TLA Line data Source code
1 : //
2 : // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3 : // Copyright (c) 2026 Steve Gerbino
4 : //
5 : // Distributed under the Boost Software License, Version 1.0. (See accompanying
6 : // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7 : //
8 : // Official repository: https://github.com/cppalliance/corosio
9 : //
10 :
11 : #ifndef BOOST_COROSIO_TCP_SOCKET_HPP
12 : #define BOOST_COROSIO_TCP_SOCKET_HPP
13 :
14 : #include <boost/corosio/detail/config.hpp>
15 : #include <boost/corosio/detail/platform.hpp>
16 : #include <boost/corosio/detail/except.hpp>
17 : #include <boost/corosio/detail/native_handle.hpp>
18 : #include <boost/corosio/detail/op_base.hpp>
19 : #include <boost/corosio/io/io_stream.hpp>
20 : #include <boost/capy/io_result.hpp>
21 : #include <boost/corosio/detail/buffer_param.hpp>
22 : #include <boost/corosio/endpoint.hpp>
23 : #include <boost/corosio/shutdown_type.hpp>
24 : #include <boost/corosio/tcp.hpp>
25 : #include <boost/corosio/wait_type.hpp>
26 : #include <boost/capy/ex/executor_ref.hpp>
27 : #include <boost/capy/ex/execution_context.hpp>
28 : #include <boost/capy/ex/io_env.hpp>
29 : #include <boost/capy/concept/executor.hpp>
30 :
31 : #include <system_error>
32 :
33 : #include <concepts>
34 : #include <coroutine>
35 : #include <cstddef>
36 : #include <stop_token>
37 : #include <type_traits>
38 :
39 : namespace boost::corosio {
40 :
41 : /** An asynchronous TCP socket for coroutine I/O.
42 :
43 : This class provides asynchronous TCP socket operations that return
44 : awaitable types. Each operation participates in the affine awaitable
45 : protocol, ensuring coroutines resume on the correct executor.
46 :
47 : The socket must be opened before performing I/O operations. Operations
48 : support cancellation through `std::stop_token` via the affine protocol,
49 : or explicitly through the `cancel()` member function.
50 :
51 : @par Thread Safety
52 : Distinct objects: Safe.@n
53 : Shared objects: Unsafe. A socket must not have concurrent operations
54 : of the same type (e.g., two simultaneous reads). One read and one
55 : write may be in flight simultaneously.
56 :
57 : @par Semantics
58 : Wraps the platform TCP/IP stack. Operations dispatch to
59 : OS socket APIs via the io_context reactor (epoll, IOCP,
60 : kqueue). Satisfies @ref capy::Stream.
61 :
62 : @par Example
63 : @code
64 : io_context ioc;
65 : tcp_socket s(ioc);
66 : s.open();
67 :
68 : // Using structured bindings
69 : auto [ec] = co_await s.connect(
70 : endpoint(ipv4_address::loopback(), 8080));
71 : if (ec)
72 : co_return;
73 :
74 : char buf[1024];
75 : auto [read_ec, n] = co_await s.read_some(
76 : capy::mutable_buffer(buf, sizeof(buf)));
77 : @endcode
78 : */
79 : class BOOST_COROSIO_DECL tcp_socket : public io_stream
80 : {
81 : public:
82 : /// The endpoint type used by this socket.
83 : using endpoint_type = corosio::endpoint;
84 :
85 : using shutdown_type = corosio::shutdown_type;
86 : using enum corosio::shutdown_type;
87 :
88 : /** Define backend hooks for TCP socket operations.
89 :
90 : Platform backends (epoll, IOCP, kqueue, select) derive from
91 : this to implement socket I/O, connection, and option management.
92 : */
93 : struct implementation : io_stream::implementation
94 : {
95 : /** Initiate an asynchronous connect to the given endpoint.
96 :
97 : @param h Coroutine handle to resume on completion.
98 : @param ex Executor for dispatching the completion.
99 : @param ep The remote endpoint to connect to.
100 : @param token Stop token for cancellation.
101 : @param ec Output error code.
102 :
103 : @return Coroutine handle to resume immediately.
