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/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 TCP socket for coroutine I/O.
41 :
42 : This class provides asynchronous TCP socket operations that return
43 : awaitable types. Each operation participates in the affine awaitable
44 : protocol, ensuring coroutines resume on the correct executor.
45 :
46 : The socket must be opened before performing I/O operations. Operations
47 : support cancellation through `std::stop_token` via the affine protocol,
48 : or explicitly through the `cancel()` member function.
49 :
50 : @par Thread Safety
51 : Distinct objects: Safe.@n
52 : Shared objects: Unsafe. A socket must not have concurrent operations
53 : of the same type (e.g., two simultaneous reads). One read and one
54 : write may be in flight simultaneously.
55 :
56 : @par Semantics
57 : Wraps the platform TCP/IP stack. Operations dispatch to
58 : OS socket APIs via the io_context reactor (epoll, IOCP,
59 : kqueue). Satisfies @ref capy::Stream.
60 :
61 : @par Example
62 : @code
63 : io_context ioc;
64 : tcp_socket s(ioc);
65 : s.open();
66 :
67 : // Using structured bindings
68 : auto [ec] = co_await s.connect(
69 : endpoint(ipv4_address::loopback(), 8080));
70 : if (ec)
71 : co_return;
72 :
73 : char buf[1024];
74 : auto [read_ec, n] = co_await s.read_some(
75 : capy::mutable_buffer(buf, sizeof(buf)));
76 : @endcode
77 : */
78 : class BOOST_COROSIO_DECL tcp_socket : public io_stream
79 : {
80 : public:
81 : using shutdown_type = corosio::shutdown_type;
82 : using enum corosio::shutdown_type;
83 :
84 : /** Define backend hooks for TCP socket operations.
85 :
86 : Platform backends (epoll, IOCP, kqueue, select) derive from
87 : this to implement socket I/O, connection, and option management.
88 : */
89 : struct implementation : io_stream::implementation
90 : {
91 : /** Initiate an asynchronous connect to the given endpoint.
92 :
93 : @param h Coroutine handle to resume on completion.
94 : @param ex Executor for dispatching the completion.
95 : @param ep The remote endpoint to connect to.
96 : @param token Stop token for cancellation.
97 : @param ec Output error code.
98 :
99 : @return Coroutine handle to resume immediately.
100 : */
101 : virtual std::coroutine_handle<> connect(
102 : std::coroutine_handle<> h,
103 : capy::executor_ref ex,
104 : endpoint ep,
105 : std::stop_token token,
106 : std::error_code* ec) = 0;
107 :
108 : /** Shut down the socket for the given direction(s).
109 :
110 : @param what The shutdown direction.
111 :
112 : @return Error code on failure, empty on success.
113 : */
114 : virtual std::error_code shutdown(shutdown_type what) noexcept = 0;
115 :
116 : /// Return the platform socket descriptor.
117 : virtual native_handle_type native_handle() const noexcept = 0;
118 :
119 : /** Request cancellation of pending asynchronous operations.
120 :
121 : All outstanding operations complete with operation_canceled error.
122 : Check `ec == cond::canceled` for portable comparison.
123 : */
124 : virtual void cancel() noexcept = 0;
125 :
126 : /** Set a socket option.
127 :
128 : @param level The protocol level (e.g. `SOL_SOCKET`).
129 : @param optname The option name (e.g. `SO_KEEPALIVE`).
130 : @param data Pointer to the option value.
131 : @param size Size of the option value in bytes.
132 : @return Error code on failure, empty on success.
133 : */
134 : virtual std::error_code set_option(
135 : int level,
136 : int optname,
137 : void const* data,
138 : std::size_t size) noexcept = 0;
139 :
140 : /** Get a socket option.
141 :
142 : @param level The protocol level (e.g. `SOL_SOCKET`).
143 : @param optname The option name (e.g. `SO_KEEPALIVE`).
144 : @param data Pointer to receive the option value.
145 : @param size On entry, the size of the buffer. On exit,
146 : the size of the option value.
147 : @return Error code on failure, empty on success.
148 : */
149 : virtual std::error_code
150 : get_option(int level, int optname, void* data, std::size_t* size)
151 : const noexcept = 0;
152 :
153 : /// Return the cached local endpoint.
