. /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 the 213 + This class abstracts the configuration phase of TLS across multiple
214 - OpenSSL and WolfSSL backends. Portable code therefore works 214 + backend implementations, among them OpenSSL, WolfSSL, mbedTLS and
215 - regardless of which TLS library is linked. 215 + Schannel. Portable code therefore works regardless of which TLS
  216 + library is linked.
216   217  
217   @par Modification After Stream Creation 218   @par Modification After Stream Creation
218   219  
219   Modifying a context after creating a TLS stream from it 220   Modifying a context after creating a TLS stream from it
220 - results in undefined behavior. Most settings are captured at the 221 + results in undefined behavior. The context's configuration is
221 - first handshake of any stream using it; others, such as callbacks, 222 + captured when the first stream is constructed, and subsequent
222 - are read later. A modification may therefore apply partly or not at 223 + modifications are not reflected in existing or new streams
223 - all. 224 + sharing the context.
224   225  
225   If different configurations are needed, create separate context 226   If different configurations are needed, create separate context
226   objects. 227   objects.
227   228  
228   @par Thread Safety 229   @par Thread Safety
229   230  
230   Distinct objects: Safe. 231   Distinct objects: Safe.
231   232  
232   Shared objects: Unsafe. A context must not be modified while 233   Shared objects: Unsafe. A context must not be modified while
233   any thread is creating streams from it. 234   any thread is creating streams from it.
234   235  
235   @par Example 236   @par Example
236   @par !example tls_context 237   @par !example tls_context
237   238  
238   @see tls_role 239   @see tls_role
239   */ 240   */
240   class BOOST_COROSIO_DECL tls_context 241   class BOOST_COROSIO_DECL tls_context
241   { 242   {
242   struct implementation; 243   struct implementation;
243   std::shared_ptr<implementation> impl_; 244   std::shared_ptr<implementation> impl_;
244   245  
245   friend detail::tls_context_data const& 246   friend detail::tls_context_data const&
246   detail::get_tls_context_data(tls_context const&) noexcept; 247   detail::get_tls_context_data(tls_context const&) noexcept;
247   248  
248   public: 249   public:
249   /** Construct a default TLS context. 250   /** Construct a default TLS context.
250   251  
251   Creates a context with default settings suitable for TLS 1.2 252   Creates a context with default settings suitable for TLS 1.2
252   and TLS 1.3 connections. No certificates or trust anchors are 253   and TLS 1.3 connections. No certificates or trust anchors are
253   loaded; call the appropriate methods to configure credentials 254   loaded; call the appropriate methods to configure credentials
254   and verification. 255   and verification.
255   256  
256   @par Example 257   @par Example
257   @par !example tls_context 258   @par !example tls_context
258   */ 259   */
259   tls_context(); 260   tls_context();
260   261  
261   /** Creates a new handle that shares ownership of the underlying 262   /** Creates a new handle that shares ownership of the underlying
262   TLS context state with `other`. 263   TLS context state with `other`.
263   264  
264   @param other The context to copy from. 265   @param other The context to copy from.
265   */ 266   */
HITCBC 266   2 tls_context(tls_context const& other) = default; 267   2 tls_context(tls_context const& other) = default;
267   268  
268   /** Releases the current context's shared ownership and acquires 269   /** Releases the current context's shared ownership and acquires
269   shared ownership of `other`'s underlying state. 270   shared ownership of `other`'s underlying state.
270   271  
271   @param other The context to copy from. 272   @param other The context to copy from.
272   273  
273   @return Reference to this context. 274   @return Reference to this context.
274   */ 275   */
HITCBC 275   1 tls_context& operator=(tls_context const& other) = default; 276   1 tls_context& operator=(tls_context const& other) = default;
276   277  
277   /** Transfers ownership of the TLS context from another instance. 278   /** Transfers ownership of the TLS context from another instance.
278   After the move, `other` is in a valid but empty state. 279   After the move, `other` is in a valid but empty state.
279   280  
280   @param other The context to move from. 281   @param other The context to move from.
281   */ 282   */
HITCBC 282   2 tls_context(tls_context&& other) noexcept = default; 283   2 tls_context(tls_context&& other) noexcept = default;
283   284  
284   /** Releases the current context's shared ownership and transfers 285   /** Releases the current context's shared ownership and transfers
285   ownership from another instance. After the move, `other` is 286   ownership from another instance. After the move, `other` is
286   in a valid but empty state. 287   in a valid but empty state.
287   288  
288   @param other The context to move from. 289   @param other The context to move from.
289   290  
290   @return Reference to this context. 291   @return Reference to this context.
291   */ 292   */
HITCBC 292   1 tls_context& operator=(tls_context&& other) noexcept = default; 293   1 tls_context& operator=(tls_context&& other) noexcept = default;
293   294  
294   /** Releases this handle's shared ownership of the underlying 295   /** Releases this handle's shared ownership of the underlying
295   context. The context state is destroyed when the last handle 296   context. The context state is destroyed when the last handle
296   is released. 297   is released.
297   */ 298   */
HITCBC 298   56 ~tls_context() = default; 299   55 ~tls_context() = default;
299   300  
300   // 301   //
301   // Credential Loading 302   // Credential Loading
302   // 303   //
303   304  
304   /** Load the entity certificate from a memory buffer. 305   /** Load the entity certificate from a memory buffer.
305   306  
306   Sets the certificate that identifies this endpoint to the peer. 307   Sets the certificate that identifies this endpoint to the peer.
307   For servers, this is the server certificate. For clients using 308   For servers, this is the server certificate. For clients using
308   mutual TLS, this is the client certificate. 309   mutual TLS, this is the client certificate.