104 : */
105 : virtual std::coroutine_handle<> connect(
106 : std::coroutine_handle<> h,
107 : capy::executor_ref ex,
108 : endpoint ep,
109 : std::stop_token token,
110 : std::error_code* ec) = 0;
111 :
112 : /** Initiate an asynchronous wait for socket readiness.
113 :
114 : Completes when the socket becomes ready for the
115 : specified direction, or an error condition is
116 : reported. No bytes are transferred.
117 :
118 : @param h Coroutine handle to resume on completion.
119 : @param ex Executor for dispatching the completion.
120 : @param w The direction to wait on.
121 : @param token Stop token for cancellation.
122 : @param ec Output error code.
123 :
124 : @return Coroutine handle to resume immediately.
125 : */
126 : virtual std::coroutine_handle<> wait(
127 : std::coroutine_handle<> h,
128 : capy::executor_ref ex,
129 : wait_type w,
130 : std::stop_token token,
131 : std::error_code* ec) = 0;
132 :
133 : /** Shut down the socket for the given direction(s).
134 :
135 : @param what The shutdown direction.
136 :
137 : @return Error code on failure, empty on success.
138 : */
139 : virtual std::error_code shutdown(shutdown_type what) noexcept = 0;
140 :
141 : /// Return the platform socket descriptor.
142 : virtual native_handle_type native_handle() const noexcept = 0;
143 :
144 : /** Request cancellation of pending asynchronous operations.
145 :
146 : All outstanding operations complete with operation_canceled error.
147 : Check `ec == cond::canceled` for portable comparison.
148 : */
149 : virtual void cancel() noexcept = 0;
150 :
151 : /** Set a socket option.
152 :
153 : @param level The protocol level (e.g. `SOL_SOCKET`).
154 : @param optname The option name (e.g. `SO_KEEPALIVE`).
155 : @param data Pointer to the option value.
156 : @param size Size of the option value in bytes.
157 : @return Error code on failure, empty on success.
158 : */
159 : virtual std::error_code set_option(
160 : int level,
161 : int optname,
162 : void const* data,
163 : std::size_t size) noexcept = 0;
164 :
165 : /** Get a socket option.
166 :
167 : @param level The protocol level (e.g. `SOL_SOCKET`).
168 : @param optname The option name (e.g. `SO_KEEPALIVE`).
169 : @param data Pointer to receive the option value.
170 : @param size On entry, the size of the buffer. On exit,
171 : the size of the option value.
172 : @return Error code on failure, empty on success.
173 : */
174 : virtual std::error_code
175 : get_option(int level, int optname, void* data, std::size_t* size)
176 : const noexcept = 0;
177 :
178 : /// Return the cached local endpoint.
179 : virtual endpoint local_endpoint() const noexcept = 0;
180 :
181 : /// Return the cached remote endpoint.
182 : virtual endpoint remote_endpoint() const noexcept = 0;
183 : };
184 :
185 : /// Represent the awaitable returned by @ref connect.
186 : struct connect_awaitable
187 : : detail::void_op_base<connect_awaitable>
188 : {
189 : tcp_socket& s_;
190 : endpoint endpoint_;
191 :
192 HIT 8428 : connect_awaitable(tcp_socket& s, endpoint ep) noexcept
193 8428 : : s_(s), endpoint_(ep) {}
194 :
195 8428 : std::coroutine_handle<> dispatch(
196 : std::coroutine_handle<> h, capy::executor_ref ex) const
197 : {
198 8428 : return s_.get().connect(h, ex, endpoint_, token_, &ec_);
199 : }
200 : };
201 :
202 : /// Represent the awaitable returned by @ref wait.
203 : struct wait_awaitable
204 : : detail::void_op_base<wait_awaitable>
205 : {
206 : tcp_socket& s_;
207 : wait_type w_;
208 :
209 6 : wait_awaitable(tcp_socket& s, wait_type w) noexcept
210 6 : : s_(s), w_(w) {}
211 :
212 6 : std::coroutine_handle<> dispatch(
213 : std::coroutine_handle<> h, capy::executor_ref ex) const
214 : {
215 6 : return s_.get().wait(h, ex, w_, token_, &ec_);
216 : }
217 : };
218 :
219 : public:
220 : /** Destructor.
