TLA Line data Source code
1 : //
2 : // Copyright (c) 2026 Michael Vandeberg
3 : //
4 : // Distributed under the Boost Software License, Version 1.0. (See accompanying
5 : // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6 : //
7 : // Official repository: https://github.com/cppalliance/corosio
8 : //
9 :
10 : #ifndef BOOST_COROSIO_LOCAL_STREAM_SOCKET_HPP
11 : #define BOOST_COROSIO_LOCAL_STREAM_SOCKET_HPP
12 :
13 : #include <boost/corosio/detail/config.hpp>
14 : #include <boost/corosio/detail/platform.hpp>
15 : #include <boost/corosio/detail/except.hpp>
16 : #include <boost/corosio/detail/native_handle.hpp>
17 : #include <boost/corosio/detail/op_base.hpp>
18 : #include <boost/corosio/io/io_stream.hpp>
19 : #include <boost/capy/io_result.hpp>
20 : #include <boost/corosio/detail/buffer_param.hpp>
21 : #include <boost/corosio/local_endpoint.hpp>
22 : #include <boost/corosio/local_stream.hpp>
23 : #include <boost/corosio/shutdown_type.hpp>
24 : #include <boost/corosio/wait_type.hpp>
25 : #include <boost/capy/ex/executor_ref.hpp>
26 : #include <boost/capy/ex/execution_context.hpp>
27 : #include <boost/capy/ex/io_env.hpp>
28 : #include <boost/capy/concept/executor.hpp>
29 :
30 : #include <system_error>
31 :
32 : #include <concepts>
33 : #include <coroutine>
34 : #include <cstddef>
35 : #include <stop_token>
36 : #include <type_traits>
37 :
38 : namespace boost::corosio {
39 :
40 : /** An asynchronous Unix stream socket for coroutine I/O.
41 :
42 : This class provides asynchronous Unix domain stream socket
43 : operations that return awaitable types. Each operation
44 : participates in the affine awaitable protocol, ensuring
45 : coroutines resume on the correct executor.
46 :
47 : The socket must be opened before performing I/O operations.
48 : Operations support cancellation through `std::stop_token` via
49 : the affine protocol, or explicitly through the `cancel()`
50 : member function.
51 :
52 : @par Thread Safety
53 : Distinct objects: Safe.@n
54 : Shared objects: Unsafe. A socket must not have concurrent
55 : operations of the same type (e.g., two simultaneous reads).
56 : One read and one write may be in flight simultaneously.
57 :
58 : @par Semantics
59 : Wraps the platform Unix domain socket stack. Operations
60 : dispatch to OS socket APIs via the io_context backend
61 : (epoll, kqueue, select, or IOCP). Satisfies @ref capy::Stream.
62 :
63 : @par Example
64 : @par !example connect_and_read
65 : */
66 : class BOOST_COROSIO_DECL local_stream_socket : public io_stream
67 : {
68 : public:
69 : /// The endpoint type used by this socket.
70 : using endpoint_type = corosio::local_endpoint;
71 :
72 : using shutdown_type = corosio::shutdown_type;
73 : using enum corosio::shutdown_type;
74 :
75 : /** Define backend hooks for local stream socket operations.
76 :
77 : Platform backends (epoll, kqueue, select) derive from this
78 : to implement socket I/O, connection, and option management.
79 : */
80 : struct implementation : io_stream::implementation
81 : {
82 : /** Initiate an asynchronous connect to the given endpoint.
83 :
84 : @param h Coroutine handle to resume on completion.
85 : @param ex Executor for dispatching the completion.
86 : @param ep The local endpoint (path) to connect to.
87 : @param token Stop token for cancellation.
88 : @param ec Output error code.
89 :
90 : @return Coroutine handle to resume immediately.
91 : */
92 : virtual std::coroutine_handle<> connect(
93 : std::coroutine_handle<> h,
94 : capy::executor_ref ex,
95 : corosio::local_endpoint ep,
96 : std::stop_token token,
97 : std::error_code* ec) = 0;
98 :
99 : /** Initiate an asynchronous wait for socket readiness.
100 :
101 : Completes when the socket becomes ready for the
102 : specified direction, or an error condition is
103 : reported. No bytes are transferred.
104 :
105 : @param h Coroutine handle to resume on completion.
106 : @param ex Executor for dispatching the completion.
107 : @param w The direction to wait on.
108 : @param token Stop token for cancellation.
109 : @param ec Output error code.
110 :
111 : @return Coroutine handle to resume immediately.
112 : */
113 : virtual std::coroutine_handle<> wait(
114 : std::coroutine_handle<> h,
115 : capy::executor_ref ex,
116 : wait_type w,
117 : std::stop_token token,
118 : std::error_code* ec) = 0;
119 :
120 : /** Shut down the socket for the given direction(s).