309   310  
310   The certificate must match the private key loaded via 311   The certificate must match the private key loaded via
311   `use_private_key()` or `use_private_key_file()`. 312   `use_private_key()` or `use_private_key_file()`.
312   313  
313   @param certificate The certificate data. 314   @param certificate The certificate data.
314   315  
315   @param format The encoding format of the certificate data. 316   @param format The encoding format of the certificate data.
316   317  
317   @return Success. The certificate is recorded and decoded when the 318   @return Success. The certificate is recorded and decoded when the
318   native context is first built; a malformed certificate surfaces 319   native context is first built; a malformed certificate surfaces
319   as a handshake failure. 320   as a handshake failure.
320   321  
321   @see use_certificate_file 322   @see use_certificate_file
322   @see use_private_key 323   @see use_private_key
323   */ 324   */
324   [[nodiscard]] std::error_code 325   [[nodiscard]] std::error_code
325   use_certificate(std::string_view certificate, tls_file_format format); 326   use_certificate(std::string_view certificate, tls_file_format format);
326   327  
327   /** Load the entity certificate from a file. 328   /** Load the entity certificate from a file.
328   329  
329   Sets the certificate that identifies this endpoint to the peer. 330   Sets the certificate that identifies this endpoint to the peer.
330   For servers, this is the server certificate. For clients using 331   For servers, this is the server certificate. For clients using
331   mutual TLS, this is the client certificate. 332   mutual TLS, this is the client certificate.
332   333  
333   @param filename Path to the certificate file. 334   @param filename Path to the certificate file.
334   335  
335   @param format The encoding format of the file. 336   @param format The encoding format of the file.
336   337  
337   @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
338   certificate is decoded when the native context is first built; 339   certificate is decoded when the native context is first built;
339   a malformed certificate surfaces as a handshake failure. 340   a malformed certificate surfaces as a handshake failure.
340   341  
341   @par Example 342   @par Example
342   @par !example use_certificate_file 343   @par !example use_certificate_file
343   344  
344   @see use_certificate 345   @see use_certificate
345   @see use_private_key_file 346   @see use_private_key_file
346   */ 347   */
347   [[nodiscard]] std::error_code 348   [[nodiscard]] std::error_code
348   use_certificate_file(std::string_view filename, tls_file_format format); 349   use_certificate_file(std::string_view filename, tls_file_format format);
349   350  
350   /** Load a certificate chain from a memory buffer. 351   /** Load a certificate chain from a memory buffer.
351   352  
352   Loads the entity certificate followed by intermediate CA certificates. 353   Loads the entity certificate followed by intermediate CA certificates.
353   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).
354   This is the typical format for PEM certificate bundles. 355   This is the typical format for PEM certificate bundles.
355   356  
356   @param chain The certificate chain data in PEM format (concatenated 357   @param chain The certificate chain data in PEM format (concatenated
357   certificates). 358   certificates).
358   359  
359   @return Success. The chain is recorded and decoded when the native 360   @return Success. The chain is recorded and decoded when the native
360   context is first built; a malformed chain surfaces as a 361   context is first built; a malformed chain surfaces as a
361   handshake failure. 362   handshake failure.
362   363  
363   @see use_certificate_chain_file 364   @see use_certificate_chain_file
364   */ 365   */
365   [[nodiscard]] std::error_code use_certificate_chain(std::string_view chain); 366   [[nodiscard]] std::error_code use_certificate_chain(std::string_view chain);
366   367  
367   /** Load a certificate chain from a file. 368   /** Load a certificate chain from a file.
368   369  
369   Loads the entity certificate followed by intermediate CA certificates 370   Loads the entity certificate followed by intermediate CA certificates
370   from a PEM file. The file should contain concatenated PEM certificates 371   from a PEM file. The file should contain concatenated PEM certificates
371   ordered from leaf to root (excluding the root). 372   ordered from leaf to root (excluding the root).
372   373  
373   @param filename Path to the certificate chain file. 374   @param filename Path to the certificate chain file.
374   375  
375   @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
376   chain is decoded when the native context is first built; a 377   chain is decoded when the native context is first built; a
377   malformed chain surfaces as a handshake failure. 378   malformed chain surfaces as a handshake failure.
378   379  
379   @par Example 380   @par Example
380   @par !example use_certificate_chain_file 381   @par !example use_certificate_chain_file
381   382  
382   @see use_certificate_chain 383   @see use_certificate_chain
383   */ 384   */
384   [[nodiscard]] std::error_code 385   [[nodiscard]] std::error_code
385   use_certificate_chain_file(std::string_view filename); 386   use_certificate_chain_file(std::string_view filename);
386   387  
387   /** Load the private key from a memory buffer. 388   /** Load the private key from a memory buffer.
388   389  
389   Sets the private key corresponding to the entity certificate. 390   Sets the private key corresponding to the entity certificate.
390   The key must match the certificate loaded via `use_certificate()` 391   The key must match the certificate loaded via `use_certificate()`
391   or `use_certificate_chain()`. 392   or `use_certificate_chain()`.
392   393  
393   If the key is encrypted, set a password callback via 394   If the key is encrypted, set a password callback via
394   `set_password_callback()` before calling this function. 395   `set_password_callback()` before calling this function.
395   396  
396   @param private_key The private key data. 397   @param private_key The private key data.
397   398  
398   @param format The encoding format of the key data. 399   @param format The encoding format of the key data.
399   400  
400   @return Success. The key is recorded and decoded when the native 401   @return Success. The key is recorded and decoded when the native
401   context is first built. Three faults surface only as a handshake 402   context is first built. Three faults surface only as a handshake
402   failure: a malformed key, a missing password callback for an 403   failure: a malformed key, a missing password callback for an
403   encrypted key, and a certificate mismatch. 404   encrypted key, and a certificate mismatch.
