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/io/io_stream.hpp>
18 : #include <boost/capy/io_result.hpp>
19 : #include <boost/corosio/io_buffer_param.hpp>
20 : #include <boost/corosio/endpoint.hpp>
21 : #include <boost/capy/ex/executor_ref.hpp>
22 : #include <boost/capy/ex/execution_context.hpp>
23 : #include <boost/capy/ex/io_env.hpp>
24 : #include <boost/capy/concept/executor.hpp>
25 :
26 : #include <system_error>
27 :
28 : #include <concepts>
29 : #include <coroutine>
30 : #include <cstddef>
31 : #include <memory>
32 : #include <stop_token>
33 : #include <type_traits>
34 :
35 : namespace boost::corosio {
36 :
37 : #if BOOST_COROSIO_HAS_IOCP
38 : using native_handle_type = std::uintptr_t; // SOCKET
39 : #else
40 : using native_handle_type = int;
41 : #endif
42 :
43 : /** An asynchronous TCP socket for coroutine I/O.
44 :
45 : This class provides asynchronous TCP socket operations that return
46 : awaitable types. Each operation participates in the affine awaitable
47 : protocol, ensuring coroutines resume on the correct executor.
48 :
49 : The socket must be opened before performing I/O operations. Operations
50 : support cancellation through `std::stop_token` via the affine protocol,
51 : or explicitly through the `cancel()` member function.
52 :
53 : @par Thread Safety
54 : Distinct objects: Safe.@n
55 : Shared objects: Unsafe. A socket must not have concurrent operations
56 : of the same type (e.g., two simultaneous reads). One read and one
57 : write may be in flight simultaneously.
58 :
59 : @par Semantics
60 : Wraps the platform TCP/IP stack. Operations dispatch to
61 : OS socket APIs via the io_context reactor (epoll, IOCP,
62 : kqueue). Satisfies @ref capy::Stream.
63 :
64 : @par Example
65 : @code
66 : io_context ioc;
67 : tcp_socket s(ioc);
68 : s.open();
69 :
70 : // Using structured bindings
71 : auto [ec] = co_await s.connect(
72 : endpoint(ipv4_address::loopback(), 8080));
73 : if (ec)
74 : co_return;
75 :
76 : char buf[1024];
77 : auto [read_ec, n] = co_await s.read_some(
78 : capy::mutable_buffer(buf, sizeof(buf)));
79 : @endcode
80 : */
81 : class BOOST_COROSIO_DECL tcp_socket : public io_stream
82 : {
83 : public:
84 : /** Different ways a socket may be shutdown. */
85 : enum shutdown_type
86 : {
87 : shutdown_receive,
88 : shutdown_send,
89 : shutdown_both
90 : };
91 :
92 : /** Options for SO_LINGER socket option. */
93 : struct linger_options
94 : {
95 : bool enabled = false;
96 : int timeout = 0; // seconds
97 : };
98 :
99 : struct implementation : io_stream::implementation
100 : {
101 : virtual std::coroutine_handle<> connect(
102 : std::coroutine_handle<>,
103 : capy::executor_ref,
104 : endpoint,
105 : std::stop_token,
106 : std::error_code*) = 0;
107 :
108 : virtual std::error_code shutdown(shutdown_type) noexcept = 0;
109 :
110 : virtual native_handle_type native_handle() const noexcept = 0;
111 :
112 : /** Request cancellation of pending asynchronous operations.
113 :
114 : All outstanding operations complete with operation_canceled error.
115 : Check `ec == cond::canceled` for portable comparison.
116 : */
117 : virtual void cancel() noexcept = 0;
118 :
119 : // Socket options
120 : virtual std::error_code set_no_delay(bool value) noexcept = 0;
121 : virtual bool no_delay(std::error_code& ec) const noexcept = 0;
122 :
123 : virtual std::error_code set_keep_alive(bool value) noexcept = 0;
124 : virtual bool keep_alive(std::error_code& ec) const noexcept = 0;
125 :
126 : virtual std::error_code set_receive_buffer_size(int size) noexcept = 0;
127 : virtual int receive_buffer_size(std::error_code& ec) const noexcept = 0;
128 :
129 : virtual std::error_code set_send_buffer_size(int size) noexcept = 0;
130 : virtual int send_buffer_size(std::error_code& ec) const noexcept = 0;
131 :
132 : virtual std::error_code
133 : set_linger(bool enabled, int timeout) noexcept = 0;
134 : virtual linger_options linger(std::error_code& ec) const noexcept = 0;
135 :
136 : /// Returns the cached local endpoint.
