TLA Line data Source code
1 : //
2 : // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3 : // Copyright (c) 2026 Steve Gerbino
4 : // Copyright (c) 2026 Michael Vandeberg
5 : //
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)
8 : //
9 : // Official repository: https://github.com/cppalliance/corosio
10 : //
11 :
12 : #ifndef BOOST_COROSIO_TCP_SOCKET_HPP
13 : #define BOOST_COROSIO_TCP_SOCKET_HPP
14 :
15 : #include <boost/corosio/detail/config.hpp>
16 : #include <boost/corosio/detail/platform.hpp>
17 : #include <boost/corosio/detail/except.hpp>
18 : #include <boost/corosio/detail/native_handle.hpp>
19 : #include <boost/corosio/detail/op_base.hpp>
20 : #include <boost/corosio/io/io_stream.hpp>
21 : #include <boost/capy/io_result.hpp>
22 : #include <boost/corosio/detail/buffer_param.hpp>
23 : #include <boost/corosio/endpoint.hpp>
24 : #include <boost/corosio/shutdown_type.hpp>
25 : #include <boost/corosio/tcp.hpp>
26 : #include <boost/corosio/wait_type.hpp>
27 : #include <boost/capy/ex/executor_ref.hpp>
28 : #include <boost/capy/ex/execution_context.hpp>
29 : #include <boost/capy/ex/io_env.hpp>
30 : #include <boost/capy/concept/executor.hpp>
31 :
32 : #include <system_error>
33 :
34 : #include <concepts>
35 : #include <coroutine>
36 : #include <cstddef>
37 : #include <stop_token>
38 : #include <type_traits>
39 :
40 : namespace boost::corosio {
41 :
42 : /** An asynchronous TCP socket for coroutine I/O.
43 :
44 : This class provides asynchronous TCP socket operations that return
45 : awaitable types. Each operation participates in the affine awaitable
46 : protocol, ensuring coroutines resume on the correct executor.
47 :
48 : The socket must be opened before performing I/O operations. Operations
49 : support cancellation through `std::stop_token` via the affine protocol,
50 : or explicitly through the `cancel()` member function.
51 :
52 : @par Thread Safety
53 : Distinct objects: Safe.@n
54 : Shared objects: Unsafe. A socket must not have concurrent operations
55 : of the same type (e.g., two simultaneous reads). One read and one
56 : write may be in flight simultaneously.
57 :
58 : @par Semantics
59 : Wraps the platform TCP/IP stack. Operations dispatch to
60 : OS socket APIs via the io_context reactor (epoll, IOCP,
61 : kqueue). Satisfies @ref capy::Stream.
62 :
63 : @par Example
64 : @par !example connect_and_read
65 : */
66 : class BOOST_COROSIO_DECL tcp_socket : public io_stream
67 : {
68 : public:
69 : /// The endpoint type used by this socket.
70 : using endpoint_type = corosio::endpoint;
71 :
72 : using shutdown_type = corosio::shutdown_type;
73 : using enum corosio::shutdown_type;
74 :
75 : /** Define backend hooks for TCP socket operations.
76 :
77 : Platform backends (epoll, IOCP, kqueue, select) derive from
78 : this 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 remote endpoint 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 : 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 backend and cancels
134 : pending operations without closing the descriptor. The
135 : caller takes ownership.
136 :
137 : @return The native handle.
138 : */
139 : virtual native_handle_type release_socket() noexcept = 0;
140 :
141 : /** Request cancellation of pending asynchronous operations.
142 :
143 : All outstanding operations complete with operation_canceled error.
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 endpoint local_endpoint() const noexcept = 0;
177 :
178 : /// Return the cached remote endpoint.
179 : virtual 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 : tcp_socket& s_;
186 : endpoint endpoint_;
187 :
188 HIT 4515 : connect_awaitable(tcp_socket& s, endpoint ep) noexcept
189 9030 : : s_(s)
190 4515 : , endpoint_(ep)
191 : {
192 4515 : }
193 :
194 : std::coroutine_handle<>
195 4515 : dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
196 : {
197 4515 : 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 : tcp_socket& s_;
205 : wait_type w_;
206 :
207 64 : wait_awaitable(tcp_socket& s, wait_type w) noexcept : s_(s), w_(w) {}
208 :
209 : std::coroutine_handle<>
210 64 : dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
211 : {
212 64 : 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 : ~tcp_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 tcp_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>, tcp_socket>) &&
237 : capy::Executor<Ex>
238 1 : explicit tcp_socket(Ex const& ex) : tcp_socket(ex.context())
239 : {
240 1 : }
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 @p other is not referenced as a peer in any outstanding
250 : accept awaitable.