404   405  
405   @see use_private_key_file 406   @see use_private_key_file
406   @see set_password_callback 407   @see set_password_callback
407   */ 408   */
408   [[nodiscard]] std::error_code 409   [[nodiscard]] std::error_code
409   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);
410   411  
411   /** Load the private key from a file. 412   /** Load the private key from a file.
412   413  
413   Sets the private key corresponding to the entity certificate. 414   Sets the private key corresponding to the entity certificate.
414   The key must match the certificate loaded via `use_certificate_file()` 415   The key must match the certificate loaded via `use_certificate_file()`
415   or `use_certificate_chain_file()`. 416   or `use_certificate_chain_file()`.
416   417  
417   If the key file is encrypted, set a password callback via 418   If the key file is encrypted, set a password callback via
418   `set_password_callback()` before calling this function. 419   `set_password_callback()` before calling this function.
419   420  
420   @param filename Path to the private key file. 421   @param filename Path to the private key file.
421   422  
422   @param format The encoding format of the file. 423   @param format The encoding format of the file.
423   424  
424   @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
425   key is decoded when the native context is first built; a 426   key is decoded when the native context is first built; a
426   malformed key or a certificate mismatch surfaces as a 427   malformed key or a certificate mismatch surfaces as a
427   handshake failure. 428   handshake failure.
428   429  
429   @par Example 430   @par Example
430   @par !example use_private_key_file 431   @par !example use_private_key_file
431   432  
432   @see use_private_key 433   @see use_private_key
433   @see set_password_callback 434   @see set_password_callback
434   */ 435   */
435   [[nodiscard]] std::error_code 436   [[nodiscard]] std::error_code
436   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);
437   438  
438   /** Load credentials from a PKCS#12 bundle in memory. 439   /** Load credentials from a PKCS#12 bundle in memory.
439   440  
440   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
441   certificate, private key, and optionally intermediate certificates 442   certificate, private key, and optionally intermediate certificates
442   into a single password-protected file. 443   into a single password-protected file.
443   444  
444   @param data The PKCS#12 bundle data. 445   @param data The PKCS#12 bundle data.
445   446  
446   @param passphrase The password protecting the bundle. 447   @param passphrase The password protecting the bundle.
447   448  
448   @return Success. The bundle is recorded and decoded into the 449   @return Success. The bundle is recorded and decoded into the
449   certificate, private key, and chain when the native context is 450   certificate, private key, and chain when the native context is
450   first built. A malformed bundle or a wrong passphrase surfaces as a 451   first built. A malformed bundle or a wrong passphrase surfaces as a
451   handshake failure. 452   handshake failure.
452   453  
453   @note Intermediate certificates inside the bundle are loaded and 454   @note Intermediate certificates inside the bundle are loaded and
454   sent during the handshake on both backends. 455   sent during the handshake on both backends.
455   456  
456   @see use_pkcs12_file 457   @see use_pkcs12_file
457   */ 458   */
458   [[nodiscard]] std::error_code 459   [[nodiscard]] std::error_code
459   use_pkcs12(std::string_view data, std::string_view passphrase); 460   use_pkcs12(std::string_view data, std::string_view passphrase);
460   461  
461   /** Load credentials from a PKCS#12 file. 462   /** Load credentials from a PKCS#12 file.
462   463  
463   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
464   certificate, private key, and optionally intermediate certificates 465   certificate, private key, and optionally intermediate certificates
465   into a single password-protected file. This is common on Windows 466   into a single password-protected file. This is common on Windows
466   and for certificates exported from browsers. 467   and for certificates exported from browsers.
467   468  
468   @param filename Path to the PKCS#12 file. 469   @param filename Path to the PKCS#12 file.
469   470  
470   @param passphrase The password protecting the file. 471   @param passphrase The password protecting the file.
471   472  
472   @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
473   bundle is decoded when the native context is first built; a 474   bundle is decoded when the native context is first built; a
474   malformed bundle or wrong passphrase surfaces as a handshake 475   malformed bundle or wrong passphrase surfaces as a handshake
475   failure. 476   failure.
476   477  
477   @note Intermediate certificates inside the bundle are loaded and 478   @note Intermediate certificates inside the bundle are loaded and
478   sent during the handshake on both backends. 479   sent during the handshake on both backends.
479   480  
480   @par Example 481   @par Example
481   @par !example use_pkcs12_file 482   @par !example use_pkcs12_file
482   483  
483   @see use_pkcs12 484   @see use_pkcs12
484   */ 485   */
485   [[nodiscard]] std::error_code 486   [[nodiscard]] std::error_code
486   use_pkcs12_file(std::string_view filename, std::string_view passphrase); 487   use_pkcs12_file(std::string_view filename, std::string_view passphrase);
487   488  
488   // 489   //
489   // Trust Anchors 490   // Trust Anchors
490   // 491   //
491   492  
492   /** Add a certificate authority for peer verification. 493   /** Add a certificate authority for peer verification.
493   494  
494 - Adds one or more CA certificates to the trust store used for 495 + Adds a single CA certificate to the trust store used for verifying
495 - verifying peer certificates. The data may contain multiple 496 + peer certificates. Call this multiple times to add multiple CAs,
496 - concatenated PEM certificates. 497 + or use `load_verify_file()` for a bundle.
497   498  
498   @param ca The CA certificate data in PEM format. 499   @param ca The CA certificate data in PEM format.
499   500  
500 - @return Success. The certificates are recorded and decoded when 501 + @return Success. The certificate is recorded and decoded when the
501 - the native context is first built. Whether a malformed 502 + native context is first built; a malformed certificate
502 - certificate fails the handshake depends on the backend. On 503 + surfaces as a handshake failure.
