.
119   119  
120   An instance is passed to the callback installed via 120   An instance is passed to the callback installed via
121   tls_context::set_verify_callback during the TLS handshake. It 121   tls_context::set_verify_callback during the TLS handshake. It
122   exposes the backend's native verification handle so the callback 122   exposes the backend's native verification handle so the callback
123   can inspect the certificate and chain currently being verified. 123   can inspect the certificate and chain currently being verified.
124   124  
125   The value returned by native_handle() is, for the OpenSSL and 125   The value returned by native_handle() is, for the OpenSSL and
126   WolfSSL backends, an `X509_STORE_CTX*`. For portable inspection that 126   WolfSSL backends, an `X509_STORE_CTX*`. For portable inspection that
127   works across backends (for example certificate pinning), prefer 127   works across backends (for example certificate pinning), prefer
128   certificate(), which returns the DER encoding of the certificate 128   certificate(), which returns the DER encoding of the certificate
129   currently being verified. 129   currently being verified.
130   130  
131   @par Lifetime 131   @par Lifetime
132   132  
133   The wrapped handle and the certificate() bytes are owned by the TLS 133   The wrapped handle and the certificate() bytes are owned by the TLS
134   backend and are valid only for the duration of a single callback 134   backend and are valid only for the duration of a single callback
135   invocation. Do not retain them beyond the call. 135   invocation. Do not retain them beyond the call.
136   136  
137   @see tls_context::set_verify_callback 137   @see tls_context::set_verify_callback
138   */ 138   */
139   class verify_context 139   class verify_context
140   { 140   {
141   void* handle_; 141   void* handle_;
142   unsigned char const* der_; 142   unsigned char const* der_;
143   std::size_t der_len_; 143   std::size_t der_len_;
144   144  
145   public: 145   public:
146   /** Construct from a native handle and the current certificate. 146   /** Construct from a native handle and the current certificate.
147   147  
148   @param handle The backend verification handle (for OpenSSL and 148   @param handle The backend verification handle (for OpenSSL and
149   WolfSSL, an `X509_STORE_CTX*`). 149   WolfSSL, an `X509_STORE_CTX*`).
150   @param der Pointer to the DER encoding of the certificate under 150   @param der Pointer to the DER encoding of the certificate under
151   verification, or `nullptr` if unavailable. 151   verification, or `nullptr` if unavailable.
152   @param der_len Length of the DER encoding in bytes. 152   @param der_len Length of the DER encoding in bytes.
153   */ 153   */
154   verify_context( 154   verify_context(
155   void* handle, unsigned char const* der, std::size_t der_len) noexcept 155   void* handle, unsigned char const* der, std::size_t der_len) noexcept
156   : handle_(handle) 156   : handle_(handle)
157   , der_(der) 157   , der_(der)
158   , der_len_(der_len) 158   , der_len_(der_len)
159   { 159   {
160   } 160   }
161   161  
162   /** Return the native verification handle. 162   /** Return the native verification handle.
163   163  
164   Cast the result to the backend's verification context type 164   Cast the result to the backend's verification context type
165   (e.g. `X509_STORE_CTX*`) to inspect the certificate chain using 165   (e.g. `X509_STORE_CTX*`) to inspect the certificate chain using
166   backend-specific APIs. 166   backend-specific APIs.
167   167  
168   @return The native handle, or `nullptr` if none is available. 168   @return The native handle, or `nullptr` if none is available.
169   */ 169   */
170   void* native_handle() const noexcept 170   void* native_handle() const noexcept
171   { 171   {
172   return handle_; 172   return handle_;
173   } 173   }
174   174  
175   /** Return the DER encoding of the certificate being verified. 175   /** Return the DER encoding of the certificate being verified.
176   176  
177   This is the portable way to inspect the peer certificate from a 177   This is the portable way to inspect the peer certificate from a
178 - verification callback: it works identically on every backend, 178 + verification callback. It works identically on every backend,
179   without depending on backend-specific build options. A DER 179   without depending on backend-specific build options. A DER
180   certificate is an ASN.1 `SEQUENCE`, so the first byte is `0x30`. 180   certificate is an ASN.1 `SEQUENCE`, so the first byte is `0x30`.
181   181  
182   @return A view of the certificate's DER bytes, valid only for the 182   @return A view of the certificate's DER bytes, valid only for the
183   duration of the callback. Empty if the certificate is not 183   duration of the callback. Empty if the certificate is not
184   available. 184   available.
185   */ 185   */
MISUBC 186   ✗ std::span<unsigned char const> certificate() const noexcept 186   ✗ std::span<unsigned char const> certificate() const noexcept
187   { 187   {
MISUBC 188   ✗ return {der_, der_len_}; 188   ✗ return {der_, der_len_};
189   } 189   }
190   }; 190   };
191   191  
192   namespace detail { 192   namespace detail {
193   struct tls_context_data; 193   struct tls_context_data;
194   tls_context_data const& get_tls_context_data(tls_context const&) noexcept; 194   tls_context_data const& get_tls_context_data(tls_context const&) noexcept;
195   } // namespace detail 195   } // namespace detail
196   196  
197   #ifdef _MSC_VER 197   #ifdef _MSC_VER
198   #pragma warning(push) 198   #pragma warning(push)
199   #pragma warning(disable : 4251) // shared_ptr needs dll-interface 199   #pragma warning(disable : 4251) // shared_ptr needs dll-interface
200   #endif 200   #endif
201   201  
202 - /** A portable TLS context for certificate and settings storage. 202 + /** Configures the certificates, keys, and protocol settings a TLS stream uses.
203   203  
204   The `tls_context` class provides a backend-agnostic interface for 204   The `tls_context` class provides a backend-agnostic interface for
205   configuring TLS connections. It stores credentials (certificates and 205   configuring TLS connections. It stores credentials (certificates and
206   private keys), trust anchors, protocol settings, and verification 206   private keys), trust anchors, protocol settings, and verification
207   options that are used when establishing TLS connections. 207   options that are used when establishing TLS connections.
208   208  
209   This class is a shared handle to an opaque implementation. Copies 209   This class is a shared handle to an opaque implementation. Copies
210   share the same underlying state. This allows contexts to be passed 210   share the same underlying state. This allows contexts to be passed
211   by value and shared across multiple TLS streams. 211   by value and shared across multiple TLS streams.
212   212  
213   This class abstracts the configuration phase of TLS across multiple 213   This class abstracts the configuration phase of TLS across multiple
214 - backend implementations (OpenSSL, WolfSSL, mbedTLS, Schannel, etc.), 214 + backend implementations, among them OpenSSL, WolfSSL, mbedTLS and
215 - allowing portable code that works regardless of which TLS library 215 + Schannel. Portable code therefore works regardless of which TLS
216 - is linked. 216 + library is linked.
