TLA 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 implementation : io_stream::implementation
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
132 : set_linger(bool enabled, int timeout) noexcept = 0;
133 : virtual linger_options linger(std::error_code& ec) const noexcept = 0;
134 :
135 : /// Returns the cached local endpoint.
136 : virtual endpoint local_endpoint() const noexcept = 0;
137 :
138 : /// Returns the cached remote endpoint.
139 : virtual endpoint remote_endpoint() const noexcept = 0;
140 : };
141 :
142 : struct connect_awaitable
143 : {
144 : tcp_socket& s_;
145 : endpoint endpoint_;
146 : std::stop_token token_;
147 : mutable std::error_code ec_;
148 :
149 HIT 8378 : connect_awaitable(tcp_socket& s, endpoint ep) noexcept
150 8378 : : s_(s)
151 8378 : , endpoint_(ep)
152 : {
153 8378 : }
154 :
155 8378 : bool await_ready() const noexcept
156 : {
157 8378 : return token_.stop_requested();
158 : }
159 :
160 8378 : capy::io_result<> await_resume() const noexcept
161 : {
162 8378 : if (token_.stop_requested())
163 MIS 0 : return {make_error_code(std::errc::operation_canceled)};
164 HIT 8378 : return {ec_};
165 : }
166 :
167 8378 : auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
168 : -> std::coroutine_handle<>
169 : {
170 8378 : token_ = env->stop_token;
171 8378 : 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() override;
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) : tcp_socket(ex.context())
198 : {
199 : }
200 :
201 : /** Move constructor.
202 :
203 : Transfers ownership of the socket resources.
204 :
205 : @param other The socket to move from.
206 : */
207 180 : tcp_socket(tcp_socket&& other) noexcept : io_stream(std::move(other)) {}
208 :
209 : /** Move assignment operator.
210 :
211 : Closes any existing socket and transfers ownership.
212 : @param other The socket to move from.
213 :
214 : @return Reference to this socket.
215 : */
216 8 : tcp_socket& operator=(tcp_socket&& other) noexcept
217 : {
218 8 : if (this != &other)
219 : {
220 8 : close();
221 8 : h_ = std::move(other.h_);
222 : }
223 8 : return *this;
224 : }
225 :
226 : tcp_socket(tcp_socket const&) = delete;
227 : tcp_socket& operator=(tcp_socket const&) = delete;
228 :
229 : /** Open the socket.
230 :
231 : Creates an IPv4 TCP socket and associates it with the platform
232 : reactor (IOCP on Windows). This must be called before initiating
233 : I/O operations.
234 :
235 : @throws std::system_error on failure.
236 : */
237 : void open();
238 :
239 : /** Close the socket.
240 :
241 : Releases socket resources. Any pending operations complete
242 : with `errc::operation_canceled`.
243 : */
244 : void close();
245 :
246 : /** Check if the socket is open.
247 :
248 : @return `true` if the socket is open and ready for operations.
249 : */
250 51139 : bool is_open() const noexcept
251 : {
252 : #if BOOST_COROSIO_HAS_IOCP
253 : return h_ && get().native_handle() != ~native_handle_type(0);
254 : #else
255 51139 : return h_ && get().native_handle() >= 0;
256 : #endif
257 : }
258 :
259 : /** Initiate an asynchronous connect operation.
260 :
261 : Connects the socket to the specified remote endpoint. The socket
262 : must be open before calling this function.
263 :
264 : The operation supports cancellation via `std::stop_token` through
265 : the affine awaitable protocol. If the associated stop token is
266 : triggered, the operation completes immediately with
267 : `errc::operation_canceled`.
268 :
269 : @param ep The remote endpoint to connect to.
270 :
271 : @return An awaitable that completes with `io_result<>`.
272 : Returns success (default error_code) on successful connection,
273 : or an error code on failure including:
274 : - connection_refused: No server listening at endpoint
275 : - timed_out: Connection attempt timed out
276 : - network_unreachable: No route to host
277 : - operation_canceled: Cancelled via stop_token or cancel().
