. /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   /** Exposes the certificate and error state to a verification callback. 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   /** Configures the certificates, keys, and protocol settings a TLS stream uses. 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 the
214 - backend implementations, among them OpenSSL, WolfSSL, mbedTLS and 214 + OpenSSL and WolfSSL backends. Portable code therefore works
215 - Schannel. Portable code therefore works regardless of which TLS 215 + regardless of which TLS library is linked.
216 - library is linked.  
217   216  
218   @par Modification After Stream Creation 217   @par Modification After Stream Creation
219   218  
220   Modifying a context after creating a TLS stream from it 219   Modifying a context after creating a TLS stream from it
221 - results in undefined behavior. The context's configuration is 220 + results in undefined behavior. Most settings are captured at the
222 - captured when the first stream is constructed, and subsequent 221 + first handshake of any stream using it; others, such as callbacks,
223 - modifications are not reflected in existing or new streams 222 + are read later. A modification may therefore apply partly or not at
224 - sharing the context. 223 + all.
225   224  
226   If different configurations are needed, create separate context 225   If different configurations are needed, create separate context
227   objects. 226   objects.
228   227  
229   @par Thread Safety 228   @par Thread Safety
230   229  
231   Distinct objects: Safe. 230   Distinct objects: Safe.
232   231  
233   Shared objects: Unsafe. A context must not be modified while 232   Shared objects: Unsafe. A context must not be modified while
234   any thread is creating streams from it. 233   any thread is creating streams from it.
235   234  
236   @par Example 235   @par Example
237   @par !example tls_context 236   @par !example tls_context
238   237  
239   @see tls_role 238   @see tls_role
240   */ 239   */
241   class BOOST_COROSIO_DECL tls_context 240   class BOOST_COROSIO_DECL tls_context
242   { 241   {
243   struct implementation; 242   struct implementation;
244   std::shared_ptr<implementation> impl_; 243   std::shared_ptr<implementation> impl_;
245   244  
246   friend detail::tls_context_data const& 245   friend detail::tls_context_data const&
247   detail::get_tls_context_data(tls_context const&) noexcept; 246   detail::get_tls_context_data(tls_context const&) noexcept;
248   247  
249   public: 248   public:
250   /** Construct a default TLS context. 249   /** Construct a default TLS context.
251   250  
252   Creates a context with default settings suitable for TLS 1.2 251   Creates a context with default settings suitable for TLS 1.2
253   and TLS 1.3 connections. No certificates or trust anchors are 252   and TLS 1.3 connections. No certificates or trust anchors are
254   loaded; call the appropriate methods to configure credentials 253   loaded; call the appropriate methods to configure credentials
255   and verification. 254   and verification.
256   255  
257   @par Example 256   @par Example
258   @par !example tls_context 257   @par !example tls_context
259   */ 258   */
260   tls_context(); 259   tls_context();
261   260  
262   /** Creates a new handle that shares ownership of the underlying 261   /** Creates a new handle that shares ownership of the underlying
263   TLS context state with `other`. 262   TLS context state with `other`.
264   263  
265   @param other The context to copy from. 264   @param other The context to copy from.
266   */ 265   */
HITCBC 267   2 tls_context(tls_context const& other) = default; 266   2 tls_context(tls_context const& other) = default;
268   267  
269   /** Releases the current context's shared ownership and acquires 268   /** Releases the current context's shared ownership and acquires
270   shared ownership of `other`'s underlying state. 269   shared ownership of `other`'s underlying state.
271   270  
272   @param other The context to copy from. 271   @param other The context to copy from.
273   272  
274   @return Reference to this context. 273   @return Reference to this context.
275   */ 274   */
HITCBC 276   1 tls_context& operator=(tls_context const& other) = default; 275   1 tls_context& operator=(tls_context const& other) = default;
277   276  
278   /** Transfers ownership of the TLS context from another instance. 277   /** Transfers ownership of the TLS context from another instance.
279   After the move, `other` is in a valid but empty state. 278   After the move, `other` is in a valid but empty state.
280   279  
281   @param other The context to move from. 280   @param other The context to move from.
282   */ 281   */
HITCBC 283   2 tls_context(tls_context&& other) noexcept = default; 282   2 tls_context(tls_context&& other) noexcept = default;
284   283  
285   /** Releases the current context's shared ownership and transfers 284   /** Releases the current context's shared ownership and transfers
286   ownership from another instance. After the move, `other` is 285   ownership from another instance. After the move, `other` is
287   in a valid but empty state. 286   in a valid but empty state.
288   287  
289   @param other The context to move from. 288   @param other The context to move from.
290   289  
291   @return Reference to this context. 290   @return Reference to this context.
292   */ 291   */
HITCBC 293   1 tls_context& operator=(tls_context&& other) noexcept = default; 292   1 tls_context& operator=(tls_context&& other) noexcept = default;
294   293  
295   /** Releases this handle's shared ownership of the underlying 294   /** Releases this handle's shared ownership of the underlying
296   context. The context state is destroyed when the last handle 295   context. The context state is destroyed when the last handle
297   is released. 296   is released.
298   */ 297   */
HITCBC 299   55 ~tls_context() = default; 298   56 ~tls_context() = default;
300   299  
301   // 300   //
302   // Credential Loading 301   // Credential Loading
303   // 302   //
304   303  
305   /** Load the entity certificate from a memory buffer. 304   /** Load the entity certificate from a memory buffer.
306   305  
307   Sets the certificate that identifies this endpoint to the peer. 306   Sets the certificate that identifies this endpoint to the peer.
308   For servers, this is the server certificate. For clients using 307   For servers, this is the server certificate. For clients using
309   mutual TLS, this is the client certificate. 308   mutual TLS, this is the client certificate.
310   309  
311   The certificate must match the private key loaded via 310   The certificate must match the private key loaded via
312   `use_private_key()` or `use_private_key_file()`. 311   `use_private_key()` or `use_private_key_file()`.