251 : @pre The execution context associated with @p other must
252 : outlive this socket.
253 : */
254 677 : tcp_socket(tcp_socket&& other) noexcept : io_object(std::move(other)) {}
255 :
256 : /** Move assignment operator.
257 :
258 : Closes any existing socket and transfers ownership.
259 :
260 : @param other The socket to move from.
261 :
262 : @pre No awaitables returned by either `*this` or @p other's
263 : methods exist.
264 : @pre Neither `*this` nor @p other is referenced as a peer in
265 : any outstanding accept awaitable.
266 : @pre The execution context associated with @p other must
267 : outlive this socket.
268 :
269 : @return Reference to this socket.
270 : */
271 23 : tcp_socket& operator=(tcp_socket&& other) noexcept
272 : {
273 23 : if (this != &other)
274 : {
275 23 : close();
276 23 : h_ = std::move(other.h_);
277 : }
278 23 : return *this;
279 : }
280 :
281 : tcp_socket(tcp_socket const&) = delete;
282 : tcp_socket& operator=(tcp_socket const&) = delete;
283 :
284 : /** Open the socket.
285 :
286 : Creates a TCP socket and associates it with the platform
287 : reactor (IOCP on Windows). Calling @ref connect on a closed
288 : socket opens it automatically with the endpoint's address family,
289 : so explicit `open()` is only needed when socket options must be
290 : set before connecting.
291 :
292 : Failures such as descriptor exhaustion are normal runtime
293 : conditions and are reported through the returned error code.
294 : Opening an already-open socket is a no-op that reports
295 : success.
296 :
297 : @param proto The protocol (IPv4 or IPv6). Defaults to
298 : `tcp::v4()`.
299 :
300 : @return The error code, empty on success.
301 : */
302 : [[nodiscard]] std::error_code open(tcp proto = tcp::v4()) noexcept;
303 :
304 : /** Bind the socket to a local endpoint.
305 :
306 : Associates the socket with a local address and port before
307 : connecting. Useful for multi-homed hosts or source-port
308 : pinning.
309 :
310 : @param ep The local endpoint to bind to.
311 :
312 : @return An error code indicating success or the reason for
313 : failure.
314 :
315 : @par Error Conditions
316 : @li `errc::address_in_use`: The endpoint is already in use.
317 : @li `errc::address_not_available`: The address is not
318 : available on any local interface.
319 : @li `errc::permission_denied`: Insufficient privileges to
320 : bind to the endpoint (e.g., privileged port).
321 :
322 : A closed socket reports `errc::bad_file_descriptor`.
323 : */
324 : [[nodiscard]] std::error_code bind(endpoint ep) noexcept;
325 :
326 : /** Close the socket.
327 :
328 : Releases socket resources. Any pending operations complete
329 : with `errc::operation_canceled`.
330 : */
331 : void close() noexcept;
332 :
333 : /** Check if the socket is open.
334 :
335 : @return `true` if the socket is open and ready for operations.
336 : */
337 28809 : bool is_open() const noexcept
338 : {
339 : #if BOOST_COROSIO_HAS_IOCP && !defined(BOOST_COROSIO_MRDOCS)
340 : return h_ && get().native_handle() != ~native_handle_type(0);
341 : #else
342 28809 : return h_ && get().native_handle() >= 0;
343 : #endif
344 : }
345 :
346 : /** Initiate an asynchronous connect operation.
347 :
348 : If the socket is not already open, it is opened automatically
349 : using the address family of @p ep (IPv4 or IPv6). If the socket
350 : is already open, the existing file descriptor is used as-is.
351 :
352 : The operation supports cancellation via `std::stop_token` through
353 : the affine awaitable protocol. If the associated stop token is
354 : triggered, the operation completes immediately with
355 : `errc::operation_canceled`.
356 :
357 : @param ep The remote endpoint to connect to.
358 :
359 : @return An awaitable that completes with `io_result<>`.
360 : Returns success (default error_code) on successful connection,
361 : or an error code on failure including:
362 : - connection_refused: No server listening at endpoint
363 : - timed_out: Connection attempt timed out
364 : - network_unreachable: No route to host
365 : - operation_canceled: Cancelled via stop_token or cancel().
366 : Check `ec == cond::canceled` for portable comparison.
367 :
368 : If the socket needs to be opened and the open fails, the
369 : awaitable completes immediately with that error.
370 :
371 : @par Preconditions
372 : This socket must outlive the returned awaitable.