121 :
122 : @param what The shutdown direction.
123 :
124 : @return Error code on failure, empty on success.
125 : */
126 : virtual std::error_code shutdown(shutdown_type what) noexcept = 0;
127 :
128 : /// Return the platform socket descriptor.
129 : virtual native_handle_type native_handle() const noexcept = 0;
130 :
131 : /** Release ownership of the native socket handle.
132 :
133 : Deregisters the socket from the reactor without closing
134 : the descriptor. The caller takes ownership.
135 :
136 : @return The native handle.
137 : */
138 : virtual native_handle_type release_socket() noexcept = 0;
139 :
140 : /** Request cancellation of pending asynchronous operations.
141 :
142 : All outstanding operations complete with operation_canceled error.
143 : Check `ec == cond::canceled` for portable comparison.
144 : */
145 : virtual void cancel() noexcept = 0;
146 :
147 : /** Set a socket option.
148 :
149 : @param level The protocol level (e.g. `SOL_SOCKET`).
150 : @param optname The option name (e.g. `SO_KEEPALIVE`).
151 : @param data Pointer to the option value.
152 : @param size Size of the option value in bytes.
153 : @return Error code on failure, empty on success.
154 : */
155 : virtual std::error_code set_option(
156 : int level,
157 : int optname,
158 : void const* data,
159 : std::size_t size) noexcept = 0;
160 :
161 : /** Get a socket option.
162 :
163 : @param level The protocol level (e.g. `SOL_SOCKET`).
164 : @param optname The option name (e.g. `SO_KEEPALIVE`).
165 : @param data Pointer to receive the option value.
166 : @param size On entry, the size of the buffer. On exit,
167 : the size of the option value.
168 : @return Error code on failure, empty on success.
169 : */
170 : virtual std::error_code
171 : get_option(int level, int optname, void* data, std::size_t* size)
172 : const noexcept = 0;
173 :
174 : /// Return the cached local endpoint.
175 : virtual corosio::local_endpoint local_endpoint() const noexcept = 0;
176 :
177 : /// Return the cached remote endpoint.
178 : virtual corosio::local_endpoint remote_endpoint() const noexcept = 0;
179 : };
180 :
181 : /// Represent the awaitable returned by @ref connect.
182 : struct connect_awaitable : detail::void_op_base<connect_awaitable>
183 : {
184 : local_stream_socket& s_;
185 : corosio::local_endpoint endpoint_;
186 :
187 HIT 25 : connect_awaitable(
188 : local_stream_socket& s, corosio::local_endpoint ep) noexcept
189 50 : : s_(s)
190 25 : , endpoint_(ep)
191 : {
192 25 : }
193 :
194 : std::coroutine_handle<>
195 25 : dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
196 : {
197 25 : return s_.get().connect(h, ex, endpoint_, token_, &ec_);
198 : }
199 : };
200 :
201 : /// Represent the awaitable returned by @ref wait.
202 : struct wait_awaitable : detail::void_op_base<wait_awaitable>
203 : {
204 : local_stream_socket& s_;
205 : wait_type w_;
206 :
207 16 : wait_awaitable(local_stream_socket& s, wait_type w) noexcept
208 32 : : s_(s)
209 16 : , w_(w)
210 : {
211 16 : }
212 :
213 : std::coroutine_handle<>
214 16 : dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
215 : {
216 16 : return s_.get().wait(h, ex, w_, token_, &ec_);
217 : }
218 : };
219 :
220 : public:
221 : /** Destructor.
222 :
223 : Closes the socket if open, cancelling any pending operations.
224 : */
225 : ~local_stream_socket() override;
226 :
227 : /** Construct a socket from an execution context.
228 :
229 : @param ctx The execution context that will own this socket.
230 : */
231 : explicit local_stream_socket(capy::execution_context& ctx);
232 :
233 : /** Construct a socket from an executor.
234 :
235 : The socket is associated with the executor's context.
236 :
237 : @param ex The executor whose context will own the socket.
238 : */
239 : template<class Ex>
240 : requires(!std::same_as<std::remove_cvref_t<Ex>, local_stream_socket>) &&
241 : capy::Executor<Ex>
242 : explicit local_stream_socket(Ex const& ex)
243 : : local_stream_socket(ex.context())
244 : {
245 : }
246 :
247 : /** Move constructor.
248 :
249 : Transfers ownership of the socket resources.
250 :
251 : @param other The socket to move from.
252 :
253 : @pre No awaitables returned by @p other's methods exist.
254 : @pre The execution context associated with @p other must
255 : outlive this socket.
256 : */
257 14 : local_stream_socket(local_stream_socket&& other) noexcept
258 14 : : io_object(std::move(other))
259 : {
260 14 : }
261 :
262 : /** Move assignment operator.