221 :
222 : Closes the socket if open, cancelling any pending operations.
223 : */
224 : ~tcp_socket() override;
225 :
226 : /** Construct a socket from an execution context.
227 :
228 : @param ctx The execution context that will own this socket.
229 : */
230 : explicit tcp_socket(capy::execution_context& ctx);
231 :
232 : /** Construct a socket from an executor.
233 :
234 : The socket is associated with the executor's context.
235 :
236 : @param ex The executor whose context will own the socket.
237 : */
238 : template<class Ex>
239 : requires(!std::same_as<std::remove_cvref_t<Ex>, tcp_socket>) &&
240 : capy::Executor<Ex>
241 : explicit tcp_socket(Ex const& ex) : tcp_socket(ex.context())
242 : {
243 : }
244 :
245 : /** Move constructor.
246 :
247 : Transfers ownership of the socket resources.
248 :
249 : @param other The socket to move from.
250 :
251 : @pre No awaitables returned by @p other's methods exist.
252 : @pre @p other is not referenced as a peer in any outstanding
253 : accept awaitable.
254 : @pre The execution context associated with @p other must
255 : outlive this socket.
256 : */
257 188 : tcp_socket(tcp_socket&& other) noexcept : io_object(std::move(other)) {}
258 :
259 : /** Move assignment operator.
260 :
261 : Closes any existing socket and transfers ownership.
262 :
263 : @param other The socket to move from.
264 :
265 : @pre No awaitables returned by either `*this` or @p other's
266 : methods exist.
267 : @pre Neither `*this` nor @p other is referenced as a peer in
268 : any outstanding accept awaitable.
269 : @pre The execution context associated with @p other must
270 : outlive this socket.
271 :
272 : @return Reference to this socket.
273 : */
274 10 : tcp_socket& operator=(tcp_socket&& other) noexcept
275 : {
276 10 : if (this != &other)
277 : {
278 10 : close();
279 10 : h_ = std::move(other.h_);
280 : }
281 10 : return *this;
282 : }
283 :
284 : tcp_socket(tcp_socket const&) = delete;
285 : tcp_socket& operator=(tcp_socket const&) = delete;
286 :
287 : /** Open the socket.
288 :
289 : Creates a TCP socket and associates it with the platform
290 : reactor (IOCP on Windows). Calling @ref connect on a closed
291 : socket opens it automatically with the endpoint's address family,
292 : so explicit `open()` is only needed when socket options must be
293 : set before connecting.
294 :
295 : @param proto The protocol (IPv4 or IPv6). Defaults to
296 : `tcp::v4()`.
297 :
298 : @throws std::system_error on failure.
299 : */
300 : void open(tcp proto = tcp::v4());
301 :
302 : /** Bind the socket to a local endpoint.
303 :
304 : Associates the socket with a local address and port before
305 : connecting. Useful for multi-homed hosts or source-port
306 : pinning.
307 :
308 : @param ep The local endpoint to bind to.
309 :
310 : @return An error code indicating success or the reason for
311 : failure.
312 :
313 : @par Error Conditions
314 : @li `errc::address_in_use`: The endpoint is already in use.
315 : @li `errc::address_not_available`: The address is not
316 : available on any local interface.
317 : @li `errc::permission_denied`: Insufficient privileges to
318 : bind to the endpoint (e.g., privileged port).
319 :
320 : @throws std::logic_error if the socket is not open.
321 : */
322 : [[nodiscard]] std::error_code bind(endpoint ep);
323 :
324 : /** Close the socket.
325 :
326 : Releases socket resources. Any pending operations complete
327 : with `errc::operation_canceled`.
328 : */
329 : void close();
330 :
331 : /** Check if the socket is open.
332 :
333 : @return `true` if the socket is open and ready for operations.