373 :
374 : @par Example
375 : @par !example connect
376 : */
377 4515 : [[nodiscard]] auto connect(endpoint ep)
378 : {
379 4515 : connect_awaitable aw(*this, ep);
380 4515 : if (!is_open())
381 87 : aw.ec_ = open(ep.is_v6() ? tcp::v6() : tcp::v4());
382 4515 : return aw;
383 : }
384 :
385 : /** Wait for the socket to become ready in a given direction.
386 :
387 : Suspends until the socket is ready for the requested
388 : direction, or an error condition is reported. No bytes
389 : are transferred — useful for integrating with C libraries
390 : that own the I/O on a nonblocking fd and only need
391 : readiness notification (e.g. libpq async, libssh).
392 :
393 : The operation supports cancellation via `std::stop_token`
394 : through the affine awaitable protocol. If the associated
395 : stop token is triggered, the operation completes
396 : immediately with `errc::operation_canceled`.
397 :
398 : @param w The wait direction (read, write, or error).
399 :
400 : @return An awaitable that completes with `io_result<>`.
401 : On success, no bytes have been consumed from the
402 : stream; a subsequent `read_some` (for read waits)
403 : returns the available data.
404 :
405 : A closed socket completes with `errc::bad_file_descriptor`.
406 :
407 : @par Preconditions
408 : This socket must outlive the returned awaitable.
409 : */
410 64 : [[nodiscard]] auto wait(wait_type w)
411 : {
412 64 : return wait_awaitable(*this, w);
413 : }
414 :
415 : /** Cancel any pending asynchronous operations.
416 :
417 : All outstanding operations complete with `errc::operation_canceled`.
418 : Check `ec == cond::canceled` for portable comparison.
419 : */
420 : void cancel() noexcept;
421 :
422 : /** Get the native socket handle.
423 :
424 : Returns the underlying platform-specific socket descriptor.
425 : On POSIX systems this is an `int` file descriptor.
426 : On Windows this is a `SOCKET` handle.
427 :
428 : @return The native socket handle, or -1/INVALID_SOCKET if not open.
429 :
430 : @par Preconditions
431 : None. May be called on closed sockets.
432 : */
433 : native_handle_type native_handle() const noexcept;
434 :
435 : /** Assign an existing native socket to this object.
436 :
437 : Adopts a TCP socket created outside the library — received
438 : from another process, inherited, or made natively — and
439 : registers it with the backend. The socket must be a stream
440 : socket in the `AF_INET` or `AF_INET6` family. Adoption never
441 : alters the descriptor's flags or options: on POSIX the fd
442 : must already be non-blocking, and on Windows the socket must
443 : be overlapped-capable.
444 :
445 : If this object is already open, pending operations complete
446 : with `errc::operation_canceled` and the held socket is
447 : closed before the new one is adopted.
448 :
449 : @par Exception Safety
450 : Strong guarantee on validation failure: the object is
451 : unchanged. If backend registration fails, the object either
452 : retains its previous socket or is left closed, depending on
453 : the backend. In all failure cases the caller retains
454 : ownership of `fd`.
455 :
456 : @param fd The native socket to adopt. On success the object
457 : owns it and will close it.
458 :
459 : @return The error code, empty on success. Validation and
460 : registration failures are normal runtime conditions when
461 : adopting foreign descriptors.
462 : */
463 : [[nodiscard]] std::error_code assign(native_handle_type fd) noexcept;
464 :
465 : /** Release ownership of the native socket handle.
466 :
467 : Deregisters the socket from the backend and cancels pending
468 : operations without closing the descriptor. The caller takes
469 : ownership of the returned handle.
470 :
471 : @return The native handle.
472 :
473 : @throws std::system_error `errc::bad_file_descriptor` if the
474 : socket is not open.
475 :
476 : @post is_open() == false
477 : */
478 : native_handle_type release();
479 :
480 : /** Disable sends or receives on the socket.
481 :
482 : TCP connections are full-duplex: each direction (send and receive)
483 : operates independently. This function allows you to close one or
484 : both directions without destroying the socket.
485 :
486 : @li @ref shutdown_send sends a TCP FIN packet to the peer,
487 : signaling that you have no more data to send. You can still
488 : receive data until the peer also closes their send direction.
489 : This is the most common use case, typically called before
490 : close() to ensure graceful connection termination.
491 :
492 : @li @ref shutdown_receive disables reading on the socket. This
493 : does NOT send anything to the peer - they are not informed
494 : and may continue sending data. Subsequent reads will fail
495 : or return end-of-file. Incoming data may be discarded or
496 : buffered depending on the operating system.