137 : virtual endpoint local_endpoint() const noexcept = 0;
138 :
139 : /// Returns the cached remote endpoint.
140 : virtual endpoint remote_endpoint() const noexcept = 0;
141 : };
142 :
143 : struct connect_awaitable
144 : {
145 : tcp_socket& s_;
146 : endpoint endpoint_;
147 : std::stop_token token_;
148 : mutable std::error_code ec_;
149 :
150 HIT 7907 : connect_awaitable(tcp_socket& s, endpoint ep) noexcept
151 7907 : : s_(s)
152 7907 : , endpoint_(ep)
153 : {
154 7907 : }
155 :
156 7907 : bool await_ready() const noexcept
157 : {
158 7907 : return token_.stop_requested();
159 : }
160 :
161 7907 : capy::io_result<> await_resume() const noexcept
162 : {
163 7907 : if (token_.stop_requested())
164 MIS 0 : return {make_error_code(std::errc::operation_canceled)};
165 HIT 7907 : return {ec_};
166 : }
167 :
168 7907 : auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
169 : -> std::coroutine_handle<>
170 : {
171 7907 : token_ = env->stop_token;
172 7907 : return s_.get().connect(h, env->executor, endpoint_, token_, &ec_);
173 : }
174 : };
175 :
176 : public:
177 : /** Destructor.
178 :
179 : Closes the socket if open, cancelling any pending operations.
180 : */
181 : ~tcp_socket() override;
182 :
183 : /** Construct a socket from an execution context.
184 :
185 : @param ctx The execution context that will own this socket.
186 : */
187 : explicit tcp_socket(capy::execution_context& ctx);
188 :
189 : /** Construct a socket from an executor.
190 :
191 : The socket is associated with the executor's context.
192 :
193 : @param ex The executor whose context will own the socket.
194 : */
195 : template<class Ex>
196 : requires(!std::same_as<std::remove_cvref_t<Ex>, tcp_socket>) &&
197 : capy::Executor<Ex>
198 : explicit tcp_socket(Ex const& ex) : tcp_socket(ex.context())
199 : {
200 : }
201 :
202 : /** Move constructor.
203 :
204 : Transfers ownership of the socket resources.
205 :
206 : @param other The socket to move from.
207 : */
208 188 : tcp_socket(tcp_socket&& other) noexcept : io_object(std::move(other)) {}
209 :
210 : /** Move assignment operator.
211 :
212 : Closes any existing socket and transfers ownership.
213 : @param other The socket to move from.
214 :
215 : @return Reference to this socket.
216 : */
217 10 : tcp_socket& operator=(tcp_socket&& other) noexcept
218 : {
219 10 : if (this != &other)
220 : {
221 10 : close();
222 10 : h_ = std::move(other.h_);
223 : }
224 10 : return *this;
225 : }
226 :
227 : tcp_socket(tcp_socket const&) = delete;
228 : tcp_socket& operator=(tcp_socket const&) = delete;
229 :
230 : /** Open the socket.
231 :
232 : Creates an IPv4 TCP socket and associates it with the platform
233 : reactor (IOCP on Windows). This must be called before initiating
234 : I/O operations.
235 :
236 : @throws std::system_error on failure.
237 : */
238 : void open();
239 :
240 : /** Close the socket.
241 :
242 : Releases socket resources. Any pending operations complete
243 : with `errc::operation_canceled`.
244 : */
245 : void close();
246 :
247 : /** Check if the socket is open.
248 :
249 : @return `true` if the socket is open and ready for operations.
250 : */
251 48363 : bool is_open() const noexcept
252 : {
253 : #if BOOST_COROSIO_HAS_IOCP
254 : return h_ && get().native_handle() != ~native_handle_type(0);
255 : #else
256 48363 : return h_ && get().native_handle() >= 0;
257 : #endif
258 : }
259 :
260 : /** Initiate an asynchronous connect operation.
261 :
262 : Connects the socket to the specified remote endpoint. The socket
263 : must be open before calling this function.