154 : virtual endpoint local_endpoint() const noexcept = 0;
155 :
156 : /// Return the cached remote endpoint.
157 : virtual endpoint remote_endpoint() const noexcept = 0;
158 : };
159 :
160 : /// Represent the awaitable returned by @ref connect.
161 : struct connect_awaitable
162 : : detail::void_op_base<connect_awaitable>
163 : {
164 : tcp_socket& s_;
165 : endpoint endpoint_;
166 :
167 HIT 8514 : connect_awaitable(tcp_socket& s, endpoint ep) noexcept
168 8514 : : s_(s), endpoint_(ep) {}
169 :
170 8514 : std::coroutine_handle<> dispatch(
171 : std::coroutine_handle<> h, capy::executor_ref ex) const
172 : {
173 8514 : return s_.get().connect(h, ex, endpoint_, token_, &ec_);
174 : }
175 : };
176 :
177 : public:
178 : /** Destructor.
179 :
180 : Closes the socket if open, cancelling any pending operations.
181 : */
182 : ~tcp_socket() override;
183 :
184 : /** Construct a socket from an execution context.
185 :
186 : @param ctx The execution context that will own this socket.
187 : */
188 : explicit tcp_socket(capy::execution_context& ctx);
189 :
190 : /** Construct a socket from an executor.
191 :
192 : The socket is associated with the executor's context.
193 :
194 : @param ex The executor whose context will own the socket.
195 : */
196 : template<class Ex>
197 : requires(!std::same_as<std::remove_cvref_t<Ex>, tcp_socket>) &&
198 : capy::Executor<Ex>
199 : explicit tcp_socket(Ex const& ex) : tcp_socket(ex.context())
200 : {
201 : }
202 :
203 : /** Move constructor.
204 :
205 : Transfers ownership of the socket resources.
206 :
207 : @param other The socket to move from.
208 :
209 : @pre No awaitables returned by @p other's methods exist.
210 : @pre @p other is not referenced as a peer in any outstanding
211 : accept awaitable.
212 : @pre The execution context associated with @p other must
213 : outlive this socket.
214 : */
215 176 : tcp_socket(tcp_socket&& other) noexcept : io_object(std::move(other)) {}
216 :
217 : /** Move assignment operator.
218 :
219 : Closes any existing socket and transfers ownership.
220 :
221 : @param other The socket to move from.
222 :
223 : @pre No awaitables returned by either `*this` or @p other's
224 : methods exist.
225 : @pre Neither `*this` nor @p other is referenced as a peer in
226 : any outstanding accept awaitable.
227 : @pre The execution context associated with @p other must
228 : outlive this socket.
229 :
230 : @return Reference to this socket.
231 : */
232 10 : tcp_socket& operator=(tcp_socket&& other) noexcept
233 : {
234 10 : if (this != &other)
235 : {
236 10 : close();
237 10 : h_ = std::move(other.h_);
238 : }
239 10 : return *this;
240 : }
241 :
242 : tcp_socket(tcp_socket const&) = delete;
243 : tcp_socket& operator=(tcp_socket const&) = delete;
244 :
245 : /** Open the socket.
246 :
247 : Creates a TCP socket and associates it with the platform
248 : reactor (IOCP on Windows). Calling @ref connect on a closed
249 : socket opens it automatically with the endpoint's address family,
250 : so explicit `open()` is only needed when socket options must be
251 : set before connecting.
252 :
253 : @param proto The protocol (IPv4 or IPv6). Defaults to
254 : `tcp::v4()`.
255 :
256 : @throws std::system_error on failure.
257 : */
258 : void open(tcp proto = tcp::v4());
259 :
260 : /** Bind the socket to a local endpoint.
261 :
262 : Associates the socket with a local address and port before
263 : connecting. Useful for multi-homed hosts or source-port
264 : pinning.
265 :
266 : @param ep The local endpoint to bind to.
267 :
268 : @return An error code indicating success or the reason for
269 : failure.
270 :
271 : @par Error Conditions
272 : @li `errc::address_in_use`: The endpoint is already in use.
273 : @li `errc::address_not_available`: The address is not
274 : available on any local interface.
275 : @li `errc::permission_denied`: Insufficient privileges to
276 : bind to the endpoint (e.g., privileged port).
