. /include/boost/corosio /tls_stream.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   // Copyright (c) 2026 Steve Gerbino 4   // Copyright (c) 2026 Steve Gerbino
5   // 5   //
6   // Distributed under the Boost Software License, Version 1.0. (See accompanying 6   // Distributed under the Boost Software License, Version 1.0. (See accompanying
7   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 7   // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
8   // 8   //
9   // Official repository: https://github.com/cppalliance/corosio 9   // Official repository: https://github.com/cppalliance/corosio
10   // 10   //
11   11  
12   #ifndef BOOST_COROSIO_TLS_STREAM_HPP 12   #ifndef BOOST_COROSIO_TLS_STREAM_HPP
13   #define BOOST_COROSIO_TLS_STREAM_HPP 13   #define BOOST_COROSIO_TLS_STREAM_HPP
14   14  
15   #include <boost/corosio/detail/config.hpp> 15   #include <boost/corosio/detail/config.hpp>
16   #include <boost/capy/buffers.hpp> 16   #include <boost/capy/buffers.hpp>
17   #include <boost/capy/detail/buffer_array.hpp> 17   #include <boost/capy/detail/buffer_array.hpp>
18   #include <boost/capy/io/any_stream.hpp> 18   #include <boost/capy/io/any_stream.hpp>
19   #include <boost/capy/io_task.hpp> 19   #include <boost/capy/io_task.hpp>
20   20  
21   #include <cstddef> 21   #include <cstddef>
22   #include <string_view> 22   #include <string_view>
23   23  
24   namespace boost::corosio { 24   namespace boost::corosio {
25   25  
26   /** TLS handshake role. 26   /** TLS handshake role.
27   27  
28   Specifies whether to perform the TLS handshake as a client or server. 28   Specifies whether to perform the TLS handshake as a client or server.
29   29  
30   @see tls_stream::handshake 30   @see tls_stream::handshake
31   */ 31   */
32   enum class tls_role 32   enum class tls_role
33   { 33   {
34   /// Perform handshake as the connecting client. 34   /// Perform handshake as the connecting client.
35   client, 35   client,
36   36  
37   /// Perform handshake as the accepting server. 37   /// Perform handshake as the accepting server.
38   server 38   server
39   }; 39   };
40   40  
41   /** Reads, writes, and manages the handshake lifecycle of a TLS 41   /** Reads, writes, and manages the handshake lifecycle of a TLS
42   session over an underlying stream. 42   session over an underlying stream.
43   43  
44   This class provides a runtime-polymorphic interface for TLS 44   This class provides a runtime-polymorphic interface for TLS
45   implementations. Derived classes (`openssl_stream`, `wolfssl_stream`) 45   implementations. Derived classes (`openssl_stream`, `wolfssl_stream`)
46   implement the virtual functions to provide backend-specific 46   implement the virtual functions to provide backend-specific
47   TLS functionality. 47   TLS functionality.
48   48  
49   An @ref io_stream represents OS-level I/O completed by the kernel. 49   An @ref io_stream represents OS-level I/O completed by the kernel.
50   TLS streams are coroutine-based instead: their operations are 50   TLS streams are coroutine-based instead: their operations are
51   coroutines that orchestrate sub-operations on the underlying stream. 51   coroutines that orchestrate sub-operations on the underlying stream.
52   52  
53   The non-virtual template wrappers (`read_some`, `write_some`) 53   The non-virtual template wrappers (`read_some`, `write_some`)
54   satisfy the `capy::Stream` concept, enabling TLS streams to 54   satisfy the `capy::Stream` concept, enabling TLS streams to
55   be used anywhere a Stream is expected. 55   be used anywhere a Stream is expected.
56   56  
57   @par Thread Safety 57   @par Thread Safety
58   Distinct objects: Safe.@n 58   Distinct objects: Safe.@n
59   Shared objects: Unsafe, with one exception: one read operation and 59   Shared objects: Unsafe, with one exception: one read operation and
60   one write operation may be in flight simultaneously. `shutdown()` 60   one write operation may be in flight simultaneously. `shutdown()`
61   may overlap a pending read. On a multi-threaded execution context, 61   may overlap a pending read. On a multi-threaded execution context,
62   all operations on one stream must run within the same 62   all operations on one stream must run within the same
63   `capy::strand`, or must otherwise never run concurrently. A 63   `capy::strand`, or must otherwise never run concurrently. A
64   single-threaded context needs no strand. 64   single-threaded context needs no strand.