334 : */
335 51431 : bool is_open() const noexcept
336 : {
337 : #if BOOST_COROSIO_HAS_IOCP && !defined(BOOST_COROSIO_MRDOCS)
338 : return h_ && get().native_handle() != ~native_handle_type(0);
339 : #else
340 51431 : return h_ && get().native_handle() >= 0;
341 : #endif
342 : }
343 :
344 : /** Initiate an asynchronous connect operation.
345 :
346 : If the socket is not already open, it is opened automatically
347 : using the address family of @p ep (IPv4 or IPv6). If the socket
348 : is already open, the existing file descriptor is used as-is.
349 :
350 : The operation supports cancellation via `std::stop_token` through
351 : the affine awaitable protocol. If the associated stop token is
352 : triggered, the operation completes immediately with
353 : `errc::operation_canceled`.
354 :
355 : @param ep The remote endpoint to connect to.
356 :
357 : @return An awaitable that completes with `io_result<>`.
358 : Returns success (default error_code) on successful connection,
359 : or an error code on failure including:
360 : - connection_refused: No server listening at endpoint
361 : - timed_out: Connection attempt timed out
362 : - network_unreachable: No route to host
363 : - operation_canceled: Cancelled via stop_token or cancel().
364 : Check `ec == cond::canceled` for portable comparison.
365 :
366 : @throws std::system_error if the socket needs to be opened
367 : and the open fails.
368 :
369 : @par Preconditions
370 : This socket must outlive the returned awaitable.
371 :
372 : @par Example
373 : @code
374 : // Socket opened automatically with correct address family:
375 : auto [ec] = co_await s.connect(endpoint);
376 : if (ec) { ... }
377 : @endcode
378 : */
379 8428 : auto connect(endpoint ep)
380 : {
381 8428 : if (!is_open())
382 40 : open(ep.is_v6() ? tcp::v6() : tcp::v4());
383 8428 : return connect_awaitable(*this, ep);
384 : }
385 :
386 : /** Wait for the socket to become ready in a given direction.
387 :
388 : Suspends until the socket is ready for the requested
389 : direction, or an error condition is reported. No bytes
390 : are transferred — useful for integrating with C libraries
391 : that own the I/O on a nonblocking fd and only need
392 : readiness notification (e.g. libpq async, libssh).
393 :
394 : The operation supports cancellation via `std::stop_token`
395 : through the affine awaitable protocol. If the associated
396 : stop token is triggered, the operation completes
397 : immediately with `errc::operation_canceled`.
398 :
399 : @param w The wait direction (read, write, or error).
400 :
401 : @return An awaitable that completes with `io_result<>`.
402 : On success, no bytes have been consumed from the
403 : stream; a subsequent `read_some` (for read waits)
404 : returns the available data.
405 :
406 : @par Preconditions
407 : The socket must be open. This socket must outlive the
408 : returned awaitable.
409 : */
410 6 : [[nodiscard]] auto wait(wait_type w)
411 : {
412 6 : 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();
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 : /** Disable sends or receives on the socket.
436 :
437 : TCP connections are full-duplex: each direction (send and receive)
438 : operates independently. This function allows you to close one or
439 : both directions without destroying the socket.
440 :
441 : @li @ref shutdown_send sends a TCP FIN packet to the peer,
442 : signaling that you have no more data to send. You can still
443 : receive data until the peer also closes their send direction.
444 : This is the most common use case, typically called before
445 : close() to ensure graceful connection termination.
446 :
447 : @li @ref shutdown_receive disables reading on the socket. This
448 : does NOT send anything to the peer - they are not informed
449 : and may continue sending data. Subsequent reads will fail
450 : or return end-of-file. Incoming data may be discarded or
451 : buffered depending on the operating system.
452 :
453 : @li @ref shutdown_both combines both effects: sends a FIN and
454 : disables reading.
455 :
456 : When the peer shuts down their send direction (sends a FIN),
457 : subsequent read operations will complete with `capy::cond::eof`.
458 : Use the portable condition test rather than comparing error
459 : codes directly:
460 :
461 : @code
462 : auto [ec, n] = co_await sock.read_some(buffer);
463 : if (ec == capy::cond::eof)
464 : {
465 : // Peer closed their send direction
466 : }
467 : @endcode
468 :
469 : Any error from the underlying system call is silently discarded
470 : because it is unlikely to be helpful.