277 :
278 : @throws std::logic_error if the socket is not open.
279 : */
280 : [[nodiscard]] std::error_code bind(endpoint ep);
281 :
282 : /** Close the socket.
283 :
284 : Releases socket resources. Any pending operations complete
285 : with `errc::operation_canceled`.
286 : */
287 : void close();
288 :
289 : /** Check if the socket is open.
290 :
291 : @return `true` if the socket is open and ready for operations.
292 : */
293 51961 : bool is_open() const noexcept
294 : {
295 : #if BOOST_COROSIO_HAS_IOCP && !defined(BOOST_COROSIO_MRDOCS)
296 : return h_ && get().native_handle() != ~native_handle_type(0);
297 : #else
298 51961 : return h_ && get().native_handle() >= 0;
299 : #endif
300 : }
301 :
302 : /** Initiate an asynchronous connect operation.
303 :
304 : If the socket is not already open, it is opened automatically
305 : using the address family of @p ep (IPv4 or IPv6). If the socket
306 : is already open, the existing file descriptor is used as-is.
307 :
308 : The operation supports cancellation via `std::stop_token` through
309 : the affine awaitable protocol. If the associated stop token is
310 : triggered, the operation completes immediately with
311 : `errc::operation_canceled`.
312 :
313 : @param ep The remote endpoint to connect to.
314 :
315 : @return An awaitable that completes with `io_result<>`.
316 : Returns success (default error_code) on successful connection,
317 : or an error code on failure including:
318 : - connection_refused: No server listening at endpoint
319 : - timed_out: Connection attempt timed out
320 : - network_unreachable: No route to host
321 : - operation_canceled: Cancelled via stop_token or cancel().
322 : Check `ec == cond::canceled` for portable comparison.
323 :
324 : @throws std::system_error if the socket needs to be opened
325 : and the open fails.
326 :
327 : @par Preconditions
328 : This socket must outlive the returned awaitable.
329 :
330 : @par Example
331 : @code
332 : // Socket opened automatically with correct address family:
333 : auto [ec] = co_await s.connect(endpoint);
334 : if (ec) { ... }
335 : @endcode
336 : */
337 8514 : auto connect(endpoint ep)
338 : {
339 8514 : if (!is_open())
340 16 : open(ep.is_v6() ? tcp::v6() : tcp::v4());
341 8514 : return connect_awaitable(*this, ep);
342 : }
343 :
344 : /** Cancel any pending asynchronous operations.
345 :
346 : All outstanding operations complete with `errc::operation_canceled`.
347 : Check `ec == cond::canceled` for portable comparison.
348 : */
349 : void cancel();
350 :
351 : /** Get the native socket handle.
352 :
353 : Returns the underlying platform-specific socket descriptor.
354 : On POSIX systems this is an `int` file descriptor.
355 : On Windows this is a `SOCKET` handle.
356 :
357 : @return The native socket handle, or -1/INVALID_SOCKET if not open.
358 :
359 : @par Preconditions
360 : None. May be called on closed sockets.
361 : */
362 : native_handle_type native_handle() const noexcept;
363 :
364 : /** Disable sends or receives on the socket.
365 :
366 : TCP connections are full-duplex: each direction (send and receive)
367 : operates independently. This function allows you to close one or
368 : both directions without destroying the socket.
369 :
370 : @li @ref shutdown_send sends a TCP FIN packet to the peer,
371 : signaling that you have no more data to send. You can still
372 : receive data until the peer also closes their send direction.
373 : This is the most common use case, typically called before
374 : close() to ensure graceful connection termination.
375 :
376 : @li @ref shutdown_receive disables reading on the socket. This
377 : does NOT send anything to the peer - they are not informed
378 : and may continue sending data. Subsequent reads will fail
379 : or return end-of-file. Incoming data may be discarded or
380 : buffered depending on the operating system.
381 :
382 : @li @ref shutdown_both combines both effects: sends a FIN and
383 : disables reading.
384 :
385 : When the peer shuts down their send direction (sends a FIN),
386 : subsequent read operations will complete with `capy::cond::eof`.
