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
183 : : 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 25 : : s_(s), endpoint_(ep) {}
191 :
192 25 : std::coroutine_handle<> dispatch(
193 : std::coroutine_handle<> h, capy::executor_ref ex) const
194 : {
195 25 : return s_.get().connect(h, ex, endpoint_, token_, &ec_);
196 : }
197 : };
198 :
199 : /// Represent the awaitable returned by @ref wait.
200 : struct wait_awaitable
201 : : detail::void_op_base<wait_awaitable>
202 : {
203 : local_stream_socket& s_;
204 : wait_type w_;
205 :
206 16 : wait_awaitable(local_stream_socket& s, wait_type w) noexcept
207 16 : : s_(s), w_(w) {}
208 :
209 16 : std::coroutine_handle<> dispatch(
210 : std::coroutine_handle<> h, capy::executor_ref ex) const
211 : {
212 16 : return s_.get().wait(h, ex, w_, token_, &ec_);
213 : }
214 : };
215 :
216 : public:
217 : /** Destructor.
218 :
219 : Closes the socket if open, cancelling any pending operations.
220 : */
221 : ~local_stream_socket() override;
222 :
223 : /** Construct a socket from an execution context.
224 :
225 : @param ctx The execution context that will own this socket.
226 : */
227 : explicit local_stream_socket(capy::execution_context& ctx);
228 :
229 : /** Construct a socket from an executor.
230 :
231 : The socket is associated with the executor's context.
232 :
233 : @param ex The executor whose context will own the socket.
234 : */
235 : template<class Ex>
236 : requires(!std::same_as<std::remove_cvref_t<Ex>, local_stream_socket>) &&
237 : capy::Executor<Ex>
238 : explicit local_stream_socket(Ex const& ex) : local_stream_socket(ex.context())
239 : {
240 : }
241 :
242 : /** Move constructor.
243 :
244 : Transfers ownership of the socket resources.
245 :
246 : @param other The socket to move from.
247 :
248 : @pre No awaitables returned by @p other's methods exist.
249 : @pre The execution context associated with @p other must
250 : outlive this socket.
251 : */
252 14 : local_stream_socket(local_stream_socket&& other) noexcept
253 14 : : io_object(std::move(other))
254 : {
255 14 : }
256 :
257 : /** Move assignment operator.
258 :
259 : Closes any existing socket and transfers ownership.
260 :
261 : @param other The socket to move from.
262 :
263 : @pre No awaitables returned by either `*this` or @p other's
264 : methods exist.
265 : @pre The execution context associated with @p other must
266 : outlive this socket.
267 :
268 : @return Reference to this socket.
269 : */
270 4 : local_stream_socket& operator=(local_stream_socket&& other) noexcept
271 : {
272 4 : if (this != &other)
273 : {
274 2 : close();
275 2 : io_object::operator=(std::move(other));
276 : }
277 4 : return *this;
278 : }
279 :
280 : local_stream_socket(local_stream_socket const&) = delete;
281 : local_stream_socket& operator=(local_stream_socket const&) = delete;
282 :
283 : /** Open the socket.
284 :
285 : Creates a Unix stream socket and associates it with
286 : the platform reactor.
287 :
288 : Failures such as descriptor exhaustion are normal runtime
289 : conditions and are reported through the returned error code.
290 : Opening an already-open socket is a no-op that reports
291 : success.
292 :
293 : @param proto The protocol. Defaults to local_stream{}.
294 :
295 : @return The error code, empty on success.
296 : */
297 : [[nodiscard]] std::error_code open(local_stream proto = {}) noexcept;
298 :
299 : /** Close the socket.
300 :
301 : Releases socket resources. Any pending operations complete
302 : with `errc::operation_canceled`.
303 : */
304 : void close() noexcept;
305 :
306 : /** Check if the socket is open.
307 :
308 : @return `true` if the socket is open and ready for operations.