65   65  
66   @see openssl_stream, wolfssl_stream 66   @see openssl_stream, wolfssl_stream
67   */ 67   */
68   class BOOST_COROSIO_DECL tls_stream 68   class BOOST_COROSIO_DECL tls_stream
69   { 69   {
70   public: 70   public:
71   /// Destroy the TLS stream. 71   /// Destroy the TLS stream.
72   virtual ~tls_stream() = default; 72   virtual ~tls_stream() = default;
73   73  
74   /// Copy construction is disabled; copying a stream would slice the derived session. 74   /// Copy construction is disabled; copying a stream would slice the derived session.
75   tls_stream(tls_stream const&) = delete; 75   tls_stream(tls_stream const&) = delete;
76   /// Copy assignment is disabled; copying a stream would slice the derived session. 76   /// Copy assignment is disabled; copying a stream would slice the derived session.
77   tls_stream& operator=(tls_stream const&) = delete; 77   tls_stream& operator=(tls_stream const&) = delete;
78   78  
79   /** Initiate an asynchronous read operation. 79   /** Initiate an asynchronous read operation.
80   80  
81   Reads decrypted data into the provided buffer sequence. The 81   Reads decrypted data into the provided buffer sequence. The
82   operation completes when it reads at least one byte, 82   operation completes when it reads at least one byte,
83   or an error occurs. 83   or an error occurs.
84   84  
85   This non-virtual template wrapper satisfies the `capy::Stream` 85   This non-virtual template wrapper satisfies the `capy::Stream`
86   concept by delegating to the virtual `do_read_some`. 86   concept by delegating to the virtual `do_read_some`.
87   87  
88   @par Thread Safety 88   @par Thread Safety
89   May run concurrently with one operation in the other 89   May run concurrently with one operation in the other
90   direction, subject to the class-level threading contract. 90   direction, subject to the class-level threading contract.
91   Two concurrent operations in the same direction are 91   Two concurrent operations in the same direction are
92   undefined. 92   undefined.
93   93  
94   @param buffers The buffer sequence to read data into. 94   @param buffers The buffer sequence to read data into.
95   95  
96   @return An awaitable yielding `(error_code,std::size_t)`. 96   @return An awaitable yielding `(error_code,std::size_t)`.
97   */ 97   */
98   template<capy::MutableBufferSequence Buffers> 98   template<capy::MutableBufferSequence Buffers>
MISUBC 99   ✗ [[nodiscard]] auto read_some(Buffers const& buffers) 99   ✗ [[nodiscard]] auto read_some(Buffers const& buffers)
100   { 100   {
MISUBC 101   ✗ return do_read_some(buffers); 101   ✗ return do_read_some(buffers);
102   } 102   }
103   103  
104   /** Initiate an asynchronous write operation. 104   /** Initiate an asynchronous write operation.
105   105  
106   Encrypts and writes data from the provided buffer sequence. 106   Encrypts and writes data from the provided buffer sequence.
107   The operation completes when it writes at least one byte, 107   The operation completes when it writes at least one byte,
108   or an error occurs. 108   or an error occurs.
109   109  
110   This non-virtual template wrapper satisfies the `capy::Stream` 110   This non-virtual template wrapper satisfies the `capy::Stream`
111   concept by delegating to the virtual `do_write_some`. 111   concept by delegating to the virtual `do_write_some`.
112   112  
113   @par Thread Safety 113   @par Thread Safety
114   May run concurrently with one operation in the other 114   May run concurrently with one operation in the other
115   direction, subject to the class-level threading contract. 115   direction, subject to the class-level threading contract.
116   Two concurrent operations in the same direction are 116   Two concurrent operations in the same direction are
117   undefined. 117   undefined.
118   118  
119   @param buffers The buffer sequence containing data to write. 119   @param buffers The buffer sequence containing data to write.
120   120  
121   @return An awaitable yielding `(error_code,std::size_t)`. 121   @return An awaitable yielding `(error_code,std::size_t)`.