264 :
265 : The operation supports cancellation via `std::stop_token` through
266 : the affine awaitable protocol. If the associated stop token is
267 : triggered, the operation completes immediately with
268 : `errc::operation_canceled`.
269 :
270 : @param ep The remote endpoint to connect to.
271 :
272 : @return An awaitable that completes with `io_result<>`.
273 : Returns success (default error_code) on successful connection,
274 : or an error code on failure including:
275 : - connection_refused: No server listening at endpoint
276 : - timed_out: Connection attempt timed out
277 : - network_unreachable: No route to host
278 : - operation_canceled: Cancelled via stop_token or cancel().
279 : Check `ec == cond::canceled` for portable comparison.
280 :
281 : @throws std::logic_error if the socket is not open.
282 :
283 : @par Preconditions
284 : The socket must be open (`is_open() == true`).
285 :
286 : @par Example
287 : @code
288 : auto [ec] = co_await s.connect(endpoint);
289 : if (ec) { ... }
290 : @endcode
291 : */
292 7907 : auto connect(endpoint ep)
293 : {
294 7907 : if (!is_open())
295 MIS 0 : detail::throw_logic_error("connect: socket not open");
296 HIT 7907 : return connect_awaitable(*this, ep);
297 : }
298 :
299 : /** Cancel any pending asynchronous operations.
300 :
301 : All outstanding operations complete with `errc::operation_canceled`.
302 : Check `ec == cond::canceled` for portable comparison.
303 : */
304 : void cancel();
305 :
306 : /** Get the native socket handle.
307 :
308 : Returns the underlying platform-specific socket descriptor.
309 : On POSIX systems this is an `int` file descriptor.
310 : On Windows this is a `SOCKET` handle.
311 :
312 : @return The native socket handle, or -1/INVALID_SOCKET if not open.
313 :
314 : @par Preconditions
315 : None. May be called on closed sockets.
316 : */
317 : native_handle_type native_handle() const noexcept;
318 :
319 : /** Disable sends or receives on the socket.
320 :
321 : TCP connections are full-duplex: each direction (send and receive)
322 : operates independently. This function allows you to close one or
323 : both directions without destroying the socket.
324 :
325 : @li @ref shutdown_send sends a TCP FIN packet to the peer,
326 : signaling that you have no more data to send. You can still
327 : receive data until the peer also closes their send direction.
328 : This is the most common use case, typically called before
329 : close() to ensure graceful connection termination.
330 :
331 : @li @ref shutdown_receive disables reading on the socket. This
332 : does NOT send anything to the peer - they are not informed
333 : and may continue sending data. Subsequent reads will fail
334 : or return end-of-file. Incoming data may be discarded or
335 : buffered depending on the operating system.
336 :
337 : @li @ref shutdown_both combines both effects: sends a FIN and
338 : disables reading.
339 :
340 : When the peer shuts down their send direction (sends a FIN),
341 : subsequent read operations will complete with `capy::cond::eof`.
342 : Use the portable condition test rather than comparing error
343 : codes directly:
344 :
345 : @code
346 : auto [ec, n] = co_await sock.read_some(buffer);
347 : if (ec == capy::cond::eof)
348 : {
349 : // Peer closed their send direction
350 : }
351 : @endcode
352 :
353 : Any error from the underlying system call is silently discarded
354 : because it is unlikely to be helpful.
355 :
356 : @param what Determines what operations will no longer be allowed.
357 : */
358 : void shutdown(shutdown_type what);
359 :
360 : //
361 : // Socket Options
362 : //
363 :
364 : /** Enable or disable TCP_NODELAY (disable Nagle's algorithm).
365 :
366 : When enabled, segments are sent as soon as possible even if
367 : there is only a small amount of data. This reduces latency
368 : at the potential cost of increased network traffic.
369 :
370 : @param value `true` to disable Nagle's algorithm (enable no-delay).
371 :
372 : @throws std::logic_error if the socket is not open.
373 : @throws std::system_error on failure.
374 : */
375 : void set_no_delay(bool value);
376 :
377 : /** Get the current TCP_NODELAY setting.
378 :
379 : @return `true` if Nagle's algorithm is disabled.
380 :
381 : @throws std::logic_error if the socket is not open.
382 : @throws std::system_error on failure.
383 : */
384 : bool no_delay() const;
385 :
386 : /** Enable or disable SO_KEEPALIVE.