313   312  
314   @param certificate The certificate data. 313   @param certificate The certificate data.
315   314  
316   @param format The encoding format of the certificate data. 315   @param format The encoding format of the certificate data.
317   316  
318   @return Success. The certificate is recorded and decoded when the 317   @return Success. The certificate is recorded and decoded when the
319   native context is first built; a malformed certificate surfaces 318   native context is first built; a malformed certificate surfaces
320   as a handshake failure. 319   as a handshake failure.
321   320  
322   @see use_certificate_file 321   @see use_certificate_file
323   @see use_private_key 322   @see use_private_key
324   */ 323   */
325   [[nodiscard]] std::error_code 324   [[nodiscard]] std::error_code
326   use_certificate(std::string_view certificate, tls_file_format format); 325   use_certificate(std::string_view certificate, tls_file_format format);
327   326  
328   /** Load the entity certificate from a file. 327   /** Load the entity certificate from a file.
329   328  
330   Sets the certificate that identifies this endpoint to the peer. 329   Sets the certificate that identifies this endpoint to the peer.
331   For servers, this is the server certificate. For clients using 330   For servers, this is the server certificate. For clients using
332   mutual TLS, this is the client certificate. 331   mutual TLS, this is the client certificate.
333   332  
334   @param filename Path to the certificate file. 333   @param filename Path to the certificate file.
335   334  
336   @param format The encoding format of the file. 335   @param format The encoding format of the file.
337   336  
338   @return Success, or an error if the file could not be read. The 337   @return Success, or an error if the file could not be read. The
339   certificate is decoded when the native context is first built; 338   certificate is decoded when the native context is first built;
340   a malformed certificate surfaces as a handshake failure. 339   a malformed certificate surfaces as a handshake failure.
341   340  
342   @par Example 341   @par Example
343   @par !example use_certificate_file 342   @par !example use_certificate_file
344   343  
345   @see use_certificate 344   @see use_certificate
346   @see use_private_key_file 345   @see use_private_key_file
347   */ 346   */
348   [[nodiscard]] std::error_code 347   [[nodiscard]] std::error_code
349   use_certificate_file(std::string_view filename, tls_file_format format); 348   use_certificate_file(std::string_view filename, tls_file_format format);
350   349  
351   /** Load a certificate chain from a memory buffer. 350   /** Load a certificate chain from a memory buffer.
352   351  
353   Loads the entity certificate followed by intermediate CA certificates. 352   Loads the entity certificate followed by intermediate CA certificates.
354   The chain should be ordered from leaf to root (excluding the root). 353   The chain should be ordered from leaf to root (excluding the root).
355   This is the typical format for PEM certificate bundles. 354   This is the typical format for PEM certificate bundles.
356   355  
357   @param chain The certificate chain data in PEM format (concatenated 356   @param chain The certificate chain data in PEM format (concatenated
358   certificates). 357   certificates).
359   358  
360   @return Success. The chain is recorded and decoded when the native 359   @return Success. The chain is recorded and decoded when the native
361   context is first built; a malformed chain surfaces as a 360   context is first built; a malformed chain surfaces as a
362   handshake failure. 361   handshake failure.
363   362  
364   @see use_certificate_chain_file 363   @see use_certificate_chain_file
365   */ 364   */
366   [[nodiscard]] std::error_code use_certificate_chain(std::string_view chain); 365   [[nodiscard]] std::error_code use_certificate_chain(std::string_view chain);
367   366  
368   /** Load a certificate chain from a file. 367   /** Load a certificate chain from a file.
369   368  
370   Loads the entity certificate followed by intermediate CA certificates 369   Loads the entity certificate followed by intermediate CA certificates
371   from a PEM file. The file should contain concatenated PEM certificates 370   from a PEM file. The file should contain concatenated PEM certificates
372   ordered from leaf to root (excluding the root). 371   ordered from leaf to root (excluding the root).
373   372  
374   @param filename Path to the certificate chain file. 373   @param filename Path to the certificate chain file.
375   374  
376   @return Success, or an error if the file could not be read. The 375   @return Success, or an error if the file could not be read. The
377   chain is decoded when the native context is first built; a 376   chain is decoded when the native context is first built; a
378   malformed chain surfaces as a handshake failure. 377   malformed chain surfaces as a handshake failure.
379   378  
380   @par Example 379   @par Example
381   @par !example use_certificate_chain_file 380   @par !example use_certificate_chain_file
382   381  
383   @see use_certificate_chain 382   @see use_certificate_chain
384   */ 383   */
385   [[nodiscard]] std::error_code 384   [[nodiscard]] std::error_code
386   use_certificate_chain_file(std::string_view filename); 385   use_certificate_chain_file(std::string_view filename);
387   386  
388   /** Load the private key from a memory buffer. 387   /** Load the private key from a memory buffer.
389   388  
390   Sets the private key corresponding to the entity certificate. 389   Sets the private key corresponding to the entity certificate.
391   The key must match the certificate loaded via `use_certificate()` 390   The key must match the certificate loaded via `use_certificate()`
392   or `use_certificate_chain()`. 391   or `use_certificate_chain()`.
393   392  
394   If the key is encrypted, set a password callback via 393   If the key is encrypted, set a password callback via
395   `set_password_callback()` before calling this function. 394   `set_password_callback()` before calling this function.
396   395  
397   @param private_key The private key data. 396   @param private_key The private key data.
398   397  
399   @param format The encoding format of the key data. 398   @param format The encoding format of the key data.
400   399  
401   @return Success. The key is recorded and decoded when the native 400   @return Success. The key is recorded and decoded when the native
402   context is first built. Three faults surface only as a handshake 401   context is first built. Three faults surface only as a handshake
403   failure: a malformed key, a missing password callback for an 402   failure: a malformed key, a missing password callback for an
404   encrypted key, and a certificate mismatch. 403   encrypted key, and a certificate mismatch.