122   */ 122   */
123   template<capy::ConstBufferSequence Buffers> 123   template<capy::ConstBufferSequence Buffers>
MISUBC 124   ✗ [[nodiscard]] auto write_some(Buffers const& buffers) 124   ✗ [[nodiscard]] auto write_some(Buffers const& buffers)
125   { 125   {
MISUBC 126   ✗ return do_write_some(buffers); 126   ✗ return do_write_some(buffers);
127   } 127   }
128   128  
129   /** Asynchronously perform the TLS handshake. 129   /** Asynchronously perform the TLS handshake.
130   130  
131   Initiates the TLS handshake process. For client connections, 131   Initiates the TLS handshake process. For client connections,
132   this sends the ClientHello and processes the server's response. 132   this sends the ClientHello and processes the server's response.
133   For server connections, this waits for the ClientHello and 133   For server connections, this waits for the ClientHello and
134   sends the server's response. 134   sends the server's response.
135   135  
136   A handshake attempt consumes the stream state, whether it 136   A handshake attempt consumes the stream state, whether it
137   succeeds or not. A subsequent call behaves as if `reset()` ran 137   succeeds or not. A subsequent call behaves as if `reset()` ran
138   first, and performs a fresh handshake using the current 138   first, and performs a fresh handshake using the current
139   configuration. 139   configuration.
140   140  
141   @pre The underlying stream must be connected. No other TLS 141   @pre The underlying stream must be connected. No other TLS
142   operation may be in progress on this stream. 142   operation may be in progress on this stream.
143   143  
144   @param role The handshake role, client or server. 144   @param role The handshake role, client or server.
145   145  
146   @return An awaitable yielding `(error_code)`. 146   @return An awaitable yielding `(error_code)`.
147   */ 147   */
148   [[nodiscard]] virtual capy::io_task<> handshake(tls_role role) = 0; 148   [[nodiscard]] virtual capy::io_task<> handshake(tls_role role) = 0;
149   149  
150   /** Asynchronously perform a graceful TLS shutdown. 150   /** Asynchronously perform a graceful TLS shutdown.
151   151  
152   Initiates the TLS shutdown sequence by sending a close_notify 152   Initiates the TLS shutdown sequence by sending a close_notify
153   alert and waiting for the peer's close_notify response. 153   alert and waiting for the peer's close_notify response.
154   154  
155   @pre A handshake must have completed successfully. May overlap 155   @pre A handshake must have completed successfully. May overlap
156   a pending read. No concurrent write may be in progress. 156   a pending read. No concurrent write may be in progress.
157   157  
158   @par Postconditions 158   @par Postconditions
159   If the transport ends before the peer's close_notify arrives, 159   If the transport ends before the peer's close_notify arrives,
160   the result is `capy::error::stream_truncated`, not success. An 160   the result is `capy::error::stream_truncated`, not success. An
161   unannounced close is indistinguishable from a truncation attack, 161   unannounced close is indistinguishable from a truncation attack,
162   so it must not be reported as a clean shutdown. A shutdown 162   so it must not be reported as a clean shutdown. A shutdown
163   stopped mid-flight reports canceled. Any other transport 163   stopped mid-flight reports canceled. Any other transport
164   error propagates unchanged. 164   error propagates unchanged.
165   165  
166   @return An awaitable yielding `(error_code)`. 166   @return An awaitable yielding `(error_code)`.
167   */ 167   */
168   [[nodiscard]] virtual capy::io_task<> shutdown() = 0; 168   [[nodiscard]] virtual capy::io_task<> shutdown() = 0;
169   169  
170   /** Reset TLS session state for reuse. 170   /** Reset TLS session state for reuse.
171   171  
172   Releases TLS session state including session keys and peer 172   Releases TLS session state including session keys and peer
173   certificates, returning the stream to a state where 173   certificates, returning the stream to a state where
174   `handshake()` can be called again. Internal memory 174   `handshake()` can be called again. Internal memory
175   allocations (I/O buffers) are preserved. 175   allocations (I/O buffers) are preserved.
176   176  
177   Calling `handshake()` on a previously-used stream 177   Calling `handshake()` on a previously-used stream
178   implicitly performs a reset first, so explicit calls 178   implicitly performs a reset first, so explicit calls
179   are only needed to eagerly release session state. 179   are only needed to eagerly release session state.