217   217  
218   @par Modification After Stream Creation 218   @par Modification After Stream Creation
219   219  
220 - Modifying a context after a TLS stream has been created from it 220 + Modifying a context after creating a TLS stream from it
221   results in undefined behavior. The context's configuration is 221   results in undefined behavior. The context's configuration is
222   captured when the first stream is constructed, and subsequent 222   captured when the first stream is constructed, and subsequent
223   modifications are not reflected in existing or new streams 223   modifications are not reflected in existing or new streams
224   sharing the context. 224   sharing the context.
225   225  
226   If different configurations are needed, create separate context 226   If different configurations are needed, create separate context
227   objects. 227   objects.
228   228  
229   @par Thread Safety 229   @par Thread Safety
230   230  
231   Distinct objects: Safe. 231   Distinct objects: Safe.
232   232  
233   Shared objects: Unsafe. A context must not be modified while 233   Shared objects: Unsafe. A context must not be modified while
234   any thread is creating streams from it. 234   any thread is creating streams from it.
235   235  
236   @par Example 236   @par Example
237   @par !example tls_context 237   @par !example tls_context
238   238  
239   @see tls_role 239   @see tls_role
240   */ 240   */
241   class BOOST_COROSIO_DECL tls_context 241   class BOOST_COROSIO_DECL tls_context
242   { 242   {
243   struct implementation; 243   struct implementation;
244   std::shared_ptr<implementation> impl_; 244   std::shared_ptr<implementation> impl_;
245   245  
246   friend detail::tls_context_data const& 246   friend detail::tls_context_data const&
247   detail::get_tls_context_data(tls_context const&) noexcept; 247   detail::get_tls_context_data(tls_context const&) noexcept;
248   248  
249   public: 249   public:
250   /** Construct a default TLS context. 250   /** Construct a default TLS context.
251   251  
252   Creates a context with default settings suitable for TLS 1.2 252   Creates a context with default settings suitable for TLS 1.2
253   and TLS 1.3 connections. No certificates or trust anchors are 253   and TLS 1.3 connections. No certificates or trust anchors are
254   loaded; call the appropriate methods to configure credentials 254   loaded; call the appropriate methods to configure credentials
255   and verification. 255   and verification.
256   256  
257   @par Example 257   @par Example
258   @par !example tls_context 258   @par !example tls_context
259   */ 259   */
260   tls_context(); 260   tls_context();
261   261  
262 - /** Copy constructor. 262 + /** Creates a new handle that shares ownership of the underlying
263 -  
264 - Creates a new handle that shares ownership of the underlying  
265   TLS context state with `other`. 263   TLS context state with `other`.
266   264  
267   @param other The context to copy from. 265   @param other The context to copy from.
268   */ 266   */
HITCBC 269   2 tls_context(tls_context const& other) = default; 267   2 tls_context(tls_context const& other) = default;
270   268  
271 - /** Copy assignment operator. 269 + /** Releases the current context's shared ownership and acquires
272 -  
273 - Releases the current context's shared ownership and acquires  
274   shared ownership of `other`'s underlying state. 270   shared ownership of `other`'s underlying state.
275   271  
276   @param other The context to copy from. 272   @param other The context to copy from.
277   273  
278   @return Reference to this context. 274   @return Reference to this context.
279   */ 275   */
HITCBC 280   1 tls_context& operator=(tls_context const& other) = default; 276   1 tls_context& operator=(tls_context const& other) = default;
281   277  
282 - /** Move constructor. 278 + /** Transfers ownership of the TLS context from another instance.
283 -  
284 - Transfers ownership of the TLS context from another instance.  
285   After the move, `other` is in a valid but empty state. 279   After the move, `other` is in a valid but empty state.
286   280  
287   @param other The context to move from. 281   @param other The context to move from.
288   */ 282   */
HITCBC 289   2 tls_context(tls_context&& other) noexcept = default; 283   2 tls_context(tls_context&& other) noexcept = default;
290   284  
291 - /** Move assignment operator. 285 + /** Releases the current context's shared ownership and transfers
292 -  
293 - Releases the current context's shared ownership and transfers  
294   ownership from another instance. After the move, `other` is 286   ownership from another instance. After the move, `other` is
295   in a valid but empty state. 287   in a valid but empty state.
296   288  
297   @param other The context to move from. 289   @param other The context to move from.
298   290  
299   @return Reference to this context. 291   @return Reference to this context.
300   */ 292   */
HITCBC 301   1 tls_context& operator=(tls_context&& other) noexcept = default; 293   1 tls_context& operator=(tls_context&& other) noexcept = default;
302   294  
303 - /** Destructor. 295 + /** Releases this handle's shared ownership of the underlying
304 -  
305 - Releases this handle's shared ownership of the underlying  
306   context. The context state is destroyed when the last handle 296   context. The context state is destroyed when the last handle
307   is released. 297   is released.
308   */ 298   */
HITCBC 309   55 ~tls_context() = default; 299   55 ~tls_context() = default;
310   300  
311   // 301   //
312   // Credential Loading 302   // Credential Loading
313   // 303   //
314   304  
315   /** Load the entity certificate from a memory buffer. 305   /** Load the entity certificate from a memory buffer.
316   306  
317   Sets the certificate that identifies this endpoint to the peer. 307   Sets the certificate that identifies this endpoint to the peer.
318   For servers, this is the server certificate. For clients using 308   For servers, this is the server certificate. For clients using
319   mutual TLS, this is the client certificate. 309   mutual TLS, this is the client certificate.
320   310  
321   The certificate must match the private key loaded via 311   The certificate must match the private key loaded via
322   `use_private_key()` or `use_private_key_file()`. 312   `use_private_key()` or `use_private_key_file()`.
323   313  
324   @param certificate The certificate data. 314   @param certificate The certificate data.
325   315  
326   @param format The encoding format of the certificate data. 316   @param format The encoding format of the certificate data.
327   317  
328   @return Success. The certificate is recorded and decoded when the 318   @return Success. The certificate is recorded and decoded when the
329   native context is first built; a malformed certificate surfaces 319   native context is first built; a malformed certificate surfaces
330   as a handshake failure. 320   as a handshake failure.
331   321  
332   @see use_certificate_file 322   @see use_certificate_file
333   @see use_private_key 323   @see use_private_key
334   */ 324   */
335   [[nodiscard]] std::error_code 325   [[nodiscard]] std::error_code
336   use_certificate(std::string_view certificate, tls_file_format format); 326   use_certificate(std::string_view certificate, tls_file_format format);
337   327  
338   /** Load the entity certificate from a file. 328   /** Load the entity certificate from a file.