405   404  
406   @see use_private_key_file 405   @see use_private_key_file
407   @see set_password_callback 406   @see set_password_callback
408   */ 407   */
409   [[nodiscard]] std::error_code 408   [[nodiscard]] std::error_code
410   use_private_key(std::string_view private_key, tls_file_format format); 409   use_private_key(std::string_view private_key, tls_file_format format);
411   410  
412   /** Load the private key from a file. 411   /** Load the private key from a file.
413   412  
414   Sets the private key corresponding to the entity certificate. 413   Sets the private key corresponding to the entity certificate.
415   The key must match the certificate loaded via `use_certificate_file()` 414   The key must match the certificate loaded via `use_certificate_file()`
416   or `use_certificate_chain_file()`. 415   or `use_certificate_chain_file()`.
417   416  
418   If the key file is encrypted, set a password callback via 417   If the key file is encrypted, set a password callback via
419   `set_password_callback()` before calling this function. 418   `set_password_callback()` before calling this function.
420   419  
421   @param filename Path to the private key file. 420   @param filename Path to the private key file.
422   421  
423   @param format The encoding format of the file. 422   @param format The encoding format of the file.
424   423  
425   @return Success, or an error if the file could not be read. The 424   @return Success, or an error if the file could not be read. The
426   key is decoded when the native context is first built; a 425   key is decoded when the native context is first built; a
427   malformed key or a certificate mismatch surfaces as a 426   malformed key or a certificate mismatch surfaces as a
428   handshake failure. 427   handshake failure.
429   428  
430   @par Example 429   @par Example
431   @par !example use_private_key_file 430   @par !example use_private_key_file
432   431  
433   @see use_private_key 432   @see use_private_key
434   @see set_password_callback 433   @see set_password_callback
435   */ 434   */
436   [[nodiscard]] std::error_code 435   [[nodiscard]] std::error_code
437   use_private_key_file(std::string_view filename, tls_file_format format); 436   use_private_key_file(std::string_view filename, tls_file_format format);
438   437  
439   /** Load credentials from a PKCS#12 bundle in memory. 438   /** Load credentials from a PKCS#12 bundle in memory.
440   439  
441   PKCS#12 (also known as PFX) is a binary format that bundles a 440   PKCS#12 (also known as PFX) is a binary format that bundles a
442   certificate, private key, and optionally intermediate certificates 441   certificate, private key, and optionally intermediate certificates
443   into a single password-protected file. 442   into a single password-protected file.
444   443  
445   @param data The PKCS#12 bundle data. 444   @param data The PKCS#12 bundle data.
446   445  
447   @param passphrase The password protecting the bundle. 446   @param passphrase The password protecting the bundle.
448   447  
449   @return Success. The bundle is recorded and decoded into the 448   @return Success. The bundle is recorded and decoded into the
450   certificate, private key, and chain when the native context is 449   certificate, private key, and chain when the native context is
451   first built. A malformed bundle or a wrong passphrase surfaces as a 450   first built. A malformed bundle or a wrong passphrase surfaces as a
452   handshake failure. 451   handshake failure.
453   452  
454   @note Intermediate certificates inside the bundle are loaded and 453   @note Intermediate certificates inside the bundle are loaded and
455   sent during the handshake on both backends. 454   sent during the handshake on both backends.
456   455  
457   @see use_pkcs12_file 456   @see use_pkcs12_file
458   */ 457   */
459   [[nodiscard]] std::error_code 458   [[nodiscard]] std::error_code
460   use_pkcs12(std::string_view data, std::string_view passphrase); 459   use_pkcs12(std::string_view data, std::string_view passphrase);
461   460  
462   /** Load credentials from a PKCS#12 file. 461   /** Load credentials from a PKCS#12 file.
463   462  
464   PKCS#12 (also known as PFX) is a binary format that bundles a 463   PKCS#12 (also known as PFX) is a binary format that bundles a
465   certificate, private key, and optionally intermediate certificates 464   certificate, private key, and optionally intermediate certificates
466   into a single password-protected file. This is common on Windows 465   into a single password-protected file. This is common on Windows
467   and for certificates exported from browsers. 466   and for certificates exported from browsers.
468   467  
469   @param filename Path to the PKCS#12 file. 468   @param filename Path to the PKCS#12 file.
470   469  
471   @param passphrase The password protecting the file. 470   @param passphrase The password protecting the file.
472   471  
473   @return Success, or an error if the file could not be read. The 472   @return Success, or an error if the file could not be read. The
474   bundle is decoded when the native context is first built; a 473   bundle is decoded when the native context is first built; a
475   malformed bundle or wrong passphrase surfaces as a handshake 474   malformed bundle or wrong passphrase surfaces as a handshake
476   failure. 475   failure.
477   476  
478   @note Intermediate certificates inside the bundle are loaded and 477   @note Intermediate certificates inside the bundle are loaded and
479   sent during the handshake on both backends. 478   sent during the handshake on both backends.
480   479  
481   @par Example 480   @par Example
482   @par !example use_pkcs12_file 481   @par !example use_pkcs12_file
483   482  
484   @see use_pkcs12 483   @see use_pkcs12
485   */ 484   */
486   [[nodiscard]] std::error_code 485   [[nodiscard]] std::error_code
487   use_pkcs12_file(std::string_view filename, std::string_view passphrase); 486   use_pkcs12_file(std::string_view filename, std::string_view passphrase);
488   487  
489   // 488   //
490   // Trust Anchors 489   // Trust Anchors
491   // 490   //
492   491  
493   /** Add a certificate authority for peer verification. 492   /** Add a certificate authority for peer verification.
494   493  
495 - Adds a single CA certificate to the trust store used for verifying 494 + Adds one or more CA certificates to the trust store used for
496 - peer certificates. Call this multiple times to add multiple CAs, 495 + verifying peer certificates. The data may contain multiple
497 - or use `load_verify_file()` for a bundle. 496 + concatenated PEM certificates.
498   497  
499   @param ca The CA certificate data in PEM format. 498   @param ca The CA certificate data in PEM format.