503 - OpenSSL, any one does. WolfSSL skips certificates it cannot  
504 - use and fails only when none load.  
505   504  
506   @see load_verify_file 505   @see load_verify_file
507   @see set_default_verify_paths 506   @see set_default_verify_paths
508   */ 507   */
509   [[nodiscard]] std::error_code 508   [[nodiscard]] std::error_code
510   add_certificate_authority(std::string_view ca); 509   add_certificate_authority(std::string_view ca);
511   510  
512   /** Load CA certificates from a file. 511   /** Load CA certificates from a file.
513   512  
514   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
515   contain multiple concatenated PEM certificates. 514   contain multiple concatenated PEM certificates.
516   515  
517   @param filename Path to a PEM file containing CA certificates. 516   @param filename Path to a PEM file containing CA certificates.
518   517  
519   @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
520   certificates are decoded when the native context is first 519   certificates are decoded when the native context is first
521 - built. Malformed certificates are handled as described for 520 + built; malformed certificates surface as a handshake failure.
522 - `add_certificate_authority()`.  
523   521  
524   @par Example 522   @par Example
525   @par !example load_verify_file 523   @par !example load_verify_file
526   524  
527   @see add_certificate_authority 525   @see add_certificate_authority
528   @see add_verify_path 526   @see add_verify_path
529   */ 527   */
530   [[nodiscard]] std::error_code load_verify_file(std::string_view filename); 528   [[nodiscard]] std::error_code load_verify_file(std::string_view filename);
531   529  
532   /** Add a directory of CA certificates for verification. 530   /** Add a directory of CA certificates for verification.
533   531  
534   Adds a directory of CA certificates to the trust store. The 532   Adds a directory of CA certificates to the trust store. The
535   directory is applied when the native context is first built from 533   directory is applied when the native context is first built from
536   this context. 534   this context.
537   535  
538   The expected directory layout depends on the backend. OpenSSL 536   The expected directory layout depends on the backend. OpenSSL
539   performs on-demand lookups. Each certificate file must be named 537   performs on-demand lookups. Each certificate file must be named
540   by its subject-name hash, as generated by `openssl rehash` or 538   by its subject-name hash, as generated by `openssl rehash` or
541   `c_rehash`. WolfSSL loads every certificate file in the 539   `c_rehash`. WolfSSL loads every certificate file in the
542   directory. 540   directory.
543   541  
544   @param path Path to the directory of CA certificates. 542   @param path Path to the directory of CA certificates.
545   543  
546   @return Success. The path is recorded and applied when the native 544   @return Success. The path is recorded and applied when the native
547   context is built. A directory that cannot be read at that time is 545   context is built. A directory that cannot be read at that time is
548   skipped rather than reported here. 546   skipped rather than reported here.
549   547  
550   @par Example 548   @par Example
551   @par !example add_verify_path 549   @par !example add_verify_path
552   550  
553   @see load_verify_file 551   @see load_verify_file
554   @see set_default_verify_paths 552   @see set_default_verify_paths
555   */ 553   */
556   [[nodiscard]] std::error_code add_verify_path(std::string_view path); 554   [[nodiscard]] std::error_code add_verify_path(std::string_view path);
557   555  
558   /** Use the system default CA certificate store. 556   /** Use the system default CA certificate store.
559   557  
560 - Configures the context to use the backend's default trust store 558 + Configures the context to use the operating system's default
561 - for peer certificate verification. This is the 559 + trust store for peer certificate verification. This is the
562   recommended approach for HTTPS clients connecting to public 560   recommended approach for HTTPS clients connecting to public
563   servers. 561   servers.
564   562  
565   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
566   from this context. For a verified-safe client, combine this with 564   from this context. For a verified-safe client, combine this with
567   `set_verify_mode( tls_verify_mode::peer )` and, when connecting by 565   `set_verify_mode( tls_verify_mode::peer )` and, when connecting by
568   name, `tls_stream::set_hostname()`. 566   name, `tls_stream::set_hostname()`.
569   567  
570   @return Success. The request is recorded and applied when the 568   @return Success. The request is recorded and applied when the
571   native context is built. A system store that cannot be loaded at 569   native context is built. A system store that cannot be loaded at
572   that time is skipped rather than reported here. A context that 570   that time is skipped rather than reported here. A context that
573   must reject unverified peers should therefore also use 571   must reject unverified peers should therefore also use
574   `set_verify_mode( tls_verify_mode::peer )`. 572   `set_verify_mode( tls_verify_mode::peer )`.
575   573  
576 - @note OpenSSL reads the CA file and directory it was built with, 574 + @note The OpenSSL backend honors the `SSL_CERT_FILE` and
577 - or those named by `SSL_CERT_FILE` and `SSL_CERT_DIR`. It does 575 + `SSL_CERT_DIR` environment variables. The WolfSSL backend
578 - not read the macOS Keychain or the Windows Certificate Store. 576 + requires a build with `WOLFSSL_SYS_CA_CERTS`; without it the
579 - WolfSSL reads the platform store and requires a build with 577 + system store is unavailable and this call has no effect.
580 - `WOLFSSL_SYS_CA_CERTS`; without it this call has no effect.  
581   578  
582   @par Example 579   @par Example
583   @par !example set_default_verify_paths 580   @par !example set_default_verify_paths
584   581  
585   @see load_verify_file 582   @see load_verify_file
586   @see add_verify_path 583   @see add_verify_path
587   @see set_verify_mode 584   @see set_verify_mode
588   */ 585   */
589   [[nodiscard]] std::error_code set_default_verify_paths(); 586   [[nodiscard]] std::error_code set_default_verify_paths();
590   587  
591   // 588   //
592   // Protocol Configuration 589   // Protocol Configuration
593   // 590   //
594   591  
595   /** Set the minimum TLS protocol version. 592   /** Set the minimum TLS protocol version.
