Line data Source code
1 : //
2 : // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
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_TCP_SOCKET_HPP
11 : #define BOOST_COROSIO_TCP_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/io_stream.hpp>
17 : #include <boost/capy/io_result.hpp>
18 : #include <boost/corosio/io_buffer_param.hpp>
19 : #include <boost/corosio/endpoint.hpp>
20 : #include <boost/capy/ex/executor_ref.hpp>
21 : #include <boost/capy/ex/execution_context.hpp>
22 : #include <boost/capy/ex/io_env.hpp>
23 : #include <boost/capy/concept/executor.hpp>
24 :
25 : #include <system_error>
26 :
27 : #include <concepts>
28 : #include <coroutine>
29 : #include <cstddef>
30 : #include <memory>
31 : #include <stop_token>
32 : #include <type_traits>
33 :
34 : namespace boost::corosio {
35 :
36 : #if BOOST_COROSIO_HAS_IOCP
37 : using native_handle_type = std::uintptr_t; // SOCKET
38 : #else
39 : using native_handle_type = int;
40 : #endif
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 : @code
65 : io_context ioc;
66 : tcp_socket s(ioc);
67 : s.open();
68 :
69 : // Using structured bindings
70 : auto [ec] = co_await s.connect(
71 : endpoint(ipv4_address::loopback(), 8080));
72 : if (ec)
73 : co_return;
74 :
75 : char buf[1024];
76 : auto [read_ec, n] = co_await s.read_some(
77 : capy::mutable_buffer(buf, sizeof(buf)));
78 : @endcode
79 : */
80 : class BOOST_COROSIO_DECL tcp_socket : public io_stream
81 : {
82 : public:
83 : /** Different ways a socket may be shutdown. */
84 : enum shutdown_type
85 : {
86 : shutdown_receive,
87 : shutdown_send,
88 : shutdown_both
89 : };
90 :
91 : /** Options for SO_LINGER socket option. */
92 : struct linger_options
93 : {
94 : bool enabled = false;
95 : int timeout = 0; // seconds
96 : };
97 :
98 : struct socket_impl : io_stream_impl
99 : {
100 : virtual std::coroutine_handle<> connect(
101 : std::coroutine_handle<>,
102 : capy::executor_ref,
103 : endpoint,
104 : std::stop_token,
105 : std::error_code*) = 0;
106 :
107 : virtual std::error_code shutdown(shutdown_type) noexcept = 0;
108 :
109 : virtual native_handle_type native_handle() const noexcept = 0;
110 :
111 : /** Request cancellation of pending asynchronous operations.
112 :
113 : All outstanding operations complete with operation_canceled error.
114 : Check `ec == cond::canceled` for portable comparison.
115 : */
116 : virtual void cancel() noexcept = 0;
117 :
118 : // Socket options
119 : virtual std::error_code set_no_delay(bool value) noexcept = 0;
120 : virtual bool no_delay(std::error_code& ec) const noexcept = 0;
121 :
122 : virtual std::error_code set_keep_alive(bool value) noexcept = 0;
123 : virtual bool keep_alive(std::error_code& ec) const noexcept = 0;
124 :
125 : virtual std::error_code set_receive_buffer_size(int size) noexcept = 0;
126 : virtual int receive_buffer_size(std::error_code& ec) const noexcept = 0;
127 :
128 : virtual std::error_code set_send_buffer_size(int size) noexcept = 0;
129 : virtual int send_buffer_size(std::error_code& ec) const noexcept = 0;
130 :
131 : virtual std::error_code set_linger(bool enabled, int timeout) noexcept = 0;
132 : virtual linger_options linger(std::error_code& ec) const noexcept = 0;
133 :
134 : /// Returns the cached local endpoint.
135 : virtual endpoint local_endpoint() const noexcept = 0;
136 :
137 : /// Returns the cached remote endpoint.