500   499  
501 - @return Success. The certificate is recorded and decoded when the 500 + @return Success. The certificates are recorded and decoded when
502 - native context is first built; a malformed certificate 501 + the native context is first built. Whether a malformed
503 - surfaces as a handshake failure. 502 + certificate fails the handshake depends on the backend. On
  503 + OpenSSL, any one does. WolfSSL skips certificates it cannot
  504 + use and fails only when none load.
504   505  
505   @see load_verify_file 506   @see load_verify_file
506   @see set_default_verify_paths 507   @see set_default_verify_paths
507   */ 508   */
508   [[nodiscard]] std::error_code 509   [[nodiscard]] std::error_code
509   add_certificate_authority(std::string_view ca); 510   add_certificate_authority(std::string_view ca);
510   511  
511   /** Load CA certificates from a file. 512   /** Load CA certificates from a file.
512   513  
513   Loads one or more CA certificates from a PEM file. The file may 514   Loads one or more CA certificates from a PEM file. The file may
514   contain multiple concatenated PEM certificates. 515   contain multiple concatenated PEM certificates.
515   516  
516   @param filename Path to a PEM file containing CA certificates. 517   @param filename Path to a PEM file containing CA certificates.
517   518  
518   @return Success, or an error if the file could not be read. The 519   @return Success, or an error if the file could not be read. The
519   certificates are decoded when the native context is first 520   certificates are decoded when the native context is first
520 - built; malformed certificates surface as a handshake failure. 521 + built. Malformed certificates are handled as described for
  522 + `add_certificate_authority()`.
521   523  
522   @par Example 524   @par Example
523   @par !example load_verify_file 525   @par !example load_verify_file
524   526  
525   @see add_certificate_authority 527   @see add_certificate_authority
526   @see add_verify_path 528   @see add_verify_path
527   */ 529   */
528   [[nodiscard]] std::error_code load_verify_file(std::string_view filename); 530   [[nodiscard]] std::error_code load_verify_file(std::string_view filename);
529   531  
530   /** Add a directory of CA certificates for verification. 532   /** Add a directory of CA certificates for verification.
531   533  
532   Adds a directory of CA certificates to the trust store. The 534   Adds a directory of CA certificates to the trust store. The
533   directory is applied when the native context is first built from 535   directory is applied when the native context is first built from
534   this context. 536   this context.
535   537  
536   The expected directory layout depends on the backend. OpenSSL 538   The expected directory layout depends on the backend. OpenSSL
537   performs on-demand lookups. Each certificate file must be named 539   performs on-demand lookups. Each certificate file must be named
538   by its subject-name hash, as generated by `openssl rehash` or 540   by its subject-name hash, as generated by `openssl rehash` or
539   `c_rehash`. WolfSSL loads every certificate file in the 541   `c_rehash`. WolfSSL loads every certificate file in the
540   directory. 542   directory.
541   543  
542   @param path Path to the directory of CA certificates. 544   @param path Path to the directory of CA certificates.
543   545  
544   @return Success. The path is recorded and applied when the native 546   @return Success. The path is recorded and applied when the native
545   context is built. A directory that cannot be read at that time is 547   context is built. A directory that cannot be read at that time is
546   skipped rather than reported here. 548   skipped rather than reported here.
547   549  
548   @par Example 550   @par Example
549   @par !example add_verify_path 551   @par !example add_verify_path
550   552  
551   @see load_verify_file 553   @see load_verify_file
552   @see set_default_verify_paths 554   @see set_default_verify_paths
553   */ 555   */
554   [[nodiscard]] std::error_code add_verify_path(std::string_view path); 556   [[nodiscard]] std::error_code add_verify_path(std::string_view path);
555   557  
556   /** Use the system default CA certificate store. 558   /** Use the system default CA certificate store.
557   559  
558 - Configures the context to use the operating system's default 560 + Configures the context to use the backend's default trust store
559 - trust store for peer certificate verification. This is the 561 + for peer certificate verification. This is the
560   recommended approach for HTTPS clients connecting to public 562   recommended approach for HTTPS clients connecting to public
561   servers. 563   servers.
562   564  
563   The system store is loaded when the native context is first built 565   The system store is loaded when the native context is first built
564   from this context. For a verified-safe client, combine this with 566   from this context. For a verified-safe client, combine this with
565   `set_verify_mode( tls_verify_mode::peer )` and, when connecting by 567   `set_verify_mode( tls_verify_mode::peer )` and, when connecting by
566   name, `tls_stream::set_hostname()`. 568   name, `tls_stream::set_hostname()`.
567   569  
568   @return Success. The request is recorded and applied when the 570   @return Success. The request is recorded and applied when the
569   native context is built. A system store that cannot be loaded at 571   native context is built. A system store that cannot be loaded at
570   that time is skipped rather than reported here. A context that 572   that time is skipped rather than reported here. A context that
571   must reject unverified peers should therefore also use 573   must reject unverified peers should therefore also use
572   `set_verify_mode( tls_verify_mode::peer )`. 574   `set_verify_mode( tls_verify_mode::peer )`.
573   575  
574 - @note The OpenSSL backend honors the `SSL_CERT_FILE` and 576 + @note OpenSSL reads the CA file and directory it was built with,
575 - `SSL_CERT_DIR` environment variables. The WolfSSL backend 577 + or those named by `SSL_CERT_FILE` and `SSL_CERT_DIR`. It does
576 - requires a build with `WOLFSSL_SYS_CA_CERTS`; without it the 578 + not read the macOS Keychain or the Windows Certificate Store.
577 - system store is unavailable and this call has no effect. 579 + WolfSSL reads the platform store and requires a build with
  580 + `WOLFSSL_SYS_CA_CERTS`; without it this call has no effect.