596   593  
597   Connections reject protocol versions older than this. 594   Connections reject protocol versions older than this.
598   The default allows TLS 1.2 and newer. 595   The default allows TLS 1.2 and newer.
599   596  
600   @param v The minimum protocol version to accept. 597   @param v The minimum protocol version to accept.
601   598  
602   @return Success. The version is recorded and applied when the 599   @return Success. The version is recorded and applied when the
603   native context is first built. 600   native context is first built.
604   601  
605   @par Example 602   @par Example
606   @par !example set_min_protocol_version 603   @par !example set_min_protocol_version
607   604  
608   @see set_max_protocol_version 605   @see set_max_protocol_version
609   */ 606   */
610   [[nodiscard]] std::error_code set_min_protocol_version(tls_version v); 607   [[nodiscard]] std::error_code set_min_protocol_version(tls_version v);
611   608  
612   /** Set the maximum TLS protocol version. 609   /** Set the maximum TLS protocol version.
613   610  
614   Connections do not negotiate protocol versions newer than this. 611   Connections do not negotiate protocol versions newer than this.
615   The default allows the newest supported version. 612   The default allows the newest supported version.
616   613  
617   @param v The maximum protocol version to accept. 614   @param v The maximum protocol version to accept.
618   615  
619   @return Success. The version is recorded and applied when the 616   @return Success. The version is recorded and applied when the
620   native context is first built. 617   native context is first built.
621   618  
622   @note On WolfSSL the ceiling is applied by selecting a 619   @note On WolfSSL the ceiling is applied by selecting a
623   version-specific method, because no native set-max API exists. An 620   version-specific method, because no native set-max API exists. An
624   invalid window, where the minimum exceeds the maximum, yields a 621   invalid window, where the minimum exceeds the maximum, yields a
625   context that fails the handshake. 622   context that fails the handshake.
626   623  
627   @see set_min_protocol_version 624   @see set_min_protocol_version
628   */ 625   */
629   [[nodiscard]] std::error_code set_max_protocol_version(tls_version v); 626   [[nodiscard]] std::error_code set_max_protocol_version(tls_version v);
630   627  
631   /** Set the allowed cipher suites. 628   /** Set the allowed cipher suites.
632   629  
633   Configures which cipher suites may be used for connections. 630   Configures which cipher suites may be used for connections.
634   The format is backend-specific but typically follows OpenSSL 631   The format is backend-specific but typically follows OpenSSL
635   cipher list syntax. 632   cipher list syntax.
636   633  
637   @param ciphers The cipher suite specification string. 634   @param ciphers The cipher suite specification string.
638   635  
639   @return Success. The string is recorded and applied when the 636   @return Success. The string is recorded and applied when the
640   native context is first built; an invalid cipher string 637   native context is first built; an invalid cipher string
641   surfaces as a handshake failure. 638   surfaces as a handshake failure.
642   639  
643   @par Example 640   @par Example
644   @par !example set_ciphersuites 641   @par !example set_ciphersuites
645   642  
646   @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
647   TLS 1.3, use @ref set_ciphersuites_tls13. 644   TLS 1.3, use @ref set_ciphersuites_tls13.
648   */ 645   */
649   [[nodiscard]] std::error_code set_ciphersuites(std::string_view ciphers); 646   [[nodiscard]] std::error_code set_ciphersuites(std::string_view ciphers);
650   647  
651   /** Set the allowed TLS 1.3 cipher suites. 648   /** Set the allowed TLS 1.3 cipher suites.
652   649  
653   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
654   separately from earlier versions. The format is a colon-separated 651   separately from earlier versions. The format is a colon-separated
655   list of TLS 1.3 suite names. 652   list of TLS 1.3 suite names.
656   653  
657   @param ciphers The TLS 1.3 cipher suite list. 654   @param ciphers The TLS 1.3 cipher suite list.
658   655  
659   @return Success. The string is recorded and applied when the 656   @return Success. The string is recorded and applied when the
660   native context is first built; an invalid cipher string 657   native context is first built; an invalid cipher string
661   surfaces as a handshake failure. 658   surfaces as a handshake failure.
662   659  
663   @par Example 660   @par Example
664   @par !example set_ciphersuites_tls13 661   @par !example set_ciphersuites_tls13
665   662  
666   @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
667   single cipher list; this call and @ref set_ciphersuites are 664   single cipher list; this call and @ref set_ciphersuites are
668   merged into one list. 665   merged into one list.
669   666  
670   @see set_ciphersuites 667   @see set_ciphersuites
671   */ 668   */
672   [[nodiscard]] std::error_code 669   [[nodiscard]] std::error_code
673   set_ciphersuites_tls13(std::string_view ciphers); 670   set_ciphersuites_tls13(std::string_view ciphers);
674   671  
675   /** Set the ALPN protocol list. 672   /** Set the ALPN protocol list.
676   673  
677   Configures Application-Layer Protocol Negotiation (ALPN) for 674   Configures Application-Layer Protocol Negotiation (ALPN) for
678   the connection. ALPN is used to negotiate which application 675   the connection. ALPN is used to negotiate which application
679   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,
680   "http/1.1" for HTTP/1.1). 677   "http/1.1" for HTTP/1.1).
681   678  
682   The protocols are tried in preference order (first = highest). 679   The protocols are tried in preference order (first = highest).