278 : Check `ec == cond::canceled` for portable comparison.
279 :
280 : @throws std::logic_error if the socket is not open.
281 :
282 : @par Preconditions
283 : The socket must be open (`is_open() == true`).
284 :
285 : @par Example
286 : @code
287 : auto [ec] = co_await s.connect(endpoint);
288 : if (ec) { ... }
289 : @endcode
290 : */
291 8378 : auto connect(endpoint ep)
292 : {
293 8378 : if (!is_open())
294 MIS 0 : detail::throw_logic_error("connect: socket not open");
295 HIT 8378 : return connect_awaitable(*this, ep);
296 : }
297 :
298 : /** Cancel any pending asynchronous operations.
299 :
300 : All outstanding operations complete with `errc::operation_canceled`.
301 : Check `ec == cond::canceled` for portable comparison.
302 : */
303 : void cancel();
304 :
305 : /** Get the native socket handle.
306 :
307 : Returns the underlying platform-specific socket descriptor.
308 : On POSIX systems this is an `int` file descriptor.
309 : On Windows this is a `SOCKET` handle.
310 :
311 : @return The native socket handle, or -1/INVALID_SOCKET if not open.
312 :
313 : @par Preconditions
314 : None. May be called on closed sockets.
315 : */
316 : native_handle_type native_handle() const noexcept;
317 :
318 : /** Disable sends or receives on the socket.
319 :
320 : TCP connections are full-duplex: each direction (send and receive)
321 : operates independently. This function allows you to close one or
322 : both directions without destroying the socket.
323 :
324 : @li @ref shutdown_send sends a TCP FIN packet to the peer,
325 : signaling that you have no more data to send. You can still
326 : receive data until the peer also closes their send direction.
327 : This is the most common use case, typically called before
328 : close() to ensure graceful connection termination.
329 :
330 : @li @ref shutdown_receive disables reading on the socket. This
331 : does NOT send anything to the peer - they are not informed
332 : and may continue sending data. Subsequent reads will fail
333 : or return end-of-file. Incoming data may be discarded or
334 : buffered depending on the operating system.
335 :
336 : @li @ref shutdown_both combines both effects: sends a FIN and
337 : disables reading.
338 :
339 : When the peer shuts down their send direction (sends a FIN),
340 : subsequent read operations will complete with `capy::cond::eof`.
341 : Use the portable condition test rather than comparing error
342 : codes directly:
343 :
344 : @code
345 : auto [ec, n] = co_await sock.read_some(buffer);
346 : if (ec == capy::cond::eof)
347 : {
348 : // Peer closed their send direction
349 : }
350 : @endcode
351 :
352 : Any error from the underlying system call is silently discarded
353 : because it is unlikely to be helpful.
354 :
355 : @param what Determines what operations will no longer be allowed.
356 : */
357 : void shutdown(shutdown_type what);
358 :
359 : //
360 : // Socket Options
361 : //
362 :
363 : /** Enable or disable TCP_NODELAY (disable Nagle's algorithm).
364 :
365 : When enabled, segments are sent as soon as possible even if
366 : there is only a small amount of data. This reduces latency
367 : at the potential cost of increased network traffic.
368 :
369 : @param value `true` to disable Nagle's algorithm (enable no-delay).
370 :
371 : @throws std::logic_error if the socket is not open.
372 : @throws std::system_error on failure.
373 : */
374 : void set_no_delay(bool value);
375 :
376 : /** Get the current TCP_NODELAY setting.
377 :
378 : @return `true` if Nagle's algorithm is disabled.
379 :
380 : @throws std::logic_error if the socket is not open.
381 : @throws std::system_error on failure.
382 : */
383 : bool no_delay() const;
384 :
385 : /** Enable or disable SO_KEEPALIVE.
386 :
387 : When enabled, the socket will periodically send keepalive probes
388 : to detect if the peer is still reachable.
389 :
390 : @param value `true` to enable keepalive probes.
391 :
392 : @throws std::logic_error if the socket is not open.