578   581  
579   @par Example 582   @par Example
580   @par !example set_default_verify_paths 583   @par !example set_default_verify_paths
581   584  
582   @see load_verify_file 585   @see load_verify_file
583   @see add_verify_path 586   @see add_verify_path
584   @see set_verify_mode 587   @see set_verify_mode
585   */ 588   */
586   [[nodiscard]] std::error_code set_default_verify_paths(); 589   [[nodiscard]] std::error_code set_default_verify_paths();
587   590  
588   // 591   //
589   // Protocol Configuration 592   // Protocol Configuration
590   // 593   //
591   594  
592   /** Set the minimum TLS protocol version. 595   /** Set the minimum TLS protocol version.
593   596  
594   Connections reject protocol versions older than this. 597   Connections reject protocol versions older than this.
595   The default allows TLS 1.2 and newer. 598   The default allows TLS 1.2 and newer.
596   599  
597   @param v The minimum protocol version to accept. 600   @param v The minimum protocol version to accept.
598   601  
599   @return Success. The version is recorded and applied when the 602   @return Success. The version is recorded and applied when the
600   native context is first built. 603   native context is first built.
601   604  
602   @par Example 605   @par Example
603   @par !example set_min_protocol_version 606   @par !example set_min_protocol_version
604   607  
605   @see set_max_protocol_version 608   @see set_max_protocol_version
606   */ 609   */
607   [[nodiscard]] std::error_code set_min_protocol_version(tls_version v); 610   [[nodiscard]] std::error_code set_min_protocol_version(tls_version v);
608   611  
609   /** Set the maximum TLS protocol version. 612   /** Set the maximum TLS protocol version.
610   613  
611   Connections do not negotiate protocol versions newer than this. 614   Connections do not negotiate protocol versions newer than this.
612   The default allows the newest supported version. 615   The default allows the newest supported version.
613   616  
614   @param v The maximum protocol version to accept. 617   @param v The maximum protocol version to accept.
615   618  
616   @return Success. The version is recorded and applied when the 619   @return Success. The version is recorded and applied when the
617   native context is first built. 620   native context is first built.
618   621  
619   @note On WolfSSL the ceiling is applied by selecting a 622   @note On WolfSSL the ceiling is applied by selecting a
620   version-specific method, because no native set-max API exists. An 623   version-specific method, because no native set-max API exists. An
621   invalid window, where the minimum exceeds the maximum, yields a 624   invalid window, where the minimum exceeds the maximum, yields a
622   context that fails the handshake. 625   context that fails the handshake.
623   626  
624   @see set_min_protocol_version 627   @see set_min_protocol_version
625   */ 628   */
626   [[nodiscard]] std::error_code set_max_protocol_version(tls_version v); 629   [[nodiscard]] std::error_code set_max_protocol_version(tls_version v);
627   630  
628   /** Set the allowed cipher suites. 631   /** Set the allowed cipher suites.
629   632  
630   Configures which cipher suites may be used for connections. 633   Configures which cipher suites may be used for connections.
631   The format is backend-specific but typically follows OpenSSL 634   The format is backend-specific but typically follows OpenSSL
632   cipher list syntax. 635   cipher list syntax.
633   636  
634   @param ciphers The cipher suite specification string. 637   @param ciphers The cipher suite specification string.
635   638  
636   @return Success. The string is recorded and applied when the 639   @return Success. The string is recorded and applied when the
637   native context is first built; an invalid cipher string 640   native context is first built; an invalid cipher string
638   surfaces as a handshake failure. 641   surfaces as a handshake failure.
639   642  
640   @par Example 643   @par Example
641   @par !example set_ciphersuites 644   @par !example set_ciphersuites
642   645  
643   @note This configures cipher suites for TLS 1.2 and below. For 646   @note This configures cipher suites for TLS 1.2 and below. For
644   TLS 1.3, use @ref set_ciphersuites_tls13. 647   TLS 1.3, use @ref set_ciphersuites_tls13.
645   */ 648   */
646   [[nodiscard]] std::error_code set_ciphersuites(std::string_view ciphers); 649   [[nodiscard]] std::error_code set_ciphersuites(std::string_view ciphers);
647   650  
648   /** Set the allowed TLS 1.3 cipher suites. 651   /** Set the allowed TLS 1.3 cipher suites.
649   652  
650   TLS 1.3 uses a distinct, fixed set of cipher suites configured 653   TLS 1.3 uses a distinct, fixed set of cipher suites configured
651   separately from earlier versions. The format is a colon-separated 654   separately from earlier versions. The format is a colon-separated
652   list of TLS 1.3 suite names. 655   list of TLS 1.3 suite names.
653   656  
654   @param ciphers The TLS 1.3 cipher suite list. 657   @param ciphers The TLS 1.3 cipher suite list.
655   658  
656   @return Success. The string is recorded and applied when the 659   @return Success. The string is recorded and applied when the
657   native context is first built; an invalid cipher string 660   native context is first built; an invalid cipher string
658   surfaces as a handshake failure. 661   surfaces as a handshake failure.
659   662  
660   @par Example 663   @par Example
661   @par !example set_ciphersuites_tls13 664   @par !example set_ciphersuites_tls13
662   665  
663   @note On the WolfSSL backend, TLS 1.2 and TLS 1.3 suites share a 666   @note On the WolfSSL backend, TLS 1.2 and TLS 1.3 suites share a
664   single cipher list; this call and @ref set_ciphersuites are 667   single cipher list; this call and @ref set_ciphersuites are
665   merged into one list. 668   merged into one list.
666   669  
667   @see set_ciphersuites 670   @see set_ciphersuites
668   */ 671   */
669   [[nodiscard]] std::error_code 672   [[nodiscard]] std::error_code
670   set_ciphersuites_tls13(std::string_view ciphers); 673   set_ciphersuites_tls13(std::string_view ciphers);
671   674  
672   /** Set the ALPN protocol list. 675   /** Set the ALPN protocol list.