683   680  
684   @param protocols Ordered list of protocol identifiers. 681   @param protocols Ordered list of protocol identifiers.
685   682  
686   @return Success, or an error if ALPN configuration fails. 683   @return Success, or an error if ALPN configuration fails.
687   684  
688   @note Read the negotiated protocol after the handshake via 685   @note Read the negotiated protocol after the handshake via
689   @ref tls_stream::alpn_protocol. On WolfSSL, ALPN requires a 686   @ref tls_stream::alpn_protocol. On WolfSSL, ALPN requires a
690   build with `HAVE_ALPN`; without it, offering protocols fails 687   build with `HAVE_ALPN`; without it, offering protocols fails
691   the handshake with `std::errc::function_not_supported` rather 688   the handshake with `std::errc::function_not_supported` rather
692   than negotiate nothing silently. 689   than negotiate nothing silently.
693   690  
694   @par Example 691   @par Example
695   @par !example set_alpn 692   @par !example set_alpn
696   */ 693   */
697   [[nodiscard]] std::error_code 694   [[nodiscard]] std::error_code
698   set_alpn(std::initializer_list<std::string_view> protocols); 695   set_alpn(std::initializer_list<std::string_view> protocols);
699   696  
700   // 697   //
701   // Certificate Verification 698   // Certificate Verification
702   // 699   //
703   700  
704   /** Set the peer certificate verification mode. 701   /** Set the peer certificate verification mode.
705   702  
706   Controls whether and how peer certificates are verified during 703   Controls whether and how peer certificates are verified during
707   the TLS handshake. 704   the TLS handshake.
708   705  
709   @param mode The verification mode to use. 706   @param mode The verification mode to use.
710   707  
711   @return Success. The mode is recorded and applied when the native 708   @return Success. The mode is recorded and applied when the native
712   context is first built. 709   context is first built.
713   710  
714   @par Example 711   @par Example
715   @par !example set_verify_mode 712   @par !example set_verify_mode
716   713  
717   @see tls_verify_mode 714   @see tls_verify_mode
718   */ 715   */
719   [[nodiscard]] std::error_code set_verify_mode(tls_verify_mode mode); 716   [[nodiscard]] std::error_code set_verify_mode(tls_verify_mode mode);
720   717  
721   /** Set the maximum certificate chain verification depth. 718   /** Set the maximum certificate chain verification depth.
722   719  
723   Limits how many intermediate certificates can appear between 720   Limits how many intermediate certificates can appear between
724   the peer certificate and a trusted root. The default is 721   the peer certificate and a trusted root. The default is
725   typically 100, which is sufficient for most certificate chains. 722   typically 100, which is sufficient for most certificate chains.
726   723  
727   @param depth Maximum number of intermediate certificates allowed. 724   @param depth Maximum number of intermediate certificates allowed.
728   725  
729   @return Success. The depth is recorded and applied when the native 726   @return Success. The depth is recorded and applied when the native
730   context is first built. 727   context is first built.
731   728  
732   @par Example 729   @par Example
733   @par !example set_verify_depth 730   @par !example set_verify_depth
734   */ 731   */
735   [[nodiscard]] std::error_code set_verify_depth(int depth); 732   [[nodiscard]] std::error_code set_verify_depth(int depth);
736   733  
737   /** Set a custom certificate verification callback. 734   /** Set a custom certificate verification callback.
738   735  
739   Installs a callback that is invoked during certificate chain 736   Installs a callback that is invoked during certificate chain
740   verification. The callback can perform additional validation 737   verification. The callback can perform additional validation
741   beyond the standard checks and can override verification 738   beyond the standard checks and can override verification
742   results. 739   results.
743   740  
744   The callback receives the built-in verification result so far and 741   The callback receives the built-in verification result so far and
745   a `verify_context` describing the certificate being verified. Return 742   a `verify_context` describing the certificate being verified. Return
746   `true` to accept the certificate, `false` to reject. Inspect the 743   `true` to accept the certificate, `false` to reject. Inspect the
747   certificate portably via `verify_context::certificate()` (its DER 744   certificate portably via `verify_context::certificate()` (its DER
748   encoding) — for example to pin a specific certificate. 745   encoding) — for example to pin a specific certificate.
749   746  
750   @par Backend Support 747   @par Backend Support
751   748  
752   The exact set of certificates the callback sees differs by backend: 749   The exact set of certificates the callback sees differs by backend:
753   750  
754   - OpenSSL: the callback runs once per certificate in the chain, 751   - OpenSSL: the callback runs once per certificate in the chain,
755   including certificates that passed the built-in checks. It can 752   including certificates that passed the built-in checks. It can
756   therefore relax verification by returning `true` for a 753   therefore relax verification by returning `true` for a
757   certificate the library rejected. It can also tighten 754   certificate the library rejected. It can also tighten
758   verification by returning `false` for a certificate the library 755   verification by returning `false` for a certificate the library
759   accepted, as pinning does. 756   accepted, as pinning does.
760   - WolfSSL built with `WOLFSSL_ALWAYS_VERIFY_CB` (implied by 757   - WolfSSL built with `WOLFSSL_ALWAYS_VERIFY_CB` (implied by
761   `--enable-opensslextra`): same as OpenSSL. 758   `--enable-opensslextra`): same as OpenSSL.
762   - WolfSSL without that option: the library invokes the callback 759   - WolfSSL without that option: the library invokes the callback
763   only on verification *failure*, so it cannot be honored on a 760   only on verification *failure*, so it cannot be honored on a
764   successful handshake. Silently ignoring a verification-tightening 761   successful handshake. Silently ignoring a verification-tightening
765   callback would fail open. On such a build, a context that carries 762   callback would fail open. On such a build, a context that carries
766   a callback instead **fails the handshake** with 763   a callback instead **fails the handshake** with
767   `std::errc::function_not_supported`. Rebuild 764   `std::errc::function_not_supported`. Rebuild
768   WolfSSL with `WOLFSSL_ALWAYS_VERIFY_CB`, or omit the callback. 765   WolfSSL with `WOLFSSL_ALWAYS_VERIFY_CB`, or omit the callback.