497 :
498 : @li @ref shutdown_both combines both effects: sends a FIN and
499 : disables reading.
500 :
501 : When the peer shuts down their send direction (sends a FIN),
502 : subsequent read operations will complete with `capy::cond::eof`.
503 : Use the portable condition test rather than comparing error
504 : codes directly:
505 :
506 : @par !example shutdown
507 :
508 : Failures such as a peer that already disconnected are
509 : normal runtime conditions and are reported through the
510 : returned error code. A closed socket reports
511 : `errc::bad_file_descriptor`.
512 :
513 : @param what Determines what operations will no longer be allowed.
514 :
515 : @return The error code, empty on success.
516 : */
517 : [[nodiscard]] std::error_code shutdown(shutdown_type what) noexcept;
518 :
519 : /** Set a socket option.
520 :
521 : Applies a type-safe socket option to the underlying socket.
522 : The option type encodes the protocol level and option name.
523 :
524 : @par Example
525 : @par !example set_option
526 :
527 : @param opt The option to set.
528 :
529 : @throws std::system_error `errc::bad_file_descriptor` if the
530 : socket is not open; otherwise thrown on failure.
531 : */
532 : template<class Option>
533 288 : void set_option(Option const& opt)
534 : {
535 288 : if (!is_open())
536 2 : detail::throw_system_error(
537 4 : make_error_code(std::errc::bad_file_descriptor),
538 : "tcp_socket::set_option");
539 286 : std::error_code ec = get().set_option(
540 : Option::level(), Option::name(), opt.data(), opt.size());
541 286 : if (ec)
542 7 : detail::throw_system_error(ec, "tcp_socket::set_option");
543 279 : }
544 :
545 : /** Get a socket option.
546 :
547 : Retrieves the current value of a type-safe socket option.
548 :
549 : @par Example
550 : @par !example get_option
551 :
552 : @return The current option value.
553 :
554 : @throws std::system_error `errc::bad_file_descriptor` if the
555 : socket is not open; otherwise thrown on failure.
556 : */
557 : template<class Option>
558 97 : Option get_option() const
559 : {
560 97 : if (!is_open())
561 2 : detail::throw_system_error(
562 4 : make_error_code(std::errc::bad_file_descriptor),
563 : "tcp_socket::get_option");
564 95 : Option opt{};
565 95 : std::size_t sz = opt.size();
566 : std::error_code ec =
567 95 : get().get_option(Option::level(), Option::name(), opt.data(), &sz);
568 95 : if (ec)
569 7 : detail::throw_system_error(ec, "tcp_socket::get_option");
570 88 : opt.resize(sz);
571 88 : return opt;
572 : }
573 :
574 : /** Get the local endpoint of the socket.
575 :
576 : Returns the local address and port to which the socket is bound.
577 : For a connected socket, this is the local side of the connection.
578 : The endpoint is cached when the connection is established.
579 :
580 : @return The local endpoint, or a default endpoint (0.0.0.0:0) if
581 : the socket is not connected.
582 :
583 : @par Thread Safety
584 : The cached endpoint value is set during connect/accept completion
585 : and cleared during close(). This function may be called concurrently
586 : with I/O operations, but must not be called concurrently with
587 : connect(), accept(), or close().
588 : */
589 : endpoint local_endpoint() const noexcept;
590 :
591 : /** Get the remote endpoint of the socket.
592 :
593 : Returns the remote address and port to which the socket is connected.
594 : The endpoint is cached when the connection is established.
595 :
596 : @return The remote endpoint, or a default endpoint (0.0.0.0:0) if
597 : the socket is not connected.
598 :
599 : @par Thread Safety
600 : The cached endpoint value is set during connect/accept completion
601 : and cleared during close(). This function may be called concurrently
602 : with I/O operations, but must not be called concurrently with
603 : connect(), accept(), or close().
604 : */
605 : endpoint remote_endpoint() const noexcept;
606 :
607 : protected:
608 51 : tcp_socket() noexcept = default;
609 :
610 : explicit tcp_socket(handle h) noexcept : io_object(std::move(h)) {}
611 :
612 : private:
613 : friend class tcp_acceptor;
614 :
615 : /// Open the socket for the given protocol triple.
616 : [[nodiscard]] std::error_code
617 : open_for_family(int family, int type, int protocol) noexcept;
618 :
619 33461 : inline implementation& get() const noexcept
620 : {
621 33461 : return *static_cast<implementation*>(h_.get());
622 : }
623 : };
624 :
625 : } // namespace boost::corosio
626 :
627 : #endif
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