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