339   329  
340   Sets the certificate that identifies this endpoint to the peer. 330   Sets the certificate that identifies this endpoint to the peer.
341   For servers, this is the server certificate. For clients using 331   For servers, this is the server certificate. For clients using
342   mutual TLS, this is the client certificate. 332   mutual TLS, this is the client certificate.
343   333  
344   @param filename Path to the certificate file. 334   @param filename Path to the certificate file.
345   335  
346   @param format The encoding format of the file. 336   @param format The encoding format of the file.
347   337  
348   @return Success, or an error if the file could not be read. The 338   @return Success, or an error if the file could not be read. The
349   certificate is decoded when the native context is first built; 339   certificate is decoded when the native context is first built;
350   a malformed certificate surfaces as a handshake failure. 340   a malformed certificate surfaces as a handshake failure.
351   341  
352   @par Example 342   @par Example
353   @par !example use_certificate_file 343   @par !example use_certificate_file
354   344  
355   @see use_certificate 345   @see use_certificate
356   @see use_private_key_file 346   @see use_private_key_file
357   */ 347   */
358   [[nodiscard]] std::error_code 348   [[nodiscard]] std::error_code
359   use_certificate_file(std::string_view filename, tls_file_format format); 349   use_certificate_file(std::string_view filename, tls_file_format format);
360   350  
361   /** Load a certificate chain from a memory buffer. 351   /** Load a certificate chain from a memory buffer.
362   352  
363   Loads the entity certificate followed by intermediate CA certificates. 353   Loads the entity certificate followed by intermediate CA certificates.
364   The chain should be ordered from leaf to root (excluding the root). 354   The chain should be ordered from leaf to root (excluding the root).
365   This is the typical format for PEM certificate bundles. 355   This is the typical format for PEM certificate bundles.
366   356  
367   @param chain The certificate chain data in PEM format (concatenated 357   @param chain The certificate chain data in PEM format (concatenated
368   certificates). 358   certificates).
369   359  
370   @return Success. The chain is recorded and decoded when the native 360   @return Success. The chain is recorded and decoded when the native
371   context is first built; a malformed chain surfaces as a 361   context is first built; a malformed chain surfaces as a
372   handshake failure. 362   handshake failure.
373   363  
374   @see use_certificate_chain_file 364   @see use_certificate_chain_file
375   */ 365   */
376   [[nodiscard]] std::error_code use_certificate_chain(std::string_view chain); 366   [[nodiscard]] std::error_code use_certificate_chain(std::string_view chain);
377   367  
378   /** Load a certificate chain from a file. 368   /** Load a certificate chain from a file.
379   369  
380   Loads the entity certificate followed by intermediate CA certificates 370   Loads the entity certificate followed by intermediate CA certificates
381   from a PEM file. The file should contain concatenated PEM certificates 371   from a PEM file. The file should contain concatenated PEM certificates
382   ordered from leaf to root (excluding the root). 372   ordered from leaf to root (excluding the root).
383   373  
384   @param filename Path to the certificate chain file. 374   @param filename Path to the certificate chain file.
385   375  
386   @return Success, or an error if the file could not be read. The 376   @return Success, or an error if the file could not be read. The
387   chain is decoded when the native context is first built; a 377   chain is decoded when the native context is first built; a
388   malformed chain surfaces as a handshake failure. 378   malformed chain surfaces as a handshake failure.
389   379  
390   @par Example 380   @par Example
391   @par !example use_certificate_chain_file 381   @par !example use_certificate_chain_file
392   382  
393   @see use_certificate_chain 383   @see use_certificate_chain
394   */ 384   */
395   [[nodiscard]] std::error_code 385   [[nodiscard]] std::error_code
396   use_certificate_chain_file(std::string_view filename); 386   use_certificate_chain_file(std::string_view filename);
397   387  
398   /** Load the private key from a memory buffer. 388   /** Load the private key from a memory buffer.
399   389  
400   Sets the private key corresponding to the entity certificate. 390   Sets the private key corresponding to the entity certificate.
401   The key must match the certificate loaded via `use_certificate()` 391   The key must match the certificate loaded via `use_certificate()`
402   or `use_certificate_chain()`. 392   or `use_certificate_chain()`.
403   393  
404   If the key is encrypted, set a password callback via 394   If the key is encrypted, set a password callback via
405   `set_password_callback()` before calling this function. 395   `set_password_callback()` before calling this function.
406   396  
407   @param private_key The private key data. 397   @param private_key The private key data.
408   398  
409   @param format The encoding format of the key data. 399   @param format The encoding format of the key data.
410   400  
411   @return Success. The key is recorded and decoded when the native 401   @return Success. The key is recorded and decoded when the native
412 - context is first built; a malformed key, a missing password 402 + context is first built. Three faults surface only as a handshake
413 - callback for an encrypted key, or a certificate mismatch 403 + failure: a malformed key, a missing password callback for an
414 - surfaces as a handshake failure. 404 + encrypted key, and a certificate mismatch.
415   405  
416   @see use_private_key_file 406   @see use_private_key_file
417   @see set_password_callback 407   @see set_password_callback
418   */ 408   */
419   [[nodiscard]] std::error_code 409   [[nodiscard]] std::error_code
420   use_private_key(std::string_view private_key, tls_file_format format); 410   use_private_key(std::string_view private_key, tls_file_format format);
421   411  
422   /** Load the private key from a file. 412   /** Load the private key from a file.
423   413  
424   Sets the private key corresponding to the entity certificate. 414   Sets the private key corresponding to the entity certificate.
425   The key must match the certificate loaded via `use_certificate_file()` 415   The key must match the certificate loaded via `use_certificate_file()`
426   or `use_certificate_chain_file()`. 416   or `use_certificate_chain_file()`.
427   417  
428   If the key file is encrypted, set a password callback via 418   If the key file is encrypted, set a password callback via
429   `set_password_callback()` before calling this function. 419   `set_password_callback()` before calling this function.
430   420  
431   @param filename Path to the private key file. 421   @param filename Path to the private key file.
432   422  
433   @param format The encoding format of the file. 423   @param format The encoding format of the file.
434   424  
435   @return Success, or an error if the file could not be read. The 425   @return Success, or an error if the file could not be read. The
436   key is decoded when the native context is first built; a 426   key is decoded when the native context is first built; a
437   malformed key or a certificate mismatch surfaces as a 427   malformed key or a certificate mismatch surfaces as a
438   handshake failure. 428   handshake failure.
439   429  
440   @par Example 430   @par Example
441   @par !example use_private_key_file 431   @par !example use_private_key_file
442   432  
443   @see use_private_key 433   @see use_private_key
444   @see set_password_callback 434   @see set_password_callback
445   */ 435   */
446   [[nodiscard]] std::error_code 436   [[nodiscard]] std::error_code
447   use_private_key_file(std::string_view filename, tls_file_format format); 437   use_private_key_file(std::string_view filename, tls_file_format format);
448   438  
449   /** Load credentials from a PKCS#12 bundle in memory. 439   /** Load credentials from a PKCS#12 bundle in memory.