393 : @throws std::system_error on failure.
394 : */
395 : void set_keep_alive(bool value);
396 :
397 : /** Get the current SO_KEEPALIVE setting.
398 :
399 : @return `true` if keepalive is enabled.
400 :
401 : @throws std::logic_error if the socket is not open.
402 : @throws std::system_error on failure.
403 : */
404 : bool keep_alive() const;
405 :
406 : /** Set the receive buffer size (SO_RCVBUF).
407 :
408 : @param size The desired receive buffer size in bytes.
409 :
410 : @throws std::logic_error if the socket is not open.
411 : @throws std::system_error on failure.
412 :
413 : @note The operating system may adjust the actual buffer size.
414 : */
415 : void set_receive_buffer_size(int size);
416 :
417 : /** Get the receive buffer size (SO_RCVBUF).
418 :
419 : @return The current receive buffer size in bytes.
420 :
421 : @throws std::logic_error if the socket is not open.
422 : @throws std::system_error on failure.
423 : */
424 : int receive_buffer_size() const;
425 :
426 : /** Set the send buffer size (SO_SNDBUF).
427 :
428 : @param size The desired send buffer size in bytes.
429 :
430 : @throws std::logic_error if the socket is not open.
431 : @throws std::system_error on failure.
432 :
433 : @note The operating system may adjust the actual buffer size.
434 : */
435 : void set_send_buffer_size(int size);
436 :
437 : /** Get the send buffer size (SO_SNDBUF).
438 :
439 : @return The current send buffer size in bytes.
440 :
441 : @throws std::logic_error if the socket is not open.
442 : @throws std::system_error on failure.
443 : */
444 : int send_buffer_size() const;
445 :
446 : /** Set the SO_LINGER option.
447 :
448 : Controls behavior when closing a socket with unsent data.
449 :
450 : @param enabled If `true`, close() will block until data is sent
451 : or the timeout expires. If `false`, close() returns immediately.
452 : @param timeout The linger timeout in seconds (only used if enabled).
453 :
454 : @throws std::logic_error if the socket is not open.
455 : @throws std::system_error on failure.
456 : */
457 : void set_linger(bool enabled, int timeout);
458 :
459 : /** Get the current SO_LINGER setting.
460 :
461 : @return The current linger options.
462 :
463 : @throws std::logic_error if the socket is not open.
464 : @throws std::system_error on failure.
465 : */
466 : linger_options linger() const;
467 :
468 : /** Get the local endpoint of the socket.
469 :
470 : Returns the local address and port to which the socket is bound.
471 : For a connected socket, this is the local side of the connection.
472 : The endpoint is cached when the connection is established.
473 :
474 : @return The local endpoint, or a default endpoint (0.0.0.0:0) if
475 : the socket is not connected.
476 :
477 : @par Thread Safety
478 : The cached endpoint value is set during connect/accept completion
479 : and cleared during close(). This function may be called concurrently
480 : with I/O operations, but must not be called concurrently with
481 : connect(), accept(), or close().
482 : */
483 : endpoint local_endpoint() const noexcept;
484 :
485 : /** Get the remote endpoint of the socket.
486 :
487 : Returns the remote address and port to which the socket is connected.
488 : The endpoint is cached when the connection is established.
489 :
490 : @return The remote endpoint, or a default endpoint (0.0.0.0:0) if
491 : the socket is not connected.
492 :
493 : @par Thread Safety
494 : The cached endpoint value is set during connect/accept completion
495 : and cleared during close(). This function may be called concurrently
496 : with I/O operations, but must not be called concurrently with
497 : connect(), accept(), or close().
498 : */
499 : endpoint remote_endpoint() const noexcept;
500 :
501 : private:
502 : friend class tcp_acceptor;
503 :
504 59817 : inline implementation& get() const noexcept
505 : {
506 59817 : return *static_cast<implementation*>(h_.get());
507 : }
508 : };
509 :
510 : } // namespace boost::corosio
511 :
512 : #endif
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