769   766  
770   @tparam Callback A callable with signature 767   @tparam Callback A callable with signature
771   `bool( bool preverified, verify_context& ctx )`. 768   `bool( bool preverified, verify_context& ctx )`.
772   769  
773   @param callback The verification callback. Recorded here and 770   @param callback The verification callback. Recorded here and
774   applied during the handshake; on a WolfSSL build that 771   applied during the handshake; on a WolfSSL build that
775   cannot honor it, the handshake fails with 772   cannot honor it, the handshake fails with
776   `std::errc::function_not_supported` (see Backend Support). 773   `std::errc::function_not_supported` (see Backend Support).
777   774  
778   @par Example 775   @par Example
779   @par !example set_verify_callback 776   @par !example set_verify_callback
780   777  
781   @see verify_context 778   @see verify_context
782   @see set_verify_mode 779   @see set_verify_mode
783   */ 780   */
784   template<typename Callback> 781   template<typename Callback>
785   void set_verify_callback(Callback callback); 782   void set_verify_callback(Callback callback);
786   783  
787   /** Set a callback for Server Name Indication (SNI). 784   /** Set a callback for Server Name Indication (SNI).
788   785  
789   For server connections, this callback is invoked during the TLS 786   For server connections, this callback is invoked during the TLS
790   handshake when a client sends an SNI extension. The callback 787   handshake when a client sends an SNI extension. The callback
791   receives the requested hostname and can accept or reject the 788   receives the requested hostname and can accept or reject the
792   connection. 789   connection.
793   790  
794   @tparam Callback A callable with signature 791   @tparam Callback A callable with signature
795   `bool( std::string_view hostname )`. 792   `bool( std::string_view hostname )`.
796   793  
797   @param callback The SNI callback. Return `true` to accept the 794   @param callback The SNI callback. Return `true` to accept the
798   connection or `false` to reject it with an alert. 795   connection or `false` to reject it with an alert.
799   796  
800   @par Example 797   @par Example
801   @par !example set_servername_callback 798   @par !example set_servername_callback
802   799  
803   @note For virtual hosting with different certificates per hostname, 800   @note For virtual hosting with different certificates per hostname,
804   create separate contexts and select the appropriate one before 801   create separate contexts and select the appropriate one before
805   creating the TLS stream. 802   creating the TLS stream.
806   803  
807   @see tls_stream::set_hostname 804   @see tls_stream::set_hostname
808   */ 805   */
809   template<typename Callback> 806   template<typename Callback>
810   void set_servername_callback(Callback callback); 807   void set_servername_callback(Callback callback);
811   808  
812   private: 809   private:
813   void set_servername_callback_impl( 810   void set_servername_callback_impl(
814   std::function<bool(std::string_view)> callback); 811   std::function<bool(std::string_view)> callback);
815   812  
816   void set_password_callback_impl( 813   void set_password_callback_impl(
817   std::function<std::string(std::size_t, tls_password_purpose)> callback); 814   std::function<std::string(std::size_t, tls_password_purpose)> callback);
818   815  
819   void set_verify_callback_impl( 816   void set_verify_callback_impl(
820   std::function<bool(bool, verify_context&)> callback); 817   std::function<bool(bool, verify_context&)> callback);
821   818  
822   public: 819   public:
823   // 820   //
824   // Revocation Checking 821   // Revocation Checking
825   // 822   //
826   823  
827   /** Add a Certificate Revocation List from memory. 824   /** Add a Certificate Revocation List from memory.
828   825  
829   Adds a CRL to the verification store for checking whether 826   Adds a CRL to the verification store for checking whether
830   certificates are revoked. CRLs are typically fetched 827   certificates are revoked. CRLs are typically fetched
831   from the URLs in a certificate's CRL Distribution Points 828   from the URLs in a certificate's CRL Distribution Points
832   extension. 829   extension.
833   830  
834   @param crl The CRL data in DER or PEM format. 831   @param crl The CRL data in DER or PEM format.
835   832  
836   @return Success. The CRL is recorded and decoded when the native 833   @return Success. The CRL is recorded and decoded when the native
837   context is first built; a malformed CRL surfaces as a 834   context is first built; a malformed CRL surfaces as a
838   handshake failure. 835   handshake failure.
839   836  
840   @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
841   @ref set_revocation_policy. On WolfSSL, CRL checking requires a 838   @ref set_revocation_policy. On WolfSSL, CRL checking requires a
842 - build with `HAVE_CRL`; without it, a revocation policy 839 + build with `HAVE_CRL`; without it, supplying a CRL or a
843 - other than `disabled` fails the handshake with 840 + revocation policy fails the handshake with
844   `std::errc::function_not_supported`. 841   `std::errc::function_not_supported`.
845   842  
846   @see add_crl_file 843   @see add_crl_file
847   @see set_revocation_policy 844   @see set_revocation_policy
848   */ 845   */
849   [[nodiscard]] std::error_code add_crl(std::string_view crl); 846   [[nodiscard]] std::error_code add_crl(std::string_view crl);
850   847  
851   /** Add a Certificate Revocation List from a file. 848   /** Add a Certificate Revocation List from a file.
852   849  
853   Adds a CRL to the verification store for checking whether 850   Adds a CRL to the verification store for checking whether
854   certificates are revoked. 851   certificates are revoked.