450   440  
451   PKCS#12 (also known as PFX) is a binary format that bundles a 441   PKCS#12 (also known as PFX) is a binary format that bundles a
452   certificate, private key, and optionally intermediate certificates 442   certificate, private key, and optionally intermediate certificates
453   into a single password-protected file. 443   into a single password-protected file.
454   444  
455   @param data The PKCS#12 bundle data. 445   @param data The PKCS#12 bundle data.
456   446  
457   @param passphrase The password protecting the bundle. 447   @param passphrase The password protecting the bundle.
458   448  
459   @return Success. The bundle is recorded and decoded into the 449   @return Success. The bundle is recorded and decoded into the
460 - certificate, private key, and chain when the native context is 450 + certificate, private key, and chain when the native context is
461 - first built; a malformed bundle or wrong passphrase surfaces as 451 + first built. A malformed bundle or a wrong passphrase surfaces as a
462 - a handshake failure. 452 + handshake failure.
463   453  
464   @note Intermediate certificates inside the bundle are loaded and 454   @note Intermediate certificates inside the bundle are loaded and
465   sent during the handshake on both backends. 455   sent during the handshake on both backends.
466   456  
467   @see use_pkcs12_file 457   @see use_pkcs12_file
468   */ 458   */
469   [[nodiscard]] std::error_code 459   [[nodiscard]] std::error_code
470   use_pkcs12(std::string_view data, std::string_view passphrase); 460   use_pkcs12(std::string_view data, std::string_view passphrase);
471   461  
472   /** Load credentials from a PKCS#12 file. 462   /** Load credentials from a PKCS#12 file.
473   463  
474   PKCS#12 (also known as PFX) is a binary format that bundles a 464   PKCS#12 (also known as PFX) is a binary format that bundles a
475   certificate, private key, and optionally intermediate certificates 465   certificate, private key, and optionally intermediate certificates
476   into a single password-protected file. This is common on Windows 466   into a single password-protected file. This is common on Windows
477   and for certificates exported from browsers. 467   and for certificates exported from browsers.
478   468  
479   @param filename Path to the PKCS#12 file. 469   @param filename Path to the PKCS#12 file.
480   470  
481   @param passphrase The password protecting the file. 471   @param passphrase The password protecting the file.
482   472  
483   @return Success, or an error if the file could not be read. The 473   @return Success, or an error if the file could not be read. The
484   bundle is decoded when the native context is first built; a 474   bundle is decoded when the native context is first built; a
485   malformed bundle or wrong passphrase surfaces as a handshake 475   malformed bundle or wrong passphrase surfaces as a handshake
486   failure. 476   failure.
487   477  
488   @note Intermediate certificates inside the bundle are loaded and 478   @note Intermediate certificates inside the bundle are loaded and
489   sent during the handshake on both backends. 479   sent during the handshake on both backends.
490   480  
491   @par Example 481   @par Example
492   @par !example use_pkcs12_file 482   @par !example use_pkcs12_file
493   483  
494   @see use_pkcs12 484   @see use_pkcs12
495   */ 485   */
496   [[nodiscard]] std::error_code 486   [[nodiscard]] std::error_code
497   use_pkcs12_file(std::string_view filename, std::string_view passphrase); 487   use_pkcs12_file(std::string_view filename, std::string_view passphrase);
498   488  
499   // 489   //
500   // Trust Anchors 490   // Trust Anchors
501   // 491   //
502   492  
503   /** Add a certificate authority for peer verification. 493   /** Add a certificate authority for peer verification.
504   494  
505   Adds a single CA certificate to the trust store used for verifying 495   Adds a single CA certificate to the trust store used for verifying
506   peer certificates. Call this multiple times to add multiple CAs, 496   peer certificates. Call this multiple times to add multiple CAs,
507   or use `load_verify_file()` for a bundle. 497   or use `load_verify_file()` for a bundle.
508   498  
509   @param ca The CA certificate data in PEM format. 499   @param ca The CA certificate data in PEM format.
510   500  
511   @return Success. The certificate is recorded and decoded when the 501   @return Success. The certificate is recorded and decoded when the
512   native context is first built; a malformed certificate 502   native context is first built; a malformed certificate
513   surfaces as a handshake failure. 503   surfaces as a handshake failure.
514   504  
515   @see load_verify_file 505   @see load_verify_file
516   @see set_default_verify_paths 506   @see set_default_verify_paths
517   */ 507   */
518   [[nodiscard]] std::error_code 508   [[nodiscard]] std::error_code
519   add_certificate_authority(std::string_view ca); 509   add_certificate_authority(std::string_view ca);
520   510  
521   /** Load CA certificates from a file. 511   /** Load CA certificates from a file.
522   512  
523   Loads one or more CA certificates from a PEM file. The file may 513   Loads one or more CA certificates from a PEM file. The file may
524   contain multiple concatenated PEM certificates. 514   contain multiple concatenated PEM certificates.
525   515  
526   @param filename Path to a PEM file containing CA certificates. 516   @param filename Path to a PEM file containing CA certificates.
527   517  
528   @return Success, or an error if the file could not be read. The 518   @return Success, or an error if the file could not be read. The
529   certificates are decoded when the native context is first 519   certificates are decoded when the native context is first
530   built; malformed certificates surface as a handshake failure. 520   built; malformed certificates surface as a handshake failure.
531   521  
532   @par Example 522   @par Example
533   @par !example load_verify_file 523   @par !example load_verify_file
534   524  
535   @see add_certificate_authority 525   @see add_certificate_authority
536   @see add_verify_path 526   @see add_verify_path
537   */ 527   */
538   [[nodiscard]] std::error_code load_verify_file(std::string_view filename); 528   [[nodiscard]] std::error_code load_verify_file(std::string_view filename);
539   529  
540   /** Add a directory of CA certificates for verification. 530   /** Add a directory of CA certificates for verification.
541   531  
542   Adds a directory of CA certificates to the trust store. The 532   Adds a directory of CA certificates to the trust store. The
543   directory is applied when the native context is first built from 533   directory is applied when the native context is first built from
544   this context. 534   this context.
545   535  
546   The expected directory layout depends on the backend. OpenSSL 536   The expected directory layout depends on the backend. OpenSSL
547 - performs on-demand lookups and requires each certificate file to 537 + performs on-demand lookups. Each certificate file must be named
548 - be named by its subject-name hash (as generated by 538 + by its subject-name hash, as generated by `openssl rehash` or
549 - `openssl rehash` or `c_rehash`); WolfSSL loads every certificate 539 + `c_rehash`. WolfSSL loads every certificate file in the
550 - file in the directory. 540 + directory.