673   676  
674   Configures Application-Layer Protocol Negotiation (ALPN) for 677   Configures Application-Layer Protocol Negotiation (ALPN) for
675   the connection. ALPN is used to negotiate which application 678   the connection. ALPN is used to negotiate which application
676   protocol to use over the TLS connection (e.g., "h2" for HTTP/2, 679   protocol to use over the TLS connection (e.g., "h2" for HTTP/2,
677   "http/1.1" for HTTP/1.1). 680   "http/1.1" for HTTP/1.1).
678   681  
679   The protocols are tried in preference order (first = highest). 682   The protocols are tried in preference order (first = highest).
680   683  
681   @param protocols Ordered list of protocol identifiers. 684   @param protocols Ordered list of protocol identifiers.
682   685  
683   @return Success, or an error if ALPN configuration fails. 686   @return Success, or an error if ALPN configuration fails.
684   687  
685   @note Read the negotiated protocol after the handshake via 688   @note Read the negotiated protocol after the handshake via
686   @ref tls_stream::alpn_protocol. On WolfSSL, ALPN requires a 689   @ref tls_stream::alpn_protocol. On WolfSSL, ALPN requires a
687   build with `HAVE_ALPN`; without it, offering protocols fails 690   build with `HAVE_ALPN`; without it, offering protocols fails
688   the handshake with `std::errc::function_not_supported` rather 691   the handshake with `std::errc::function_not_supported` rather
689   than negotiate nothing silently. 692   than negotiate nothing silently.
690   693  
691   @par Example 694   @par Example
692   @par !example set_alpn 695   @par !example set_alpn
693   */ 696   */
694   [[nodiscard]] std::error_code 697   [[nodiscard]] std::error_code
695   set_alpn(std::initializer_list<std::string_view> protocols); 698   set_alpn(std::initializer_list<std::string_view> protocols);
696   699  
697   // 700   //
698   // Certificate Verification 701   // Certificate Verification
699   // 702   //
700   703  
701   /** Set the peer certificate verification mode. 704   /** Set the peer certificate verification mode.
702   705  
703   Controls whether and how peer certificates are verified during 706   Controls whether and how peer certificates are verified during
704   the TLS handshake. 707   the TLS handshake.
705   708  
706   @param mode The verification mode to use. 709   @param mode The verification mode to use.
707   710  
708   @return Success. The mode is recorded and applied when the native 711   @return Success. The mode is recorded and applied when the native
709   context is first built. 712   context is first built.
710   713  
711   @par Example 714   @par Example
712   @par !example set_verify_mode 715   @par !example set_verify_mode
713   716  
714   @see tls_verify_mode 717   @see tls_verify_mode
715   */ 718   */
716   [[nodiscard]] std::error_code set_verify_mode(tls_verify_mode mode); 719   [[nodiscard]] std::error_code set_verify_mode(tls_verify_mode mode);
717   720  
718   /** Set the maximum certificate chain verification depth. 721   /** Set the maximum certificate chain verification depth.
719   722  
720   Limits how many intermediate certificates can appear between 723   Limits how many intermediate certificates can appear between
721   the peer certificate and a trusted root. The default is 724   the peer certificate and a trusted root. The default is
722   typically 100, which is sufficient for most certificate chains. 725   typically 100, which is sufficient for most certificate chains.
723   726  
724   @param depth Maximum number of intermediate certificates allowed. 727   @param depth Maximum number of intermediate certificates allowed.
725   728  
726   @return Success. The depth is recorded and applied when the native 729   @return Success. The depth is recorded and applied when the native
727   context is first built. 730   context is first built.
728   731  
729   @par Example 732   @par Example
730   @par !example set_verify_depth 733   @par !example set_verify_depth
731   */ 734   */
732   [[nodiscard]] std::error_code set_verify_depth(int depth); 735   [[nodiscard]] std::error_code set_verify_depth(int depth);
733   736  
734   /** Set a custom certificate verification callback. 737   /** Set a custom certificate verification callback.
735   738  
736   Installs a callback that is invoked during certificate chain 739   Installs a callback that is invoked during certificate chain
737   verification. The callback can perform additional validation 740   verification. The callback can perform additional validation
738   beyond the standard checks and can override verification 741   beyond the standard checks and can override verification
739   results. 742   results.
740   743  
741   The callback receives the built-in verification result so far and 744   The callback receives the built-in verification result so far and
742   a `verify_context` describing the certificate being verified. Return 745   a `verify_context` describing the certificate being verified. Return
743   `true` to accept the certificate, `false` to reject. Inspect the 746   `true` to accept the certificate, `false` to reject. Inspect the
744   certificate portably via `verify_context::certificate()` (its DER 747   certificate portably via `verify_context::certificate()` (its DER
745   encoding) — for example to pin a specific certificate. 748   encoding) — for example to pin a specific certificate.
746   749  
747   @par Backend Support 750   @par Backend Support
748   751  
749   The exact set of certificates the callback sees differs by backend: 752   The exact set of certificates the callback sees differs by backend:
750   753  
751   - OpenSSL: the callback runs once per certificate in the chain, 754   - OpenSSL: the callback runs once per certificate in the chain,
752   including certificates that passed the built-in checks. It can 755   including certificates that passed the built-in checks. It can
753   therefore relax verification by returning `true` for a 756   therefore relax verification by returning `true` for a
754   certificate the library rejected. It can also tighten 757   certificate the library rejected. It can also tighten
755   verification by returning `false` for a certificate the library 758   verification by returning `false` for a certificate the library
756   accepted, as pinning does. 759   accepted, as pinning does.
757   - WolfSSL built with `WOLFSSL_ALWAYS_VERIFY_CB` (implied by 760   - WolfSSL built with `WOLFSSL_ALWAYS_VERIFY_CB` (implied by
758   `--enable-opensslextra`): same as OpenSSL. 761   `--enable-opensslextra`): same as OpenSSL.