855   852  
856   @param filename Path to a CRL file (DER or PEM format). 853   @param filename Path to a CRL file (DER or PEM format).
857   854  
858   @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
859   CRL is decoded when the native context is first built; a 856   CRL is decoded when the native context is first built; a
860   malformed CRL surfaces as a handshake failure. 857   malformed CRL surfaces as a handshake failure.
861   858  
862   @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
863   @ref set_revocation_policy (WolfSSL requires a `HAVE_CRL` 860   @ref set_revocation_policy (WolfSSL requires a `HAVE_CRL`
864   build). 861   build).
865   862  
866   @par Example 863   @par Example
867   @par !example add_crl_file 864   @par !example add_crl_file
868   865  
869   @see add_crl 866   @see add_crl
870   @see set_revocation_policy 867   @see set_revocation_policy
871   */ 868   */
872   [[nodiscard]] std::error_code add_crl_file(std::string_view filename); 869   [[nodiscard]] std::error_code add_crl_file(std::string_view filename);
873   870  
874   /** Set the certificate revocation checking policy. 871   /** Set the certificate revocation checking policy.
875   872  
876   Controls how certificate revocation status is checked during 873   Controls how certificate revocation status is checked during
877   verification via CRLs. 874   verification via CRLs.
878   875  
879   @param policy The revocation checking policy. 876   @param policy The revocation checking policy.
880   877  
881   @par Example 878   @par Example
882   @par !example set_revocation_policy 879   @par !example set_revocation_policy
883   880  
884   @note Revocation is checked via CRLs supplied with @ref add_crl / 881   @note Revocation is checked via CRLs supplied with @ref add_crl /
885   @ref add_crl_file. `soft_fail` accepts a certificate whose 882   @ref add_crl_file. `soft_fail` accepts a certificate whose
886   status cannot be determined (missing/expired CRL) but rejects 883   status cannot be determined (missing/expired CRL) but rejects
887   one that is actually revoked; `hard_fail` also rejects unknown 884   one that is actually revoked; `hard_fail` also rejects unknown
888   status. OCSP-based revocation is not available (see the TLS 885   status. OCSP-based revocation is not available (see the TLS
889   guide). On WolfSSL a non-disabled policy requires a `HAVE_CRL` 886   guide). On WolfSSL a non-disabled policy requires a `HAVE_CRL`
890   build, else the handshake fails with 887   build, else the handshake fails with
891   `std::errc::function_not_supported`. 888   `std::errc::function_not_supported`.
892   889  
893   @see tls_revocation_policy 890   @see tls_revocation_policy
894   @see add_crl 891   @see add_crl
895   */ 892   */
896   void set_revocation_policy(tls_revocation_policy policy); 893   void set_revocation_policy(tls_revocation_policy policy);
897   894  
898   // 895   //
899   // Password Handling 896   // Password Handling
900   // 897   //
901   898  
902   /** Set the password callback for encrypted keys. 899   /** Set the password callback for encrypted keys.
903   900  
904   Installs a callback that provides passwords for encrypted 901   Installs a callback that provides passwords for encrypted
905   private keys and PKCS#12 files. The callback is invoked when 902   private keys and PKCS#12 files. The callback is invoked when
906   loading encrypted key material. 903   loading encrypted key material.
907   904  
908   @tparam Callback A callable with signature 905   @tparam Callback A callable with signature
909   `std::string( std::size_t max_length, tls_password_purpose purpose )`. 906   `std::string( std::size_t max_length, tls_password_purpose purpose )`.
910   907  
911   @param callback The password callback. It receives the maximum 908   @param callback The password callback. It receives the maximum
912   password length and the purpose (reading or writing), and 909   password length and the purpose (reading or writing), and
913   returns the password string. 910   returns the password string.
914   911  
915   @par Example 912   @par Example
916   @par !example set_password_callback 913   @par !example set_password_callback
917   914  
918   @see tls_password_purpose 915   @see tls_password_purpose
919   */ 916   */
920   template<typename Callback> 917   template<typename Callback>
921   void set_password_callback(Callback callback); 918   void set_password_callback(Callback callback);
922   }; 919   };
923   #ifdef _MSC_VER 920   #ifdef _MSC_VER
924   #pragma warning(pop) 921   #pragma warning(pop)
925   #endif 922   #endif
926   923  
927   template<typename Callback> 924   template<typename Callback>
928   void 925   void
HITCBC 929   1 tls_context::set_servername_callback(Callback callback) 926   1 tls_context::set_servername_callback(Callback callback)
930   { 927   {
HITCBC 931   1 set_servername_callback_impl(std::move(callback)); 928   1 set_servername_callback_impl(std::move(callback));
HITCBC 932   1 } 929   1 }
933   930  
934   template<typename Callback> 931   template<typename Callback>
935   void 932   void
HITCBC 936   4 tls_context::set_password_callback(Callback callback) 933   4 tls_context::set_password_callback(Callback callback)
937   { 934   {
HITCBC 938   4 set_password_callback_impl(std::move(callback)); 935   4 set_password_callback_impl(std::move(callback));
HITCBC 939   4 } 936   4 }
940   937  
941   template<typename Callback> 938   template<typename Callback>
942   void 939   void
HITCBC 943   2 tls_context::set_verify_callback(Callback callback) 940   2 tls_context::set_verify_callback(Callback callback)
944   { 941   {
HITCBC 945   2 set_verify_callback_impl(std::move(callback)); 942   2 set_verify_callback_impl(std::move(callback));
HITCBC 946   2 } 943   2 }
947   944  
948   } // namespace boost::corosio 945   } // namespace boost::corosio
949   946  
950   #endif 947   #endif