471 :
472 : @param what Determines what operations will no longer be allowed.
473 : */
474 : void shutdown(shutdown_type what);
475 :
476 : /** Set a socket option.
477 :
478 : Applies a type-safe socket option to the underlying socket.
479 : The option type encodes the protocol level and option name.
480 :
481 : @par Example
482 : @code
483 : sock.set_option( socket_option::no_delay( true ) );
484 : sock.set_option( socket_option::receive_buffer_size( 65536 ) );
485 : @endcode
486 :
487 : @param opt The option to set.
488 :
489 : @throws std::logic_error if the socket is not open.
490 : @throws std::system_error on failure.
491 : */
492 : template<class Option>
493 72 : void set_option(Option const& opt)
494 : {
495 72 : if (!is_open())
496 MIS 0 : detail::throw_logic_error("set_option: socket not open");
497 HIT 72 : std::error_code ec = get().set_option(
498 : Option::level(), Option::name(), opt.data(), opt.size());
499 72 : if (ec)
500 MIS 0 : detail::throw_system_error(ec, "tcp_socket::set_option");
501 HIT 72 : }
502 :
503 : /** Get a socket option.
504 :
505 : Retrieves the current value of a type-safe socket option.
506 :
507 : @par Example
508 : @code
509 : auto nd = sock.get_option<socket_option::no_delay>();
510 : if ( nd.value() )
511 : // Nagle's algorithm is disabled
512 : @endcode
513 :
514 : @return The current option value.
515 :
516 : @throws std::logic_error if the socket is not open.
517 : @throws std::system_error on failure.
518 : */
519 : template<class Option>
520 62 : Option get_option() const
521 : {
522 62 : if (!is_open())
523 MIS 0 : detail::throw_logic_error("get_option: socket not open");
524 HIT 62 : Option opt{};
525 62 : std::size_t sz = opt.size();
526 : std::error_code ec =
527 62 : get().get_option(Option::level(), Option::name(), opt.data(), &sz);
528 62 : if (ec)
529 MIS 0 : detail::throw_system_error(ec, "tcp_socket::get_option");
530 HIT 62 : opt.resize(sz);
531 62 : return opt;
532 : }
533 :
534 : /** Get the local endpoint of the socket.
535 :
536 : Returns the local address and port to which the socket is bound.
537 : For a connected socket, this is the local side of the connection.
538 : The endpoint is cached when the connection is established.
539 :
540 : @return The local endpoint, or a default endpoint (0.0.0.0:0) if
541 : the socket is not connected.
542 :
543 : @par Thread Safety
544 : The cached endpoint value is set during connect/accept completion
545 : and cleared during close(). This function may be called concurrently
546 : with I/O operations, but must not be called concurrently with
547 : connect(), accept(), or close().
548 : */
549 : endpoint local_endpoint() const noexcept;
550 :
551 : /** Get the remote endpoint of the socket.
552 :
553 : Returns the remote address and port to which the socket is connected.
554 : The endpoint is cached when the connection is established.
555 :
556 : @return The remote endpoint, or a default endpoint (0.0.0.0:0) if
557 : the socket is not connected.
558 :
559 : @par Thread Safety
560 : The cached endpoint value is set during connect/accept completion
561 : and cleared during close(). This function may be called concurrently
562 : with I/O operations, but must not be called concurrently with
563 : connect(), accept(), or close().
564 : */
565 : endpoint remote_endpoint() const noexcept;
566 :
567 : protected:
568 10 : tcp_socket() noexcept = default;
569 :
570 : explicit tcp_socket(handle h) noexcept : io_object(std::move(h)) {}
571 :
572 : private:
573 : friend class tcp_acceptor;
574 :
575 : /// Open the socket for the given protocol triple.
576 : void open_for_family(int family, int type, int protocol);
577 :
578 60073 : inline implementation& get() const noexcept
579 : {
580 60073 : return *static_cast<implementation*>(h_.get());
581 : }
582 : };
583 :
584 : } // namespace boost::corosio
585 :
586 : #endif
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