551   541  
552   @param path Path to the directory of CA certificates. 542   @param path Path to the directory of CA certificates.
553   543  
554   @return Success. The path is recorded and applied when the native 544   @return Success. The path is recorded and applied when the native
555 - context is built; a directory that cannot be read at that time 545 + context is built. A directory that cannot be read at that time is
556 - is skipped rather than reported here. 546 + skipped rather than reported here.
557   547  
558   @par Example 548   @par Example
559   @par !example add_verify_path 549   @par !example add_verify_path
560   550  
561   @see load_verify_file 551   @see load_verify_file
562   @see set_default_verify_paths 552   @see set_default_verify_paths
563   */ 553   */
564   [[nodiscard]] std::error_code add_verify_path(std::string_view path); 554   [[nodiscard]] std::error_code add_verify_path(std::string_view path);
565   555  
566   /** Use the system default CA certificate store. 556   /** Use the system default CA certificate store.
567   557  
568   Configures the context to use the operating system's default 558   Configures the context to use the operating system's default
569   trust store for peer certificate verification. This is the 559   trust store for peer certificate verification. This is the
570   recommended approach for HTTPS clients connecting to public 560   recommended approach for HTTPS clients connecting to public
571   servers. 561   servers.
572   562  
573   The system store is loaded when the native context is first built 563   The system store is loaded when the native context is first built
574   from this context. For a verified-safe client, combine this with 564   from this context. For a verified-safe client, combine this with
575   `set_verify_mode( tls_verify_mode::peer )` and, when connecting by 565   `set_verify_mode( tls_verify_mode::peer )` and, when connecting by
576   name, `tls_stream::set_hostname()`. 566   name, `tls_stream::set_hostname()`.
577   567  
578   @return Success. The request is recorded and applied when the 568   @return Success. The request is recorded and applied when the
579 - native context is built; if the system store cannot be loaded 569 + native context is built. A system store that cannot be loaded at
580 - at that time it is skipped rather than reported here, so a 570 + that time is skipped rather than reported here. A context that
581 - context that must reject unverified peers should also use 571 + must reject unverified peers should therefore also use
582 - `set_verify_mode( tls_verify_mode::peer )`. 572 + `set_verify_mode( tls_verify_mode::peer )`.
583   573  
584   @note The OpenSSL backend honors the `SSL_CERT_FILE` and 574   @note The OpenSSL backend honors the `SSL_CERT_FILE` and
585   `SSL_CERT_DIR` environment variables. The WolfSSL backend 575   `SSL_CERT_DIR` environment variables. The WolfSSL backend
586   requires a build with `WOLFSSL_SYS_CA_CERTS`; without it the 576   requires a build with `WOLFSSL_SYS_CA_CERTS`; without it the
587   system store is unavailable and this call has no effect. 577   system store is unavailable and this call has no effect.
588   578  
589   @par Example 579   @par Example
590   @par !example set_default_verify_paths 580   @par !example set_default_verify_paths
591   581  
592   @see load_verify_file 582   @see load_verify_file
593   @see add_verify_path 583   @see add_verify_path
594   @see set_verify_mode 584   @see set_verify_mode
595   */ 585   */
596   [[nodiscard]] std::error_code set_default_verify_paths(); 586   [[nodiscard]] std::error_code set_default_verify_paths();
597   587  
598   // 588   //
599   // Protocol Configuration 589   // Protocol Configuration
600   // 590   //
601   591  
602   /** Set the minimum TLS protocol version. 592   /** Set the minimum TLS protocol version.
603   593  
604 - Connections will reject protocol versions older than this. 594 + Connections reject protocol versions older than this.
605   The default allows TLS 1.2 and newer. 595   The default allows TLS 1.2 and newer.
606   596  
607   @param v The minimum protocol version to accept. 597   @param v The minimum protocol version to accept.
608   598  
609   @return Success. The version is recorded and applied when the 599   @return Success. The version is recorded and applied when the
610   native context is first built. 600   native context is first built.
611   601  
612   @par Example 602   @par Example
613   @par !example set_min_protocol_version 603   @par !example set_min_protocol_version
614   604  
615   @see set_max_protocol_version 605   @see set_max_protocol_version
616   */ 606   */
617   [[nodiscard]] std::error_code set_min_protocol_version(tls_version v); 607   [[nodiscard]] std::error_code set_min_protocol_version(tls_version v);
618   608  
619   /** Set the maximum TLS protocol version. 609   /** Set the maximum TLS protocol version.
620   610  
621 - Connections will not negotiate protocol versions newer than this. 611 + Connections do not negotiate protocol versions newer than this.
622   The default allows the newest supported version. 612   The default allows the newest supported version.
623   613  
624   @param v The maximum protocol version to accept. 614   @param v The maximum protocol version to accept.
625   615  
626   @return Success. The version is recorded and applied when the 616   @return Success. The version is recorded and applied when the
627   native context is first built. 617   native context is first built.
628   618  
629   @note On WolfSSL the ceiling is applied by selecting a 619   @note On WolfSSL the ceiling is applied by selecting a
630 - version-specific method (no native set-max API exists); an 620 + version-specific method, because no native set-max API exists. An
631 - invalid window where the minimum exceeds the maximum yields a 621 + invalid window, where the minimum exceeds the maximum, yields a
632 - context that fails the handshake. 622 + context that fails the handshake.
633   623  
634   @see set_min_protocol_version 624   @see set_min_protocol_version
635   */ 625   */
636   [[nodiscard]] std::error_code set_max_protocol_version(tls_version v); 626   [[nodiscard]] std::error_code set_max_protocol_version(tls_version v);
637   627  
638   /** Set the allowed cipher suites. 628   /** Set the allowed cipher suites.
639   629  
640   Configures which cipher suites may be used for connections. 630   Configures which cipher suites may be used for connections.
641   The format is backend-specific but typically follows OpenSSL 631   The format is backend-specific but typically follows OpenSSL
642   cipher list syntax. 632   cipher list syntax.
643   633  
644   @param ciphers The cipher suite specification string. 634   @param ciphers The cipher suite specification string.
645   635  
646   @return Success. The string is recorded and applied when the 636   @return Success. The string is recorded and applied when the
647   native context is first built; an invalid cipher string 637   native context is first built; an invalid cipher string
648   surfaces as a handshake failure. 638   surfaces as a handshake failure.