387 : Use the portable condition test rather than comparing error
388 : codes directly:
389 :
390 : @code
391 : auto [ec, n] = co_await sock.read_some(buffer);
392 : if (ec == capy::cond::eof)
393 : {
394 : // Peer closed their send direction
395 : }
396 : @endcode
397 :
398 : Any error from the underlying system call is silently discarded
399 : because it is unlikely to be helpful.
400 :
401 : @param what Determines what operations will no longer be allowed.
402 : */
403 : void shutdown(shutdown_type what);
404 :
405 : /** Set a socket option.
406 :
407 : Applies a type-safe socket option to the underlying socket.
408 : The option type encodes the protocol level and option name.
409 :
410 : @par Example
411 : @code
412 : sock.set_option( socket_option::no_delay( true ) );
413 : sock.set_option( socket_option::receive_buffer_size( 65536 ) );
414 : @endcode
415 :
416 : @param opt The option to set.
417 :
418 : @throws std::logic_error if the socket is not open.
419 : @throws std::system_error on failure.
420 : */
421 : template<class Option>
422 60 : void set_option(Option const& opt)
423 : {
424 60 : if (!is_open())
425 MIS 0 : detail::throw_logic_error("set_option: socket not open");
426 HIT 60 : std::error_code ec = get().set_option(
427 : Option::level(), Option::name(), opt.data(), opt.size());
428 60 : if (ec)
429 MIS 0 : detail::throw_system_error(ec, "tcp_socket::set_option");
430 HIT 60 : }
431 :
432 : /** Get a socket option.
433 :
434 : Retrieves the current value of a type-safe socket option.
435 :
436 : @par Example
437 : @code
438 : auto nd = sock.get_option<socket_option::no_delay>();
439 : if ( nd.value() )
440 : // Nagle's algorithm is disabled
441 : @endcode
442 :
443 : @return The current option value.
444 :
445 : @throws std::logic_error if the socket is not open.
446 : @throws std::system_error on failure.
447 : */
448 : template<class Option>
449 62 : Option get_option() const
450 : {
451 62 : if (!is_open())
452 MIS 0 : detail::throw_logic_error("get_option: socket not open");
453 HIT 62 : Option opt{};
454 62 : std::size_t sz = opt.size();
455 : std::error_code ec =
456 62 : get().get_option(Option::level(), Option::name(), opt.data(), &sz);
457 62 : if (ec)
458 MIS 0 : detail::throw_system_error(ec, "tcp_socket::get_option");
459 HIT 62 : opt.resize(sz);
460 62 : return opt;
461 : }
462 :
463 : /** Get the local endpoint of the socket.
464 :
465 : Returns the local address and port to which the socket is bound.
466 : For a connected socket, this is the local side of the connection.
467 : The endpoint is cached when the connection is established.
468 :
469 : @return The local endpoint, or a default endpoint (0.0.0.0:0) if
470 : the socket is not connected.
471 :
472 : @par Thread Safety
473 : The cached endpoint value is set during connect/accept completion
474 : and cleared during close(). This function may be called concurrently
475 : with I/O operations, but must not be called concurrently with
476 : connect(), accept(), or close().
477 : */
478 : endpoint local_endpoint() const noexcept;
479 :
480 : /** Get the remote endpoint of the socket.
481 :
482 : Returns the remote address and port to which the socket is connected.
483 : The endpoint is cached when the connection is established.
484 :
485 : @return The remote endpoint, or a default endpoint (0.0.0.0:0) if
486 : the socket is not connected.
487 :
488 : @par Thread Safety
489 : The cached endpoint value is set during connect/accept completion
490 : and cleared during close(). This function may be called concurrently
491 : with I/O operations, but must not be called concurrently with
492 : connect(), accept(), or close().
493 : */
494 : endpoint remote_endpoint() const noexcept;
495 :
496 : protected:
497 10 : tcp_socket() noexcept = default;
498 :
499 : explicit tcp_socket(handle h) noexcept : io_object(std::move(h)) {}
500 :
501 : private:
502 : friend class tcp_acceptor;
503 :
504 : /// Open the socket for the given protocol triple.
505 : void open_for_family(int family, int type, int protocol);
506 :
507 60677 : inline implementation& get() const noexcept
508 : {
509 60677 : return *static_cast<implementation*>(h_.get());
510 : }
511 : };
512 :
513 : } // namespace boost::corosio
514 :
515 : #endif
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