309 : */
310 869 : bool is_open() const noexcept
311 : {
312 : #if BOOST_COROSIO_HAS_IOCP && !defined(BOOST_COROSIO_MRDOCS)
313 : return h_ && get().native_handle() != ~native_handle_type(0);
314 : #else
315 869 : return h_ && get().native_handle() >= 0;
316 : #endif
317 : }
318 :
319 : /** Initiate an asynchronous connect operation.
320 :
321 : If the socket is not already open, it is opened automatically.
322 :
323 : @param ep The local endpoint (path) to connect to.
324 :
325 : @return An awaitable that completes with io_result<>.
326 :
327 : If the socket needs to be opened and the open fails, the
328 : awaitable completes immediately with that error.
329 : */
330 25 : [[nodiscard]] auto connect(corosio::local_endpoint ep)
331 : {
332 25 : connect_awaitable aw(*this, ep);
333 25 : if (!is_open())
334 17 : aw.ec_ = open();
335 25 : return aw;
336 : }
337 :
338 : /** Wait for the socket to become ready in a given direction.
339 :
340 : Suspends until the socket is ready for the requested
341 : direction, or an error condition is reported. No bytes
342 : are transferred.
343 :
344 : @param w The wait direction (read, write, or error).
345 :
346 : @return An awaitable that completes with `io_result<>`.
347 :
348 : A closed socket completes with `errc::bad_file_descriptor`.
349 :
350 : @par Preconditions
351 : This socket must outlive the returned awaitable.
352 : */
353 16 : [[nodiscard]] auto wait(wait_type w)
354 : {
355 16 : return wait_awaitable(*this, w);
356 : }
357 :
358 : /** Cancel any pending asynchronous operations.
359 :
360 : All outstanding operations complete with `errc::operation_canceled`.
361 : Check `ec == cond::canceled` for portable comparison.
362 : */
363 : void cancel() noexcept;
364 :
365 : /** Get the native socket handle.
366 :
367 : Returns the underlying platform-specific socket descriptor.
368 : On POSIX systems this is an `int` file descriptor.
369 :
370 : @return The native socket handle, or an invalid sentinel
371 : if not open.
372 : */
373 : native_handle_type native_handle() const noexcept;
374 :
375 : /** Query the number of bytes available for reading.
376 :
377 : @return The number of bytes that can be read without blocking.
378 :
379 : @throws std::system_error `errc::bad_file_descriptor` if the
380 : socket is not open; otherwise thrown on ioctl failure.
381 : */
382 : std::size_t available() const;
383 :
384 : /** Release ownership of the native socket handle.
385 :
386 : Deregisters the socket from the backend and cancels pending
387 : operations without closing the descriptor. The caller takes
388 : ownership of the returned handle.
389 :
390 : @return The native handle.
391 :
392 : @throws std::system_error `errc::bad_file_descriptor` if the
393 : socket is not open.
394 :
395 : @post is_open() == false
396 : */
397 : native_handle_type release();
398 :
399 : /** Disable sends or receives on the socket.
400 :
401 : Unix stream connections are full-duplex: each direction
402 : (send and receive) operates independently. This function
403 : allows you to close one or both directions without
404 : destroying the socket.
405 :
406 : Failures such as a peer that already disconnected are
407 : normal runtime conditions and are reported through the
408 : returned error code. A closed socket reports
409 : `errc::bad_file_descriptor`.
410 :
411 : @param what Determines what operations will no longer
412 : be allowed.
413 :
414 : @return The error code, empty on success.
415 : */
416 : [[nodiscard]] std::error_code shutdown(shutdown_type what) noexcept;
417 :
418 : /** Set a socket option.
419 :
420 : Applies a type-safe socket option to the underlying socket.
421 : The option type encodes the protocol level and option name.
422 :
423 : @param opt The option to set.
424 :
425 : @throws std::system_error `errc::bad_file_descriptor` if the
426 : socket is not open; otherwise thrown on failure.