263 :
264 : Closes any existing socket and transfers ownership.
265 :
266 : @param other The socket to move from.
267 :
268 : @pre No awaitables returned by either `*this` or @p other's
269 : methods exist.
270 : @pre The execution context associated with @p other must
271 : outlive this socket.
272 :
273 : @return Reference to this socket.
274 : */
275 4 : local_stream_socket& operator=(local_stream_socket&& other) noexcept
276 : {
277 4 : if (this != &other)
278 : {
279 2 : close();
280 2 : io_object::operator=(std::move(other));
281 : }
282 4 : return *this;
283 : }
284 :
285 : local_stream_socket(local_stream_socket const&) = delete;
286 : local_stream_socket& operator=(local_stream_socket const&) = delete;
287 :
288 : /** Open the socket.
289 :
290 : Creates a Unix stream socket and associates it with
291 : the platform reactor.
292 :
293 : Failures such as descriptor exhaustion are normal runtime
294 : conditions and are reported through the returned error code.
295 : Opening an already-open socket is a no-op that reports
296 : success.
297 :
298 : @param proto The protocol. Defaults to local_stream{}.
299 :
300 : @return The error code, empty on success.
301 : */
302 : [[nodiscard]] std::error_code open(local_stream proto = {}) noexcept;
303 :
304 : /** Close the socket.
305 :
306 : Releases socket resources. Any pending operations complete
307 : with `errc::operation_canceled`.
308 : */
309 : void close() noexcept;
310 :
311 : /** Check if the socket is open.
312 :
313 : @return `true` if the socket is open and ready for operations.
314 : */
315 869 : bool is_open() const noexcept
316 : {
317 : #if BOOST_COROSIO_HAS_IOCP && !defined(BOOST_COROSIO_MRDOCS)
318 : return h_ && get().native_handle() != ~native_handle_type(0);
319 : #else
320 869 : return h_ && get().native_handle() >= 0;
321 : #endif
322 : }
323 :
324 : /** Initiate an asynchronous connect operation.
325 :
326 : If the socket is not already open, it is opened automatically.
327 :
328 : @param ep The local endpoint (path) to connect to.
329 :
330 : @return An awaitable that completes with io_result<>.
331 :
332 : If the socket needs to be opened and the open fails, the
333 : awaitable completes immediately with that error.
334 : */
335 25 : [[nodiscard]] auto connect(corosio::local_endpoint ep)
336 : {
337 25 : connect_awaitable aw(*this, ep);
338 25 : if (!is_open())
339 17 : aw.ec_ = open();
340 25 : return aw;
341 : }
342 :
343 : /** Wait for the socket to become ready in a given direction.
344 :
345 : Suspends until the socket is ready for the requested
346 : direction, or an error condition is reported. No bytes
347 : are transferred.
348 :
349 : @param w The wait direction (read, write, or error).
350 :
351 : @return An awaitable that completes with `io_result<>`.
352 :
353 : A closed socket completes with `errc::bad_file_descriptor`.
354 :
355 : @par Preconditions
356 : This socket must outlive the returned awaitable.
357 : */
358 16 : [[nodiscard]] auto wait(wait_type w)
359 : {
360 16 : return wait_awaitable(*this, w);
361 : }
362 :
363 : /** Cancel any pending asynchronous operations.
364 :
365 : All outstanding operations complete with `errc::operation_canceled`.
366 : Check `ec == cond::canceled` for portable comparison.
367 : */
368 : void cancel() noexcept;
369 :
370 : /** Get the native socket handle.
371 :
372 : Returns the underlying platform-specific socket descriptor.
373 : On POSIX systems this is an `int` file descriptor.
374 :
375 : @return The native socket handle, or an invalid sentinel
376 : if not open.
377 : */
378 : native_handle_type native_handle() const noexcept;
379 :
380 : /** Query the number of bytes available for reading.
381 :
382 : @return The number of bytes that can be read without blocking.
383 :
384 : @throws std::system_error `errc::bad_file_descriptor` if the
385 : socket is not open; otherwise thrown on ioctl failure.
386 : */
387 : std::size_t available() const;
388 :
389 : /** Release ownership of the native socket handle.
390 :
391 : Deregisters the socket from the backend and cancels pending
392 : operations without closing the descriptor. The caller takes
393 : ownership of the returned handle.
394 :
395 : @return The native handle.
396 :
397 : @throws std::system_error `errc::bad_file_descriptor` if the
398 : socket is not open.
399 :
400 : @post is_open() == false
401 : */
402 : native_handle_type release();
403 :
404 : /** Disable sends or receives on the socket.
405 :
406 : Unix stream connections are full-duplex: each direction
407 : (send and receive) operates independently. This function
408 : allows you to close one or both directions without
409 : destroying the socket.