180   180  
181   @pre No TLS operation (handshake, read, write, shutdown) is 181   @pre No TLS operation (handshake, read, write, shutdown) is
182   in progress. 182   in progress.
183   183  
184   @par Thread Safety 184   @par Thread Safety
185   Not thread safe. The caller must ensure no concurrent 185   Not thread safe. The caller must ensure no concurrent
186   operations are in progress on this stream. 186   operations are in progress on this stream.
187   187  
188   @note If called mid-session before `shutdown()`, pending 188   @note If called mid-session before `shutdown()`, pending
189   TLS data is discarded and the peer observes a 189   TLS data is discarded and the peer observes a
190   truncated stream. 190   truncated stream.
191   */ 191   */
192   virtual void reset() = 0; 192   virtual void reset() = 0;
193   193  
194   /** Set the peer hostname for SNI and certificate verification. 194   /** Set the peer hostname for SNI and certificate verification.
195   195  
196   Configures the hostname sent in the TLS Server Name 196   Configures the hostname sent in the TLS Server Name
197   Indication extension and matched against the peer 197   Indication extension and matched against the peer
198   certificate during verification. The value takes effect 198   certificate during verification. The value takes effect
199   at the next `handshake()`; an established session is not 199   at the next `handshake()`; an established session is not
200   affected. It persists across `reset()`, so a stream reused 200   affected. It persists across `reset()`, so a stream reused
201   to reach a different host must set the new name before 201   to reach a different host must set the new name before
202   handshaking again. 202   handshaking again.
203   203  
204   An empty hostname (the default) disables SNI and hostname 204   An empty hostname (the default) disables SNI and hostname
205   verification. 205   verification.
206   206  
207   If `hostname` is an IP literal (IPv4 or IPv6), it is matched 207   If `hostname` is an IP literal (IPv4 or IPv6), it is matched
208   against the certificate's iPAddress entries instead of its DNS 208   against the certificate's iPAddress entries instead of its DNS
209   names. No SNI is sent, because RFC 6066 excludes literals. 209   names. No SNI is sent, because RFC 6066 excludes literals.
210   A backend build that cannot match iPAddress entries fails the 210   A backend build that cannot match iPAddress entries fails the
211   handshake with `std::errc::function_not_supported` rather 211   handshake with `std::errc::function_not_supported` rather
212   than skip verification. 212   than skip verification.
213   213  
214   @par Postconditions 214   @par Postconditions
215   The next `handshake()` uses `hostname` for SNI and 215   The next `handshake()` uses `hostname` for SNI and
216   certificate verification, or neither if it is empty. 216   certificate verification, or neither if it is empty.
217   217  
218   @note The hostname is used for client handshakes only; 218   @note The hostname is used for client handshakes only;
219   it is ignored when handshaking as a server. 219   it is ignored when handshaking as a server.
220   220  
221   @param hostname The peer hostname, or empty to disable. 221   @param hostname The peer hostname, or empty to disable.
222   */ 222   */
223   virtual void set_hostname(std::string_view hostname) = 0; 223   virtual void set_hostname(std::string_view hostname) = 0;
224   224  
225   /** Return a reference to the underlying stream. 225   /** Return a reference to the underlying stream.
226   226  
227   Provides access to the type-erased underlying stream for 227   Provides access to the type-erased underlying stream for
228   operations like cancellation or accessing native handles. 228   operations like cancellation or accessing native handles.
229   229  
230   @warning Do not reseat (assign to) the returned reference. 230   @warning Do not reseat (assign to) the returned reference.
231   The TLS implementation holds internal state bound to 231   The TLS implementation holds internal state bound to
232   the original stream. Replacing it causes undefined 232   the original stream. Replacing it causes undefined
233   behavior. 233   behavior.
234   234  
235   @return Reference to the wrapped stream. 235   @return Reference to the wrapped stream.
236   */ 236   */
237   virtual capy::any_stream& next_layer() noexcept = 0; 237   virtual capy::any_stream& next_layer() noexcept = 0;
238   238  
239   /** Return a const reference to the underlying stream. 239   /** Return a const reference to the underlying stream.
240   240  
241   @return Const reference to the wrapped stream. 241   @return Const reference to the wrapped stream.