649   639  
650   @par Example 640   @par Example
651   @par !example set_ciphersuites 641   @par !example set_ciphersuites
652   642  
653   @note This configures cipher suites for TLS 1.2 and below. For 643   @note This configures cipher suites for TLS 1.2 and below. For
654   TLS 1.3, use @ref set_ciphersuites_tls13. 644   TLS 1.3, use @ref set_ciphersuites_tls13.
655   */ 645   */
656   [[nodiscard]] std::error_code set_ciphersuites(std::string_view ciphers); 646   [[nodiscard]] std::error_code set_ciphersuites(std::string_view ciphers);
657   647  
658   /** Set the allowed TLS 1.3 cipher suites. 648   /** Set the allowed TLS 1.3 cipher suites.
659   649  
660   TLS 1.3 uses a distinct, fixed set of cipher suites configured 650   TLS 1.3 uses a distinct, fixed set of cipher suites configured
661   separately from earlier versions. The format is a colon-separated 651   separately from earlier versions. The format is a colon-separated
662   list of TLS 1.3 suite names. 652   list of TLS 1.3 suite names.
663   653  
664   @param ciphers The TLS 1.3 cipher suite list. 654   @param ciphers The TLS 1.3 cipher suite list.
665   655  
666   @return Success. The string is recorded and applied when the 656   @return Success. The string is recorded and applied when the
667   native context is first built; an invalid cipher string 657   native context is first built; an invalid cipher string
668   surfaces as a handshake failure. 658   surfaces as a handshake failure.
669   659  
670   @par Example 660   @par Example
671   @par !example set_ciphersuites_tls13 661   @par !example set_ciphersuites_tls13
672   662  
673   @note On the WolfSSL backend, TLS 1.2 and TLS 1.3 suites share a 663   @note On the WolfSSL backend, TLS 1.2 and TLS 1.3 suites share a
674   single cipher list; this call and @ref set_ciphersuites are 664   single cipher list; this call and @ref set_ciphersuites are
675   merged into one list. 665   merged into one list.
676   666  
677   @see set_ciphersuites 667   @see set_ciphersuites
678   */ 668   */
679   [[nodiscard]] std::error_code 669   [[nodiscard]] std::error_code
680   set_ciphersuites_tls13(std::string_view ciphers); 670   set_ciphersuites_tls13(std::string_view ciphers);
681   671  
682   /** Set the ALPN protocol list. 672   /** Set the ALPN protocol list.
683   673  
684   Configures Application-Layer Protocol Negotiation (ALPN) for 674   Configures Application-Layer Protocol Negotiation (ALPN) for
685   the connection. ALPN is used to negotiate which application 675   the connection. ALPN is used to negotiate which application
686   protocol to use over the TLS connection (e.g., "h2" for HTTP/2, 676   protocol to use over the TLS connection (e.g., "h2" for HTTP/2,
687   "http/1.1" for HTTP/1.1). 677   "http/1.1" for HTTP/1.1).
688   678  
689   The protocols are tried in preference order (first = highest). 679   The protocols are tried in preference order (first = highest).
690   680  
691   @param protocols Ordered list of protocol identifiers. 681   @param protocols Ordered list of protocol identifiers.
692   682  
693   @return Success, or an error if ALPN configuration fails. 683   @return Success, or an error if ALPN configuration fails.
694   684  
695   @note Read the negotiated protocol after the handshake via 685   @note Read the negotiated protocol after the handshake via
696   @ref tls_stream::alpn_protocol. On WolfSSL, ALPN requires a 686   @ref tls_stream::alpn_protocol. On WolfSSL, ALPN requires a
697   build with `HAVE_ALPN`; without it, offering protocols fails 687   build with `HAVE_ALPN`; without it, offering protocols fails
698   the handshake with `std::errc::function_not_supported` rather 688   the handshake with `std::errc::function_not_supported` rather
699   than negotiate nothing silently. 689   than negotiate nothing silently.
700   690  
701   @par Example 691   @par Example
702   @par !example set_alpn 692   @par !example set_alpn
703   */ 693   */
704   [[nodiscard]] std::error_code 694   [[nodiscard]] std::error_code
705   set_alpn(std::initializer_list<std::string_view> protocols); 695   set_alpn(std::initializer_list<std::string_view> protocols);
706   696  
707   // 697   //
708   // Certificate Verification 698   // Certificate Verification
709   // 699   //
710   700  
711   /** Set the peer certificate verification mode. 701   /** Set the peer certificate verification mode.
712   702  
713   Controls whether and how peer certificates are verified during 703   Controls whether and how peer certificates are verified during
714   the TLS handshake. 704   the TLS handshake.
715   705  
716   @param mode The verification mode to use. 706   @param mode The verification mode to use.
717   707  
718   @return Success. The mode is recorded and applied when the native 708   @return Success. The mode is recorded and applied when the native
719   context is first built. 709   context is first built.
720   710  
721   @par Example 711   @par Example
722   @par !example set_verify_mode 712   @par !example set_verify_mode
723   713  
724   @see tls_verify_mode 714   @see tls_verify_mode
725   */ 715   */
726   [[nodiscard]] std::error_code set_verify_mode(tls_verify_mode mode); 716   [[nodiscard]] std::error_code set_verify_mode(tls_verify_mode mode);
727   717  
728   /** Set the maximum certificate chain verification depth. 718   /** Set the maximum certificate chain verification depth.
729   719  
730   Limits how many intermediate certificates can appear between 720   Limits how many intermediate certificates can appear between
731   the peer certificate and a trusted root. The default is 721   the peer certificate and a trusted root. The default is
732   typically 100, which is sufficient for most certificate chains. 722   typically 100, which is sufficient for most certificate chains.
733   723  
734   @param depth Maximum number of intermediate certificates allowed. 724   @param depth Maximum number of intermediate certificates allowed.
735   725  
736   @return Success. The depth is recorded and applied when the native 726   @return Success. The depth is recorded and applied when the native
737   context is first built. 727   context is first built.
  728 +
  729 + @par Example
  730 + @par !example set_verify_depth
738   */ 731   */
739   [[nodiscard]] std::error_code set_verify_depth(int depth); 732   [[nodiscard]] std::error_code set_verify_depth(int depth);
740   733  
741   /** Set a custom certificate verification callback. 734   /** Set a custom certificate verification callback.
742   735  
743   Installs a callback that is invoked during certificate chain 736   Installs a callback that is invoked during certificate chain
744   verification. The callback can perform additional validation 737   verification. The callback can perform additional validation
745   beyond the standard checks and can override verification 738   beyond the standard checks and can override verification
746   results. 739   results.
747   740  
748   The callback receives the built-in verification result so far and 741   The callback receives the built-in verification result so far and
749 - a verify_context describing the certificate being verified. Return 742 + a `verify_context` describing the certificate being verified. Return
750   `true` to accept the certificate, `false` to reject. Inspect the 743   `true` to accept the certificate, `false` to reject. Inspect the
751   certificate portably via `verify_context::certificate()` (its DER 744   certificate portably via `verify_context::certificate()` (its DER
752   encoding) — for example to pin a specific certificate. 745   encoding) — for example to pin a specific certificate.