759   - WolfSSL without that option: the library invokes the callback 762   - WolfSSL without that option: the library invokes the callback
760   only on verification *failure*, so it cannot be honored on a 763   only on verification *failure*, so it cannot be honored on a
761   successful handshake. Silently ignoring a verification-tightening 764   successful handshake. Silently ignoring a verification-tightening
762   callback would fail open. On such a build, a context that carries 765   callback would fail open. On such a build, a context that carries
763   a callback instead **fails the handshake** with 766   a callback instead **fails the handshake** with
764   `std::errc::function_not_supported`. Rebuild 767   `std::errc::function_not_supported`. Rebuild
765   WolfSSL with `WOLFSSL_ALWAYS_VERIFY_CB`, or omit the callback. 768   WolfSSL with `WOLFSSL_ALWAYS_VERIFY_CB`, or omit the callback.
766   769  
767   @tparam Callback A callable with signature 770   @tparam Callback A callable with signature
768   `bool( bool preverified, verify_context& ctx )`. 771   `bool( bool preverified, verify_context& ctx )`.
769   772  
770   @param callback The verification callback. Recorded here and 773   @param callback The verification callback. Recorded here and
771   applied during the handshake; on a WolfSSL build that 774   applied during the handshake; on a WolfSSL build that
772   cannot honor it, the handshake fails with 775   cannot honor it, the handshake fails with
773   `std::errc::function_not_supported` (see Backend Support). 776   `std::errc::function_not_supported` (see Backend Support).
774   777  
775   @par Example 778   @par Example
776   @par !example set_verify_callback 779   @par !example set_verify_callback
777   780  
778   @see verify_context 781   @see verify_context
779   @see set_verify_mode 782   @see set_verify_mode
780   */ 783   */
781   template<typename Callback> 784   template<typename Callback>
782   void set_verify_callback(Callback callback); 785   void set_verify_callback(Callback callback);
783   786  
784   /** Set a callback for Server Name Indication (SNI). 787   /** Set a callback for Server Name Indication (SNI).
785   788  
786   For server connections, this callback is invoked during the TLS 789   For server connections, this callback is invoked during the TLS
787   handshake when a client sends an SNI extension. The callback 790   handshake when a client sends an SNI extension. The callback
788   receives the requested hostname and can accept or reject the 791   receives the requested hostname and can accept or reject the
789   connection. 792   connection.
790   793  
791   @tparam Callback A callable with signature 794   @tparam Callback A callable with signature
792   `bool( std::string_view hostname )`. 795   `bool( std::string_view hostname )`.
793   796  
794   @param callback The SNI callback. Return `true` to accept the 797   @param callback The SNI callback. Return `true` to accept the
795   connection or `false` to reject it with an alert. 798   connection or `false` to reject it with an alert.
796   799  
797   @par Example 800   @par Example
798   @par !example set_servername_callback 801   @par !example set_servername_callback
799   802  
800   @note For virtual hosting with different certificates per hostname, 803   @note For virtual hosting with different certificates per hostname,
801   create separate contexts and select the appropriate one before 804   create separate contexts and select the appropriate one before
802   creating the TLS stream. 805   creating the TLS stream.
803   806  
804   @see tls_stream::set_hostname 807   @see tls_stream::set_hostname
805   */ 808   */
806   template<typename Callback> 809   template<typename Callback>
807   void set_servername_callback(Callback callback); 810   void set_servername_callback(Callback callback);
808   811  
809   private: 812   private:
810   void set_servername_callback_impl( 813   void set_servername_callback_impl(
811   std::function<bool(std::string_view)> callback); 814   std::function<bool(std::string_view)> callback);
812   815  
813   void set_password_callback_impl( 816   void set_password_callback_impl(
814   std::function<std::string(std::size_t, tls_password_purpose)> callback); 817   std::function<std::string(std::size_t, tls_password_purpose)> callback);
815   818  
816   void set_verify_callback_impl( 819   void set_verify_callback_impl(
817   std::function<bool(bool, verify_context&)> callback); 820   std::function<bool(bool, verify_context&)> callback);
818   821  
819   public: 822   public:
820   // 823   //
821   // Revocation Checking 824   // Revocation Checking
822   // 825   //
823   826  
824   /** Add a Certificate Revocation List from memory. 827   /** Add a Certificate Revocation List from memory.
825   828  
826   Adds a CRL to the verification store for checking whether 829   Adds a CRL to the verification store for checking whether
827   certificates are revoked. CRLs are typically fetched 830   certificates are revoked. CRLs are typically fetched
828   from the URLs in a certificate's CRL Distribution Points 831   from the URLs in a certificate's CRL Distribution Points
829   extension. 832   extension.
830   833  
831   @param crl The CRL data in DER or PEM format. 834   @param crl The CRL data in DER or PEM format.
832   835  
833   @return Success. The CRL is recorded and decoded when the native 836   @return Success. The CRL is recorded and decoded when the native
834   context is first built; a malformed CRL surfaces as a 837   context is first built; a malformed CRL surfaces as a
835   handshake failure. 838   handshake failure.
836   839  
837   @note CRLs are consulted only when a revocation policy is set via 840   @note CRLs are consulted only when a revocation policy is set via
838   @ref set_revocation_policy. On WolfSSL, CRL checking requires a 841   @ref set_revocation_policy. On WolfSSL, CRL checking requires a
839 - build with `HAVE_CRL`; without it, supplying a CRL or a 842 + build with `HAVE_CRL`; without it, a revocation policy
840 - revocation policy fails the handshake with 843 + other than `disabled` fails the handshake with
841   `std::errc::function_not_supported`. 844   `std::errc::function_not_supported`.
842   845  
843   @see add_crl_file 846   @see add_crl_file
844   @see set_revocation_policy 847   @see set_revocation_policy
845   */ 848   */
846   [[nodiscard]] std::error_code add_crl(std::string_view crl); 849   [[nodiscard]] std::error_code add_crl(std::string_view crl);
847   850  
848   /** Add a Certificate Revocation List from a file. 851   /** Add a Certificate Revocation List from a file.