138 : virtual endpoint remote_endpoint() const noexcept = 0;
139 : };
140 :
141 : struct connect_awaitable
142 : {
143 : tcp_socket& s_;
144 : endpoint endpoint_;
145 : std::stop_token token_;
146 : mutable std::error_code ec_;
147 :
148 8504 : connect_awaitable(tcp_socket& s, endpoint ep) noexcept
149 8504 : : s_(s)
150 8504 : , endpoint_(ep)
151 : {
152 8504 : }
153 :
154 8504 : bool await_ready() const noexcept
155 : {
156 8504 : return token_.stop_requested();
157 : }
158 :
159 8504 : capy::io_result<> await_resume() const noexcept
160 : {
161 8504 : if (token_.stop_requested())
162 0 : return {make_error_code(std::errc::operation_canceled)};
163 8504 : return {ec_};
164 : }
165 :
166 8504 : auto await_suspend(
167 : std::coroutine_handle<> h,
168 : capy::io_env const* env) -> std::coroutine_handle<>
169 : {
170 8504 : token_ = env->stop_token;
171 8504 : return s_.get().connect(h, env->executor, endpoint_, token_, &ec_);
172 : }
173 : };
174 :
175 : public:
176 : /** Destructor.
177 :
178 : Closes the socket if open, cancelling any pending operations.
179 : */
180 : ~tcp_socket();
181 :
182 : /** Construct a socket from an execution context.
183 :
184 : @param ctx The execution context that will own this socket.
185 : */
186 : explicit tcp_socket(capy::execution_context& ctx);
187 :
188 : /** Construct a socket from an executor.
189 :
190 : The socket is associated with the executor's context.
191 :
192 : @param ex The executor whose context will own the socket.
193 : */
194 : template<class Ex>
195 : requires (!std::same_as<std::remove_cvref_t<Ex>, tcp_socket>) &&
196 : capy::Executor<Ex>
197 : explicit tcp_socket(Ex const& ex)
198 : : 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 : */
208 180 : tcp_socket(tcp_socket&& other) noexcept
209 180 : : io_stream(other.context())
210 : {
211 180 : impl_ = other.impl_;
212 180 : other.impl_ = nullptr;
213 180 : }
214 :
215 : /** Move assignment operator.
216 :
217 : Closes any existing socket and transfers ownership.
218 : The source and destination must share the same execution context.
219 :
220 : @param other The socket to move from.
221 :
222 : @return Reference to this socket.
223 :
224 : @throws std::logic_error if the sockets have different execution contexts.
225 : */
226 8 : tcp_socket& operator=(tcp_socket&& other)
227 : {
228 8 : if (this != &other)
229 : {
230 8 : if (ctx_ != other.ctx_)
231 0 : detail::throw_logic_error(
232 : "cannot move socket across execution contexts");
233 8 : close();
234 8 : impl_ = other.impl_;
235 8 : other.impl_ = nullptr;
236 : }
237 8 : return *this;
238 : }
239 :
240 : tcp_socket(tcp_socket const&) = delete;
241 : tcp_socket& operator=(tcp_socket const&) = delete;
242 :
243 : /** Open the socket.
244 :
245 : Creates an IPv4 TCP socket and associates it with the platform
246 : reactor (IOCP on Windows). This must be called before initiating
247 : I/O operations.
248 :
249 : @throws std::system_error on failure.
250 : */
251 : void open();
252 :
253 : /** Close the socket.
254 :
255 : Releases socket resources. Any pending operations complete
256 : with `errc::operation_canceled`.
257 : */
258 : void close();
259 :
260 : /** Check if the socket is open.
261 :
262 : @return `true` if the socket is open and ready for operations.
263 : */
264 28 : bool is_open() const noexcept
265 : {
266 28 : return impl_ != nullptr;
267 : }
268 :
269 : /** Initiate an asynchronous connect operation.
270 :
271 : Connects the socket to the specified remote endpoint. The socket
272 : must be open before calling this function.
273 :
274 : The operation supports cancellation via `std::stop_token` through
275 : the affine awaitable protocol. If the associated stop token is
276 : triggered, the operation completes immediately with
277 : `errc::operation_canceled`.
278 :
279 : @param ep The remote endpoint to connect to.