387 :
388 : When enabled, the socket will periodically send keepalive probes
389 : to detect if the peer is still reachable.
390 :
391 : @param value `true` to enable keepalive probes.
392 :
393 : @throws std::logic_error if the socket is not open.
394 : @throws std::system_error on failure.
395 : */
396 : void set_keep_alive(bool value);
397 :
398 : /** Get the current SO_KEEPALIVE setting.
399 :
400 : @return `true` if keepalive is enabled.
401 :
402 : @throws std::logic_error if the socket is not open.
403 : @throws std::system_error on failure.
404 : */
405 : bool keep_alive() const;
406 :
407 : /** Set the receive buffer size (SO_RCVBUF).
408 :
409 : @param size The desired receive buffer size in bytes.
410 :
411 : @throws std::logic_error if the socket is not open.
412 : @throws std::system_error on failure.
413 :
414 : @note The operating system may adjust the actual buffer size.
415 : */
416 : void set_receive_buffer_size(int size);
417 :
418 : /** Get the receive buffer size (SO_RCVBUF).
419 :
420 : @return The current receive buffer size in bytes.
421 :
422 : @throws std::logic_error if the socket is not open.
423 : @throws std::system_error on failure.
424 : */
425 : int receive_buffer_size() const;
426 :
427 : /** Set the send buffer size (SO_SNDBUF).
428 :
429 : @param size The desired send buffer size in bytes.
430 :
431 : @throws std::logic_error if the socket is not open.
432 : @throws std::system_error on failure.
433 :
434 : @note The operating system may adjust the actual buffer size.
435 : */
436 : void set_send_buffer_size(int size);
437 :
438 : /** Get the send buffer size (SO_SNDBUF).
439 :
440 : @return The current send buffer size in bytes.
441 :
442 : @throws std::logic_error if the socket is not open.
443 : @throws std::system_error on failure.
444 : */
445 : int send_buffer_size() const;
446 :
447 : /** Set the SO_LINGER option.
448 :
449 : Controls behavior when closing a socket with unsent data.
450 :
451 : @param enabled If `true`, close() will block until data is sent
452 : or the timeout expires. If `false`, close() returns immediately.
453 : @param timeout The linger timeout in seconds (only used if enabled).
454 :
455 : @throws std::logic_error if the socket is not open.
456 : @throws std::system_error on failure.
457 : */
458 : void set_linger(bool enabled, int timeout);
459 :
460 : /** Get the current SO_LINGER setting.
461 :
462 : @return The current linger options.
463 :
464 : @throws std::logic_error if the socket is not open.
465 : @throws std::system_error on failure.
466 : */
467 : linger_options linger() const;
468 :
469 : /** Get the local endpoint of the socket.
470 :
471 : Returns the local address and port to which the socket is bound.
472 : For a connected socket, this is the local side of the connection.
473 : The endpoint is cached when the connection is established.
474 :
475 : @return The local endpoint, or a default endpoint (0.0.0.0:0) if
476 : the socket is not connected.
477 :
478 : @par Thread Safety
479 : The cached endpoint value is set during connect/accept completion
480 : and cleared during close(). This function may be called concurrently
481 : with I/O operations, but must not be called concurrently with
482 : connect(), accept(), or close().
483 : */
484 : endpoint local_endpoint() const noexcept;
485 :
486 : /** Get the remote endpoint of the socket.
487 :
488 : Returns the remote address and port to which the socket is connected.
489 : The endpoint is cached when the connection is established.
490 :
491 : @return The remote endpoint, or a default endpoint (0.0.0.0:0) if
492 : the socket is not connected.
493 :
494 : @par Thread Safety
495 : The cached endpoint value is set during connect/accept completion
496 : and cleared during close(). This function may be called concurrently
497 : with I/O operations, but must not be called concurrently with
498 : connect(), accept(), or close().
499 : */
500 : endpoint remote_endpoint() const noexcept;
501 :
502 : protected:
503 10 : tcp_socket() noexcept = default;
504 :
505 : explicit tcp_socket(handle h) noexcept : io_object(std::move(h)) {}
506 :
507 : private:
508 : friend class tcp_acceptor;
509 :
510 56562 : inline implementation& get() const noexcept
511 : {
512 56562 : return *static_cast<implementation*>(h_.get());
513 : }
514 : };
515 :
516 : } // namespace boost::corosio
517 :
518 : #endif
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