410 :
411 : Failures such as a peer that already disconnected are
412 : normal runtime conditions and are reported through the
413 : returned error code. A closed socket reports
414 : `errc::bad_file_descriptor`.
415 :
416 : @param what Determines what operations will no longer
417 : be allowed.
418 :
419 : @return The error code, empty on success.
420 : */
421 : [[nodiscard]] std::error_code shutdown(shutdown_type what) noexcept;
422 :
423 : /** Set a socket option.
424 :
425 : Applies a type-safe socket option to the underlying socket.
426 : The option type encodes the protocol level and option name.
427 :
428 : @param opt The option to set.
429 :
430 : @throws std::system_error `errc::bad_file_descriptor` if the
431 : socket is not open; otherwise thrown on failure.
432 : */
433 : template<class Option>
434 14 : void set_option(Option const& opt)
435 : {
436 14 : if (!is_open())
437 2 : detail::throw_system_error(
438 4 : make_error_code(std::errc::bad_file_descriptor),
439 : "local_stream_socket::set_option");
440 12 : std::error_code ec = get().set_option(
441 : Option::level(), Option::name(), opt.data(), opt.size());
442 12 : if (ec)
443 2 : detail::throw_system_error(ec, "local_stream_socket::set_option");
444 10 : }
445 :
446 : /** Get a socket option.
447 :
448 : Retrieves the current value of a type-safe socket option.
449 :
450 : @return The current option value.
451 :
452 : @throws std::system_error `errc::bad_file_descriptor` if the
453 : socket is not open; otherwise thrown on failure.
454 : */
455 : template<class Option>
456 10 : Option get_option() const
457 : {
458 10 : if (!is_open())
459 2 : detail::throw_system_error(
460 4 : make_error_code(std::errc::bad_file_descriptor),
461 : "local_stream_socket::get_option");
462 8 : Option opt{};
463 8 : std::size_t sz = opt.size();
464 : std::error_code ec =
465 8 : get().get_option(Option::level(), Option::name(), opt.data(), &sz);
466 8 : if (ec)
467 2 : detail::throw_system_error(ec, "local_stream_socket::get_option");
468 6 : opt.resize(sz);
469 6 : return opt;
470 : }
471 :
472 : /** Assign an existing native socket to this object.
473 :
474 : Adopts a Unix domain stream socket created outside the
475 : library — from `socketpair()`, received over `SCM_RIGHTS`,
476 : or made natively — and registers it with the backend. The
477 : socket must be a stream socket in the `AF_UNIX` family.
478 : Adoption never alters the descriptor's flags or options: on
479 : POSIX the fd must already be non-blocking, and on Windows
480 : the socket must be overlapped-capable.
481 :
482 : If this object is already open, pending operations complete
483 : with `errc::operation_canceled` and the held socket is
484 : closed before the new one is adopted.
485 :
486 : @par Exception Safety
487 : Strong guarantee on validation failure: the object is
488 : unchanged. If backend registration fails, the object either
489 : retains its previous socket or is left closed, depending on
490 : the backend. In all failure cases the caller retains
491 : ownership of `fd`.
492 :
493 : @param fd The native socket to adopt. On success the object
494 : owns it and will close it.
495 :
496 : @return The error code, empty on success. Validation and
497 : registration failures are normal runtime conditions when
498 : adopting foreign descriptors.
499 : */
500 : [[nodiscard]] std::error_code assign(native_handle_type fd) noexcept;
501 :
502 : /** Get the local endpoint of the socket.
503 :
504 : Returns the local address (path) to which the socket is bound.
505 : The endpoint is cached when the connection is established.
506 :
507 : @return The local endpoint, or a default endpoint if the socket
508 : is not connected.
509 : */
510 : corosio::local_endpoint local_endpoint() const noexcept;
511 :
512 : /** Get the remote endpoint of the socket.
513 :
514 : Returns the remote address (path) to which the socket is connected.
515 : The endpoint is cached when the connection is established.
516 :
517 : @return The remote endpoint, or a default endpoint if the socket
518 : is not connected.
519 : */
520 : corosio::local_endpoint remote_endpoint() const noexcept;
521 :
522 : protected:
523 44 : local_stream_socket() noexcept = default;
524 :
525 : explicit local_stream_socket(handle h) noexcept : io_object(std::move(h)) {}
526 :
527 : private:
528 : friend class local_stream_acceptor;
529 :
530 : [[nodiscard]] std::error_code
531 : open_for_family(int family, int type, int protocol) noexcept;
532 :
533 951 : inline implementation& get() const noexcept
534 : {
535 951 : return *static_cast<implementation*>(h_.get());
536 : }
537 : };
538 :
539 : } // namespace boost::corosio
540 :
541 : #endif // BOOST_COROSIO_LOCAL_STREAM_SOCKET_HPP
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