753   746  
754   @par Backend Support 747   @par Backend Support
755   748  
756   The exact set of certificates the callback sees differs by backend: 749   The exact set of certificates the callback sees differs by backend:
757   750  
758   - OpenSSL: the callback runs once per certificate in the chain, 751   - OpenSSL: the callback runs once per certificate in the chain,
759   including certificates that passed the built-in checks. It can 752   including certificates that passed the built-in checks. It can
760 - therefore both relax verification (return `true` for a 753 + therefore relax verification by returning `true` for a
761 - certificate the library rejected) and tighten it (return `false` 754 + certificate the library rejected. It can also tighten
762 - for a certificate the library accepted, e.g. pinning). 755 + verification by returning `false` for a certificate the library
  756 + accepted, as pinning does.
763   - WolfSSL built with `WOLFSSL_ALWAYS_VERIFY_CB` (implied by 757   - WolfSSL built with `WOLFSSL_ALWAYS_VERIFY_CB` (implied by
764   `--enable-opensslextra`): same as OpenSSL. 758   `--enable-opensslextra`): same as OpenSSL.
765   - WolfSSL without that option: the library invokes the callback 759   - WolfSSL without that option: the library invokes the callback
766   only on verification *failure*, so it cannot be honored on a 760   only on verification *failure*, so it cannot be honored on a
767 - successful handshake. To avoid silently ignoring a 761 + successful handshake. Silently ignoring a verification-tightening
768 - verification-tightening callback (which would fail open), a 762 + callback would fail open. On such a build, a context that carries
769 - context that carries a callback instead **fails the handshake** 763 + a callback instead **fails the handshake** with
770 - with `std::errc::function_not_supported` on such a build. Rebuild 764 + `std::errc::function_not_supported`. Rebuild
771   WolfSSL with `WOLFSSL_ALWAYS_VERIFY_CB`, or omit the callback. 765   WolfSSL with `WOLFSSL_ALWAYS_VERIFY_CB`, or omit the callback.
772   766  
773   @tparam Callback A callable with signature 767   @tparam Callback A callable with signature
774   `bool( bool preverified, verify_context& ctx )`. 768   `bool( bool preverified, verify_context& ctx )`.
775   769  
776   @param callback The verification callback. Recorded here and 770   @param callback The verification callback. Recorded here and
777   applied during the handshake; on a WolfSSL build that 771   applied during the handshake; on a WolfSSL build that
778   cannot honor it, the handshake fails with 772   cannot honor it, the handshake fails with
779   `std::errc::function_not_supported` (see Backend Support). 773   `std::errc::function_not_supported` (see Backend Support).
780   774  
781   @par Example 775   @par Example
782   @par !example set_verify_callback 776   @par !example set_verify_callback
783   777  
784   @see verify_context 778   @see verify_context
785   @see set_verify_mode 779   @see set_verify_mode
786   */ 780   */
787   template<typename Callback> 781   template<typename Callback>
788   void set_verify_callback(Callback callback); 782   void set_verify_callback(Callback callback);
789   783  
790   /** Set a callback for Server Name Indication (SNI). 784   /** Set a callback for Server Name Indication (SNI).
791   785  
792   For server connections, this callback is invoked during the TLS 786   For server connections, this callback is invoked during the TLS
793   handshake when a client sends an SNI extension. The callback 787   handshake when a client sends an SNI extension. The callback
794   receives the requested hostname and can accept or reject the 788   receives the requested hostname and can accept or reject the
795   connection. 789   connection.
796   790  
797   @tparam Callback A callable with signature 791   @tparam Callback A callable with signature
798   `bool( std::string_view hostname )`. 792   `bool( std::string_view hostname )`.
799   793  
800   @param callback The SNI callback. Return `true` to accept the 794   @param callback The SNI callback. Return `true` to accept the
801   connection or `false` to reject it with an alert. 795   connection or `false` to reject it with an alert.
802   796  
803   @par Example 797   @par Example
804   @par !example set_servername_callback 798   @par !example set_servername_callback
805   799  
806   @note For virtual hosting with different certificates per hostname, 800   @note For virtual hosting with different certificates per hostname,
807   create separate contexts and select the appropriate one before 801   create separate contexts and select the appropriate one before
808   creating the TLS stream. 802   creating the TLS stream.
809   803  
810   @see tls_stream::set_hostname 804   @see tls_stream::set_hostname
811   */ 805   */
812   template<typename Callback> 806   template<typename Callback>
813   void set_servername_callback(Callback callback); 807   void set_servername_callback(Callback callback);
814   808  
815   private: 809   private:
816   void set_servername_callback_impl( 810   void set_servername_callback_impl(
817   std::function<bool(std::string_view)> callback); 811   std::function<bool(std::string_view)> callback);
818   812  
819   void set_password_callback_impl( 813   void set_password_callback_impl(
820   std::function<std::string(std::size_t, tls_password_purpose)> callback); 814   std::function<std::string(std::size_t, tls_password_purpose)> callback);
821   815  
822   void set_verify_callback_impl( 816   void set_verify_callback_impl(
823   std::function<bool(bool, verify_context&)> callback); 817   std::function<bool(bool, verify_context&)> callback);
824   818  
825   public: 819   public:
826   // 820   //
827   // Revocation Checking 821   // Revocation Checking
828   // 822   //
829   823  
830   /** Add a Certificate Revocation List from memory. 824   /** Add a Certificate Revocation List from memory.
831   825  
832   Adds a CRL to the verification store for checking whether 826   Adds a CRL to the verification store for checking whether
833 - certificates have been revoked. CRLs are typically fetched 827 + certificates are revoked. CRLs are typically fetched
834   from the URLs in a certificate's CRL Distribution Points 828   from the URLs in a certificate's CRL Distribution Points
835   extension. 829   extension.
836   830  
837   @param crl The CRL data in DER or PEM format. 831   @param crl The CRL data in DER or PEM format.
838   832  
839   @return Success. The CRL is recorded and decoded when the native 833   @return Success. The CRL is recorded and decoded when the native
840   context is first built; a malformed CRL surfaces as a 834   context is first built; a malformed CRL surfaces as a
841   handshake failure. 835   handshake failure.