280 :
281 : @return An awaitable that completes with `io_result<>`.
282 : Returns success (default error_code) on successful connection,
283 : or an error code on failure including:
284 : - connection_refused: No server listening at endpoint
285 : - timed_out: Connection attempt timed out
286 : - network_unreachable: No route to host
287 : - operation_canceled: Cancelled via stop_token or cancel().
288 : Check `ec == cond::canceled` for portable comparison.
289 :
290 : @throws std::logic_error if the socket is not open.
291 :
292 : @par Preconditions
293 : The socket must be open (`is_open() == true`).
294 :
295 : @par Example
296 : @code
297 : auto [ec] = co_await s.connect(endpoint);
298 : if (ec) { ... }
299 : @endcode
300 : */
301 8504 : auto connect(endpoint ep)
302 : {
303 8504 : if (!impl_)
304 0 : detail::throw_logic_error("connect: socket not open");
305 8504 : return connect_awaitable(*this, ep);
306 : }
307 :
308 : /** Cancel any pending asynchronous operations.
309 :
310 : All outstanding operations complete with `errc::operation_canceled`.
311 : Check `ec == cond::canceled` for portable comparison.
312 : */
313 : void cancel();
314 :
315 : /** Get the native socket handle.
316 :
317 : Returns the underlying platform-specific socket descriptor.
318 : On POSIX systems this is an `int` file descriptor.
319 : On Windows this is a `SOCKET` handle.
320 :
321 : @return The native socket handle, or -1/INVALID_SOCKET if not open.
322 :
323 : @par Preconditions
324 : None. May be called on closed sockets.
325 : */
326 : native_handle_type native_handle() const noexcept;
327 :
328 : /** Disable sends or receives on the socket.
329 :
330 : TCP connections are full-duplex: each direction (send and receive)
331 : operates independently. This function allows you to close one or
332 : both directions without destroying the socket.
333 :
334 : @li @ref shutdown_send sends a TCP FIN packet to the peer,
335 : signaling that you have no more data to send. You can still
336 : receive data until the peer also closes their send direction.
337 : This is the most common use case, typically called before
338 : close() to ensure graceful connection termination.
339 :
340 : @li @ref shutdown_receive disables reading on the socket. This
341 : does NOT send anything to the peer - they are not informed
342 : and may continue sending data. Subsequent reads will fail
343 : or return end-of-file. Incoming data may be discarded or
344 : buffered depending on the operating system.
345 :
346 : @li @ref shutdown_both combines both effects: sends a FIN and
347 : disables reading.
348 :
349 : When the peer shuts down their send direction (sends a FIN),
350 : subsequent read operations will complete with `capy::cond::eof`.
351 : Use the portable condition test rather than comparing error
352 : codes directly:
353 :
354 : @code
355 : auto [ec, n] = co_await sock.read_some(buffer);
356 : if (ec == capy::cond::eof)
357 : {
358 : // Peer closed their send direction
359 : }
360 : @endcode
361 :
362 : Any error from the underlying system call is silently discarded
363 : because it is unlikely to be helpful.
364 :
365 : @param what Determines what operations will no longer be allowed.
366 : */
367 : void shutdown(shutdown_type what);
368 :
369 : //--------------------------------------------------------------------------
370 : //
371 : // Socket Options
372 : //
373 : //--------------------------------------------------------------------------
374 :
375 : /** Enable or disable TCP_NODELAY (disable Nagle's algorithm).
376 :
377 : When enabled, segments are sent as soon as possible even if
378 : there is only a small amount of data. This reduces latency
379 : at the potential cost of increased network traffic.
380 :
381 : @param value `true` to disable Nagle's algorithm (enable no-delay).
382 :
383 : @throws std::logic_error if the socket is not open.
384 : @throws std::system_error on failure.
385 : */
386 : void set_no_delay(bool value);
387 :
388 : /** Get the current TCP_NODELAY setting.
389 :
390 : @return `true` if Nagle's algorithm is disabled.
391 :
392 : @throws std::logic_error if the socket is not open.
393 : @throws std::system_error on failure.
