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 : Operations still in flight complete with `operation_canceled`; an
143 : operation whose result is already decided reports that result.
144 : Check `ec == cond::canceled` for portable comparison.
145 : */
146 : virtual void cancel() noexcept = 0;
147 :
148 : /** Set a socket option.
149 :
150 : @param level The protocol level (e.g. `SOL_SOCKET`).
151 : @param optname The option name (e.g. `SO_KEEPALIVE`).
152 : @param data Pointer to the option value.
153 : @param size Size of the option value in bytes.
154 : @return Error code on failure, empty on success.
155 : */
156 : virtual std::error_code set_option(
157 : int level,
158 : int optname,
159 : void const* data,
160 : std::size_t size) noexcept = 0;
161 :
162 : /** Get a socket option.
163 :
164 : @param level The protocol level (e.g. `SOL_SOCKET`).
165 : @param optname The option name (e.g. `SO_KEEPALIVE`).
166 : @param data Pointer to receive the option value.
167 : @param size On entry, the size of the buffer. On exit,
168 : the size of the option value.
169 : @return Error code on failure, empty on success.
170 : */
171 : virtual std::error_code
172 : get_option(int level, int optname, void* data, std::size_t* size)
173 : const noexcept = 0;
174 :
175 : /// Return the cached local endpoint.
176 : virtual corosio::local_endpoint local_endpoint() const noexcept = 0;
177 :
178 : /// Return the cached remote endpoint.
179 : virtual corosio::local_endpoint remote_endpoint() const noexcept = 0;
180 : };
181 :
182 : /// Represent the awaitable returned by @ref connect.
183 : struct connect_awaitable : detail::void_op_base<connect_awaitable>
184 : {
185 : local_stream_socket& s_;
186 : corosio::local_endpoint endpoint_;
187 :
188 HIT 25 : connect_awaitable(
189 : local_stream_socket& s, corosio::local_endpoint ep) noexcept
190 50 : : s_(s)
191 25 : , endpoint_(ep)
192 : {
193 25 : }
194 :
195 : std::coroutine_handle<>
196 23 : dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
197 : {
198 23 : return s_.get().connect(h, ex, endpoint_, token_, &ec_);
199 : }
200 : };
201 :
202 : /// Represent the awaitable returned by @ref wait.
203 : struct wait_awaitable : detail::void_op_base<wait_awaitable>
204 : {
205 : local_stream_socket& s_;
206 : wait_type w_;
207 :
208 16 : wait_awaitable(local_stream_socket& s, wait_type w) noexcept
209 32 : : s_(s)
210 16 : , w_(w)
211 : {
212 16 : }
213 :
214 : std::coroutine_handle<>
215 14 : dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
216 : {
217 14 : return s_.get().wait(h, ex, w_, token_, &ec_);
218 : }
219 : };
220 :
221 : public:
222 : /** Destructor.
223 :
224 : Closes the socket if open, cancelling any pending operations.
225 : */
226 : ~local_stream_socket() override;
227 :
228 : /** Construct a socket from an execution context.
229 :
230 : @param ctx The execution context that will own this socket.
231 : */
232 : explicit local_stream_socket(capy::execution_context& ctx);
233 :
234 : /** Construct a socket from an executor.
235 :
236 : The socket is associated with the executor's context.
237 :
238 : @param ex The executor whose context will own the socket.
239 : */
240 : template<class Ex>
241 : requires(!std::same_as<std::remove_cvref_t<Ex>, local_stream_socket>) &&
242 : capy::Executor<Ex>
243 : explicit local_stream_socket(Ex const& ex)
244 : : local_stream_socket(ex.context())
245 : {
246 : }
247 :
248 : /** Move constructor.
249 :
250 : Transfers ownership of the socket resources.
251 :
252 : @param other The socket to move from.
253 :
254 : @pre No awaitables returned by @p other's methods exist.
255 : @pre The execution context associated with @p other must
256 : outlive this socket.
257 : */
258 14 : local_stream_socket(local_stream_socket&& other) noexcept
259 14 : : io_object(std::move(other))
260 : {
261 14 : }
262 :
263 : /** Move assignment operator.
264 :
265 : Closes any existing socket and transfers ownership.
266 :
267 : @param other The socket to move from.
268 :
269 : @pre No awaitables returned by either `*this` or @p other's
270 : methods exist.
271 : @pre The execution context associated with @p other must
272 : outlive this socket.
273 :
274 : @return Reference to this socket.