427 : */
428 : template<class Option>
429 14 : void set_option(Option const& opt)
430 : {
431 14 : if (!is_open())
432 2 : detail::throw_system_error(
433 4 : make_error_code(std::errc::bad_file_descriptor),
434 : "local_stream_socket::set_option");
435 12 : std::error_code ec = get().set_option(
436 : Option::level(), Option::name(), opt.data(), opt.size());
437 12 : if (ec)
438 2 : detail::throw_system_error(ec, "local_stream_socket::set_option");
439 10 : }
440 :
441 : /** Get a socket option.
442 :
443 : Retrieves the current value of a type-safe socket option.
444 :
445 : @return The current option value.
446 :
447 : @throws std::system_error `errc::bad_file_descriptor` if the
448 : socket is not open; otherwise thrown on failure.
449 : */
450 : template<class Option>
451 10 : Option get_option() const
452 : {
453 10 : if (!is_open())
454 2 : detail::throw_system_error(
455 4 : make_error_code(std::errc::bad_file_descriptor),
456 : "local_stream_socket::get_option");
457 8 : Option opt{};
458 8 : std::size_t sz = opt.size();
459 : std::error_code ec =
460 8 : get().get_option(Option::level(), Option::name(), opt.data(), &sz);
461 8 : if (ec)
462 2 : detail::throw_system_error(ec, "local_stream_socket::get_option");
463 6 : opt.resize(sz);
464 6 : return opt;
465 : }
466 :
467 : /** Assign an existing native socket to this object.
468 :
469 : Adopts a Unix domain stream socket created outside the
470 : library — from `socketpair()`, received over `SCM_RIGHTS`,
471 : or made natively — and registers it with the backend. The
472 : socket must be a stream socket in the `AF_UNIX` family.
473 : Adoption never alters the descriptor's flags or options: on
474 : POSIX the fd must already be non-blocking, and on Windows
475 : the socket must be overlapped-capable.
476 :
477 : If this object is already open, pending operations complete
478 : with `errc::operation_canceled` and the held socket is
479 : closed before the new one is adopted.
480 :
481 : @par Exception Safety
482 : Strong guarantee on validation failure: the object is
483 : unchanged. If backend registration fails, the object either
484 : retains its previous socket or is left closed, depending on
485 : the backend. In all failure cases the caller retains
486 : ownership of `fd`.
487 :
488 : @param fd The native socket to adopt. On success the object
489 : owns it and will close it.
490 :
491 : @return The error code, empty on success. Validation and
492 : registration failures are normal runtime conditions when
493 : adopting foreign descriptors.
494 : */
495 : [[nodiscard]] std::error_code assign(native_handle_type fd) noexcept;
496 :
497 : /** Get the local endpoint of the socket.
498 :
499 : Returns the local address (path) to which the socket is bound.
500 : The endpoint is cached when the connection is established.
501 :
502 : @return The local endpoint, or a default endpoint if the socket
503 : is not connected.
504 : */
505 : corosio::local_endpoint local_endpoint() const noexcept;
506 :
507 : /** Get the remote endpoint of the socket.
508 :
509 : Returns the remote address (path) to which the socket is connected.
510 : The endpoint is cached when the connection is established.
511 :
512 : @return The remote endpoint, or a default endpoint if the socket
513 : is not connected.
514 : */
515 : corosio::local_endpoint remote_endpoint() const noexcept;
516 :
517 : protected:
518 44 : local_stream_socket() noexcept = default;
519 :
520 : explicit local_stream_socket(handle h) noexcept : io_object(std::move(h)) {}
521 :
522 : private:
523 : friend class local_stream_acceptor;
524 :
525 : [[nodiscard]] std::error_code
526 : open_for_family(int family, int type, int protocol) noexcept;
527 :
528 951 : inline implementation& get() const noexcept
529 : {
530 951 : return *static_cast<implementation*>(h_.get());
531 : }
532 : };
533 :
534 : } // namespace boost::corosio
535 :
536 : #endif // BOOST_COROSIO_LOCAL_STREAM_SOCKET_HPP
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