242   */ 242   */
243   virtual capy::any_stream const& next_layer() const noexcept = 0; 243   virtual capy::any_stream const& next_layer() const noexcept = 0;
244   244  
245   /** Return the name of the TLS backend. 245   /** Return the name of the TLS backend.
246   246  
247   @return A string identifying the TLS implementation, 247   @return A string identifying the TLS implementation,
248   such as "openssl" or "wolfssl". 248   such as "openssl" or "wolfssl".
249   */ 249   */
250   virtual std::string_view name() const noexcept = 0; 250   virtual std::string_view name() const noexcept = 0;
251   251  
252   /** Return the ALPN protocol negotiated during the handshake. 252   /** Return the ALPN protocol negotiated during the handshake.
253   253  
254   Application-Layer Protocol Negotiation selects a single 254   Application-Layer Protocol Negotiation selects a single
255   application protocol (for example `"h2"` or `"http/1.1"`) 255   application protocol (for example `"h2"` or `"http/1.1"`)
256   during the TLS handshake, from the list supplied via 256   during the TLS handshake, from the list supplied via
257   @ref tls_context::set_alpn. 257   @ref tls_context::set_alpn.
258   258  
259   @return The negotiated protocol, or an empty view. It is empty 259   @return The negotiated protocol, or an empty view. It is empty
260   if no protocol was negotiated or ALPN was not offered. It is 260   if no protocol was negotiated or ALPN was not offered. It is
261   also empty if the handshake has not completed, or if the build 261   also empty if the handshake has not completed, or if the build
262   lacks ALPN support. 262   lacks ALPN support.
263   263  
264   @par Thread Safety 264   @par Thread Safety
265   Safe to call after the handshake completes; not safe to call 265   Safe to call after the handshake completes; not safe to call
266   concurrently with a handshake or reset. 266   concurrently with a handshake or reset.
267   */ 267   */
268   virtual std::string_view alpn_protocol() const noexcept 268   virtual std::string_view alpn_protocol() const noexcept
269   { 269   {
270   return {}; 270   return {};
271   } // LCOV_EXCL_LINE every concrete stream overrides this; the base default is never called 271   } // LCOV_EXCL_LINE every concrete stream overrides this; the base default is never called
272   272  
273   protected: 273   protected:
274   /// Default construct; a derived class supplies the session. 274   /// Default construct; a derived class supplies the session.
275   tls_stream() = default; 275   tls_stream() = default;
276   276  
277   /** Perform the backend-specific decrypted read. 277   /** Perform the backend-specific decrypted read.
278   278  
279   Derived classes override this to perform TLS decryption 279   Derived classes override this to perform TLS decryption
280   and read operations. 280   and read operations.
281   281  
282   @param buffers Buffer sequence to read into. 282   @param buffers Buffer sequence to read into.
283   283  
284   @return An awaitable yielding `(error_code,std::size_t)`. 284   @return An awaitable yielding `(error_code,std::size_t)`.
285   */ 285   */
286   virtual capy::io_task<std::size_t> do_read_some( 286   virtual capy::io_task<std::size_t> do_read_some(
287   capy::detail::mutable_buffer_array<capy::detail::max_iovec_> 287   capy::detail::mutable_buffer_array<capy::detail::max_iovec_>
288   buffers) = 0; 288   buffers) = 0;
289   289  
290   /** Perform the backend-specific encrypted write. 290   /** Perform the backend-specific encrypted write.
291   291  
292   Derived classes override this to perform TLS encryption 292   Derived classes override this to perform TLS encryption
293   and write operations. 293   and write operations.
294   294  
295   @param buffers Buffer sequence to write from. 295   @param buffers Buffer sequence to write from.
296   296  
297   @return An awaitable yielding `(error_code,std::size_t)`. 297   @return An awaitable yielding `(error_code,std::size_t)`.
298   */ 298   */
299   virtual capy::io_task<std::size_t> do_write_some( 299   virtual capy::io_task<std::size_t> do_write_some(
300   capy::detail::const_buffer_array<capy::detail::max_iovec_> buffers) = 0; 300   capy::detail::const_buffer_array<capy::detail::max_iovec_> buffers) = 0;
301   }; 301   };
302   302  
303   } // namespace boost::corosio 303   } // namespace boost::corosio
304   304  
305   #endif 305   #endif