275 : */
276 4 : local_stream_socket& operator=(local_stream_socket&& other) noexcept
277 : {
278 4 : if (this != &other)
279 : {
280 2 : close();
281 2 : io_object::operator=(std::move(other));
282 : }
283 4 : return *this;
284 : }
285 :
286 : local_stream_socket(local_stream_socket const&) = delete;
287 : local_stream_socket& operator=(local_stream_socket const&) = delete;
288 :
289 : /** Open the socket.
290 :
291 : Creates a Unix stream socket and associates it with
292 : the platform reactor.
293 :
294 : Failures such as descriptor exhaustion are normal runtime
295 : conditions and are reported through the returned error code.
296 : Opening an already-open socket is a no-op that reports
297 : success.
298 :
299 : @param proto The protocol. Defaults to local_stream{}.
300 :
301 : @return The error code, empty on success.
302 : */
303 : [[nodiscard]] std::error_code open(local_stream proto = {}) noexcept;
304 :
305 : /** Close the socket.
306 :
307 : Releases socket resources. Any pending operations complete
308 : with `errc::operation_canceled`.
309 : */
310 : void close() noexcept;
311 :
312 : /** Check if the socket is open.
313 :
314 : @return `true` if the socket is open and ready for operations.
315 : */
316 869 : bool is_open() const noexcept
317 : {
318 : #if BOOST_COROSIO_HAS_IOCP && !defined(BOOST_COROSIO_MRDOCS)
319 : return h_ && get().native_handle() != ~native_handle_type(0);
320 : #else
321 869 : return h_ && get().native_handle() >= 0;
322 : #endif
323 : }
324 :
325 : /** Initiate an asynchronous connect operation.
326 :
327 : If the socket is not already open, it is opened automatically.
328 :
329 : @param ep The local endpoint (path) to connect to.
330 :
331 : @return An awaitable that completes with io_result<>.
332 :
333 : If the socket needs to be opened and the open fails, the
334 : awaitable completes immediately with that error.
335 : */
336 25 : [[nodiscard]] auto connect(corosio::local_endpoint ep)
337 : {
338 25 : connect_awaitable aw(*this, ep);
339 25 : if (!is_open())
340 17 : aw.ec_ = open();
341 25 : return aw;
342 : }
343 :
344 : /** Wait for the socket to become ready in a given direction.
345 :
346 : Suspends until the socket is ready for the requested
347 : direction, or an error condition is reported. No bytes
348 : are transferred.
349 :
350 : @param w The wait direction (read, write, or error).
351 :
352 : @return An awaitable that completes with `io_result<>`.
353 :
354 : A closed socket completes with `errc::bad_file_descriptor`.
355 :
356 : @par Preconditions
357 : This socket must outlive the returned awaitable.
358 : */
359 16 : [[nodiscard]] auto wait(wait_type w)
360 : {
361 16 : return wait_awaitable(*this, w);
362 : }
363 :
364 : /** Cancel any pending asynchronous operations.
365 :
366 : Operations still in flight complete with `errc::operation_canceled`;
367 : an operation whose result is already decided reports that result.
368 : Check `ec == cond::canceled` for portable comparison.
369 : */
370 : void cancel() noexcept;
371 :
372 : /** Get the native socket handle.
373 :
374 : Returns the underlying platform-specific socket descriptor.
375 : On POSIX systems this is an `int` file descriptor.
376 :
377 : @return The native socket handle, or an invalid sentinel
378 : if not open.
379 : */
380 : native_handle_type native_handle() const noexcept;
381 :
382 : /** Query the number of bytes available for reading.
383 :
384 : @return The number of bytes that can be read without blocking.
385 :
386 : @throws std::system_error `errc::bad_file_descriptor` if the
387 : socket is not open; otherwise thrown on ioctl failure.
388 : */
389 : std::size_t available() const;
390 :
391 : /** Release ownership of the native socket handle.
392 :
393 : Deregisters the socket from the backend and cancels pending
394 : operations without closing the descriptor. The caller takes
395 : ownership of the returned handle.
396 :
397 : @return The native handle.
398 :
399 : @throws std::system_error `errc::bad_file_descriptor` if the
400 : socket is not open.
401 :
402 : @post is_open() == false
403 : */
404 : native_handle_type release();
405 :
406 : /** Disable sends or receives on the socket.
407 :
408 : Unix stream connections are full-duplex: each direction
409 : (send and receive) operates independently. This function
410 : allows you to close one or both directions without
411 : destroying the socket.
412 :
413 : Failures such as a peer that already disconnected are
414 : normal runtime conditions and are reported through the
415 : returned error code. A closed socket reports
416 : `errc::bad_file_descriptor`.
417 :
418 : @param what Determines what operations will no longer
419 : be allowed.