849   852  
850   Adds a CRL to the verification store for checking whether 853   Adds a CRL to the verification store for checking whether
851   certificates are revoked. 854   certificates are revoked.
852   855  
853   @param filename Path to a CRL file (DER or PEM format). 856   @param filename Path to a CRL file (DER or PEM format).
854   857  
855   @return Success, or an error if the file could not be read. The 858   @return Success, or an error if the file could not be read. The
856   CRL is decoded when the native context is first built; a 859   CRL is decoded when the native context is first built; a
857   malformed CRL surfaces as a handshake failure. 860   malformed CRL surfaces as a handshake failure.
858   861  
859   @note CRLs are consulted only when a revocation policy is set via 862   @note CRLs are consulted only when a revocation policy is set via
860   @ref set_revocation_policy (WolfSSL requires a `HAVE_CRL` 863   @ref set_revocation_policy (WolfSSL requires a `HAVE_CRL`
861   build). 864   build).
862   865  
863   @par Example 866   @par Example
864   @par !example add_crl_file 867   @par !example add_crl_file
865   868  
866   @see add_crl 869   @see add_crl
867   @see set_revocation_policy 870   @see set_revocation_policy
868   */ 871   */
869   [[nodiscard]] std::error_code add_crl_file(std::string_view filename); 872   [[nodiscard]] std::error_code add_crl_file(std::string_view filename);
870   873  
871   /** Set the certificate revocation checking policy. 874   /** Set the certificate revocation checking policy.
872   875  
873   Controls how certificate revocation status is checked during 876   Controls how certificate revocation status is checked during
874   verification via CRLs. 877   verification via CRLs.
875   878  
876   @param policy The revocation checking policy. 879   @param policy The revocation checking policy.
877   880  
878   @par Example 881   @par Example
879   @par !example set_revocation_policy 882   @par !example set_revocation_policy
880   883  
881   @note Revocation is checked via CRLs supplied with @ref add_crl / 884   @note Revocation is checked via CRLs supplied with @ref add_crl /
882   @ref add_crl_file. `soft_fail` accepts a certificate whose 885   @ref add_crl_file. `soft_fail` accepts a certificate whose
883   status cannot be determined (missing/expired CRL) but rejects 886   status cannot be determined (missing/expired CRL) but rejects
884   one that is actually revoked; `hard_fail` also rejects unknown 887   one that is actually revoked; `hard_fail` also rejects unknown
885   status. OCSP-based revocation is not available (see the TLS 888   status. OCSP-based revocation is not available (see the TLS
886   guide). On WolfSSL a non-disabled policy requires a `HAVE_CRL` 889   guide). On WolfSSL a non-disabled policy requires a `HAVE_CRL`
887   build, else the handshake fails with 890   build, else the handshake fails with
888   `std::errc::function_not_supported`. 891   `std::errc::function_not_supported`.
889   892  
890   @see tls_revocation_policy 893   @see tls_revocation_policy
891   @see add_crl 894   @see add_crl
892   */ 895   */
893   void set_revocation_policy(tls_revocation_policy policy); 896   void set_revocation_policy(tls_revocation_policy policy);
894   897  
895   // 898   //
896   // Password Handling 899   // Password Handling
897   // 900   //
898   901  
899   /** Set the password callback for encrypted keys. 902   /** Set the password callback for encrypted keys.
900   903  
901   Installs a callback that provides passwords for encrypted 904   Installs a callback that provides passwords for encrypted
902   private keys and PKCS#12 files. The callback is invoked when 905   private keys and PKCS#12 files. The callback is invoked when
903   loading encrypted key material. 906   loading encrypted key material.
904   907  
905   @tparam Callback A callable with signature 908   @tparam Callback A callable with signature
906   `std::string( std::size_t max_length, tls_password_purpose purpose )`. 909   `std::string( std::size_t max_length, tls_password_purpose purpose )`.
907   910  
908   @param callback The password callback. It receives the maximum 911   @param callback The password callback. It receives the maximum
909   password length and the purpose (reading or writing), and 912   password length and the purpose (reading or writing), and
910   returns the password string. 913   returns the password string.
911   914  
912   @par Example 915   @par Example
913   @par !example set_password_callback 916   @par !example set_password_callback
914   917  
915   @see tls_password_purpose 918   @see tls_password_purpose
916   */ 919   */
917   template<typename Callback> 920   template<typename Callback>
918   void set_password_callback(Callback callback); 921   void set_password_callback(Callback callback);
919   }; 922   };
920   #ifdef _MSC_VER 923   #ifdef _MSC_VER
921   #pragma warning(pop) 924   #pragma warning(pop)
922   #endif 925   #endif
923   926  
924   template<typename Callback> 927   template<typename Callback>
925   void 928   void
HITCBC 926   1 tls_context::set_servername_callback(Callback callback) 929   1 tls_context::set_servername_callback(Callback callback)
927   { 930   {
HITCBC 928   1 set_servername_callback_impl(std::move(callback)); 931   1 set_servername_callback_impl(std::move(callback));
HITCBC 929   1 } 932   1 }
930   933  
931   template<typename Callback> 934   template<typename Callback>
932   void 935   void
HITCBC 933   4 tls_context::set_password_callback(Callback callback) 936   4 tls_context::set_password_callback(Callback callback)
934   { 937   {
HITCBC 935   4 set_password_callback_impl(std::move(callback)); 938   4 set_password_callback_impl(std::move(callback));
HITCBC 936   4 } 939   4 }
937   940  
938   template<typename Callback> 941   template<typename Callback>
939   void 942   void
HITCBC 940   2 tls_context::set_verify_callback(Callback callback) 943   2 tls_context::set_verify_callback(Callback callback)
941   { 944   {
HITCBC 942   2 set_verify_callback_impl(std::move(callback)); 945   2 set_verify_callback_impl(std::move(callback));
HITCBC 943   2 } 946   2 }
944   947  
945   } // namespace boost::corosio 948   } // namespace boost::corosio
946   949  
947   #endif 950   #endif