394 : */
395 : bool no_delay() const;
396 :
397 : /** Enable or disable SO_KEEPALIVE.
398 :
399 : When enabled, the socket will periodically send keepalive probes
400 : to detect if the peer is still reachable.
401 :
402 : @param value `true` to enable keepalive probes.
403 :
404 : @throws std::logic_error if the socket is not open.
405 : @throws std::system_error on failure.
406 : */
407 : void set_keep_alive(bool value);
408 :
409 : /** Get the current SO_KEEPALIVE setting.
410 :
411 : @return `true` if keepalive is enabled.
412 :
413 : @throws std::logic_error if the socket is not open.
414 : @throws std::system_error on failure.
415 : */
416 : bool keep_alive() const;
417 :
418 : /** Set the receive buffer size (SO_RCVBUF).
419 :
420 : @param size The desired 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 : @note The operating system may adjust the actual buffer size.
426 : */
427 : void set_receive_buffer_size(int size);
428 :
429 : /** Get the receive buffer size (SO_RCVBUF).
430 :
431 : @return The current receive buffer size in bytes.
432 :
433 : @throws std::logic_error if the socket is not open.
434 : @throws std::system_error on failure.
435 : */
436 : int receive_buffer_size() const;
437 :
438 : /** Set the send buffer size (SO_SNDBUF).
439 :
440 : @param size The desired 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 : @note The operating system may adjust the actual buffer size.
446 : */
447 : void set_send_buffer_size(int size);
448 :
449 : /** Get the send buffer size (SO_SNDBUF).
450 :
451 : @return The current send buffer size in bytes.
452 :
453 : @throws std::logic_error if the socket is not open.
454 : @throws std::system_error on failure.
455 : */
456 : int send_buffer_size() const;
457 :
458 : /** Set the SO_LINGER option.
459 :
460 : Controls behavior when closing a socket with unsent data.
461 :
462 : @param enabled If `true`, close() will block until data is sent
463 : or the timeout expires. If `false`, close() returns immediately.
464 : @param timeout The linger timeout in seconds (only used if enabled).
465 :
466 : @throws std::logic_error if the socket is not open.
467 : @throws std::system_error on failure.
468 : */
469 : void set_linger(bool enabled, int timeout);
470 :
471 : /** Get the current SO_LINGER setting.
472 :
473 : @return The current linger options.
474 :
475 : @throws std::logic_error if the socket is not open.
476 : @throws std::system_error on failure.
477 : */
478 : linger_options linger() const;
479 :
480 : /** Get the local endpoint of the socket.
481 :
482 : Returns the local address and port to which the socket is bound.
483 : For a connected socket, this is the local side of the connection.
484 : The endpoint is cached when the connection is established.
485 :
486 : @return The local endpoint, or a default endpoint (0.0.0.0:0) if
487 : the socket is not connected.
488 :
489 : @par Thread Safety
490 : The cached endpoint value is set during connect/accept completion
491 : and cleared during close(). This function may be called concurrently
492 : with I/O operations, but must not be called concurrently with
493 : connect(), accept(), or close().
494 : */
495 : endpoint local_endpoint() const noexcept;
496 :
497 : /** Get the remote endpoint of the socket.
498 :
499 : Returns the remote address and port to which the socket is connected.
500 : The endpoint is cached when the connection is established.
501 :
502 : @return The remote endpoint, or a default endpoint (0.0.0.0:0) if
503 : the socket is not connected.
504 :
505 : @par Thread Safety
506 : The cached endpoint value is set during connect/accept completion
507 : and cleared during close(). This function may be called concurrently
508 : with I/O operations, but must not be called concurrently with
509 : connect(), accept(), or close().
510 : */
511 : endpoint remote_endpoint() const noexcept;
512 :
513 : private:
514 : friend class tcp_acceptor;
515 :
516 8917 : inline socket_impl& get() const noexcept
517 : {
518 8917 : return *static_cast<socket_impl*>(impl_);
519 : }
520 : };
521 :
522 : } // namespace boost::corosio
523 :
524 : #endif
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