420 :
421 : @return The error code, empty on success.
422 : */
423 : [[nodiscard]] std::error_code shutdown(shutdown_type what) noexcept;
424 :
425 : /** Set a socket option.
426 :
427 : Applies a type-safe socket option to the underlying socket.
428 : The option type encodes the protocol level and option name.
429 :
430 : @param opt The option to set.
431 :
432 : @throws std::system_error `errc::bad_file_descriptor` if the
433 : socket is not open; otherwise thrown on failure.
434 : */
435 : template<class Option>
436 14 : void set_option(Option const& opt)
437 : {
438 14 : if (!is_open())
439 2 : detail::throw_system_error(
440 4 : make_error_code(std::errc::bad_file_descriptor),
441 : "local_stream_socket::set_option");
442 12 : std::error_code ec = get().set_option(
443 : Option::level(), Option::name(), opt.data(), opt.size());
444 12 : if (ec)
445 2 : detail::throw_system_error(ec, "local_stream_socket::set_option");
446 10 : }
447 :
448 : /** Get a socket option.
449 :
450 : Retrieves the current value of a type-safe socket option.
451 :
452 : @return The current option value.
453 :
454 : @throws std::system_error `errc::bad_file_descriptor` if the
455 : socket is not open; otherwise thrown on failure.
456 : */
457 : template<class Option>
458 10 : Option get_option() const
459 : {
460 10 : if (!is_open())
461 2 : detail::throw_system_error(
462 4 : make_error_code(std::errc::bad_file_descriptor),
463 : "local_stream_socket::get_option");
464 8 : Option opt{};
465 8 : std::size_t sz = opt.size();
466 : std::error_code ec =
467 8 : get().get_option(Option::level(), Option::name(), opt.data(), &sz);
468 8 : if (ec)
469 2 : detail::throw_system_error(ec, "local_stream_socket::get_option");
470 6 : opt.resize(sz);
471 6 : return opt;
472 : }
473 :
474 : /** Assign an existing native socket to this object.
475 :
476 : Adopts a Unix domain stream socket created outside the
477 : library — from `socketpair()`, received over `SCM_RIGHTS`,
478 : or made natively — and registers it with the backend. The
479 : socket must be a stream socket in the `AF_UNIX` family.
480 : Adoption never alters the descriptor's flags or options: on
481 : POSIX the fd must already be non-blocking, and on Windows
482 : the socket must be overlapped-capable.
483 :
484 : If this object is already open, pending operations complete
485 : with `errc::operation_canceled` and the held socket is
486 : closed before the new one is adopted.
487 :
488 : @par Exception Safety
489 : Strong guarantee on validation failure: the object is
490 : unchanged. If backend registration fails, the object either
491 : retains its previous socket or is left closed, depending on
492 : the backend. In all failure cases the caller retains
493 : ownership of `fd`.
494 :
495 : @param fd The native socket to adopt. On success the object
496 : owns it and will close it.
497 :
498 : @return The error code, empty on success. Validation and
499 : registration failures are normal runtime conditions when
500 : adopting foreign descriptors.
501 : */
502 : [[nodiscard]] std::error_code assign(native_handle_type fd) noexcept;
503 :
504 : /** Get the local endpoint of the socket.
505 :
506 : Returns the local address (path) to which the socket is bound.
507 : The endpoint is cached when the connection is established.
508 :
509 : @return The local endpoint, or a default endpoint if the socket
510 : is not connected.
511 : */
512 : corosio::local_endpoint local_endpoint() const noexcept;
513 :
514 : /** Get the remote endpoint of the socket.
515 :
516 : Returns the remote address (path) to which the socket is connected.
517 : The endpoint is cached when the connection is established.
518 :
519 : @return The remote endpoint, or a default endpoint if the socket
520 : is not connected.
521 : */
522 : corosio::local_endpoint remote_endpoint() const noexcept;
523 :
524 : protected:
525 44 : local_stream_socket() noexcept = default;
526 :
527 : explicit local_stream_socket(handle h) noexcept : io_object(std::move(h)) {}
528 :
529 : private:
530 : friend class local_stream_acceptor;
531 :
532 : [[nodiscard]] std::error_code
533 : open_for_family(int family, int type, int protocol) noexcept;
534 :
535 947 : inline implementation& get() const noexcept
536 : {
537 947 : return *static_cast<implementation*>(h_.get());
538 : }
539 : };
540 :
541 : } // namespace boost::corosio
542 :
543 : #endif // BOOST_COROSIO_LOCAL_STREAM_SOCKET_HPP
|