842   836  
843   @note CRLs are consulted only when a revocation policy is set via 837   @note CRLs are consulted only when a revocation policy is set via
844   @ref set_revocation_policy. On WolfSSL, CRL checking requires a 838   @ref set_revocation_policy. On WolfSSL, CRL checking requires a
845   build with `HAVE_CRL`; without it, supplying a CRL or a 839   build with `HAVE_CRL`; without it, supplying a CRL or a
846   revocation policy fails the handshake with 840   revocation policy fails the handshake with
847   `std::errc::function_not_supported`. 841   `std::errc::function_not_supported`.
848   842  
849   @see add_crl_file 843   @see add_crl_file
850   @see set_revocation_policy 844   @see set_revocation_policy
851   */ 845   */
852   [[nodiscard]] std::error_code add_crl(std::string_view crl); 846   [[nodiscard]] std::error_code add_crl(std::string_view crl);
853   847  
854   /** Add a Certificate Revocation List from a file. 848   /** Add a Certificate Revocation List from a file.
855   849  
856   Adds a CRL to the verification store for checking whether 850   Adds a CRL to the verification store for checking whether
857 - certificates have been revoked. 851 + certificates are revoked.
858   852  
859   @param filename Path to a CRL file (DER or PEM format). 853   @param filename Path to a CRL file (DER or PEM format).
860   854  
861   @return Success, or an error if the file could not be read. The 855   @return Success, or an error if the file could not be read. The
862   CRL is decoded when the native context is first built; a 856   CRL is decoded when the native context is first built; a
863   malformed CRL surfaces as a handshake failure. 857   malformed CRL surfaces as a handshake failure.
864   858  
865   @note CRLs are consulted only when a revocation policy is set via 859   @note CRLs are consulted only when a revocation policy is set via
866   @ref set_revocation_policy (WolfSSL requires a `HAVE_CRL` 860   @ref set_revocation_policy (WolfSSL requires a `HAVE_CRL`
867   build). 861   build).
868   862  
869   @par Example 863   @par Example
870   @par !example add_crl_file 864   @par !example add_crl_file
871   865  
872   @see add_crl 866   @see add_crl
873   @see set_revocation_policy 867   @see set_revocation_policy
874   */ 868   */
875   [[nodiscard]] std::error_code add_crl_file(std::string_view filename); 869   [[nodiscard]] std::error_code add_crl_file(std::string_view filename);
876   870  
877   /** Set the certificate revocation checking policy. 871   /** Set the certificate revocation checking policy.
878   872  
879   Controls how certificate revocation status is checked during 873   Controls how certificate revocation status is checked during
880   verification via CRLs. 874   verification via CRLs.
881   875  
882   @param policy The revocation checking policy. 876   @param policy The revocation checking policy.
883   877  
884   @par Example 878   @par Example
885   @par !example set_revocation_policy 879   @par !example set_revocation_policy
886   880  
887   @note Revocation is checked via CRLs supplied with @ref add_crl / 881   @note Revocation is checked via CRLs supplied with @ref add_crl /
888   @ref add_crl_file. `soft_fail` accepts a certificate whose 882   @ref add_crl_file. `soft_fail` accepts a certificate whose
889   status cannot be determined (missing/expired CRL) but rejects 883   status cannot be determined (missing/expired CRL) but rejects
890   one that is actually revoked; `hard_fail` also rejects unknown 884   one that is actually revoked; `hard_fail` also rejects unknown
891   status. OCSP-based revocation is not available (see the TLS 885   status. OCSP-based revocation is not available (see the TLS
892   guide). On WolfSSL a non-disabled policy requires a `HAVE_CRL` 886   guide). On WolfSSL a non-disabled policy requires a `HAVE_CRL`
893   build, else the handshake fails with 887   build, else the handshake fails with
894   `std::errc::function_not_supported`. 888   `std::errc::function_not_supported`.
895   889  
896   @see tls_revocation_policy 890   @see tls_revocation_policy
897   @see add_crl 891   @see add_crl
898   */ 892   */
899   void set_revocation_policy(tls_revocation_policy policy); 893   void set_revocation_policy(tls_revocation_policy policy);
900   894  
901   // 895   //
902   // Password Handling 896   // Password Handling
903   // 897   //
904   898  
905   /** Set the password callback for encrypted keys. 899   /** Set the password callback for encrypted keys.
906   900  
907   Installs a callback that provides passwords for encrypted 901   Installs a callback that provides passwords for encrypted
908   private keys and PKCS#12 files. The callback is invoked when 902   private keys and PKCS#12 files. The callback is invoked when
909   loading encrypted key material. 903   loading encrypted key material.
910   904  
911   @tparam Callback A callable with signature 905   @tparam Callback A callable with signature
912 - `std::string( std::size_t max_length, password_purpose purpose )`. 906 + `std::string( std::size_t max_length, tls_password_purpose purpose )`.
913   907  
914   @param callback The password callback. It receives the maximum 908   @param callback The password callback. It receives the maximum
915   password length and the purpose (reading or writing), and 909   password length and the purpose (reading or writing), and
916   returns the password string. 910   returns the password string.
917   911  
918   @par Example 912   @par Example
919   @par !example set_password_callback 913   @par !example set_password_callback
920   914  
921   @see tls_password_purpose 915   @see tls_password_purpose
922   */ 916   */
923   template<typename Callback> 917   template<typename Callback>
924   void set_password_callback(Callback callback); 918   void set_password_callback(Callback callback);
925   }; 919   };
926   #ifdef _MSC_VER 920   #ifdef _MSC_VER
927   #pragma warning(pop) 921   #pragma warning(pop)
928   #endif 922   #endif
929   923  
930   template<typename Callback> 924   template<typename Callback>
931   void 925   void
HITCBC 932   1 tls_context::set_servername_callback(Callback callback) 926   1 tls_context::set_servername_callback(Callback callback)
933   { 927   {
HITCBC 934   1 set_servername_callback_impl(std::move(callback)); 928   1 set_servername_callback_impl(std::move(callback));
HITCBC 935   1 } 929   1 }
936   930  
937   template<typename Callback> 931   template<typename Callback>
938   void 932   void
HITCBC 939   4 tls_context::set_password_callback(Callback callback) 933   4 tls_context::set_password_callback(Callback callback)
940   { 934   {
HITCBC 941   4 set_password_callback_impl(std::move(callback)); 935   4 set_password_callback_impl(std::move(callback));
HITCBC 942   4 } 936   4 }
943   937  
944   template<typename Callback> 938   template<typename Callback>
945   void 939   void
HITCBC 946   2 tls_context::set_verify_callback(Callback callback) 940   2 tls_context::set_verify_callback(Callback callback)
947   { 941   {
HITCBC 948   2 set_verify_callback_impl(std::move(callback)); 942   2 set_verify_callback_impl(std::move(callback));
HITCBC 949   2 } 943   2 }
950   944  
951   } // namespace boost::corosio 945   } // namespace boost::corosio
952   946  
953   #endif 947   #endif