include/boost/corosio/native/detail/posix/posix_resolver_service.hpp

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posix_resolver_service.hpp

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1		//
2		// Copyright (c) 2026 Steve Gerbino
3		// Copyright (c) 2026 Michael Vandeberg
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_NATIVE_DETAIL_POSIX_POSIX_RESOLVER_SERVICE_HPP
12		#define BOOST_COROSIO_NATIVE_DETAIL_POSIX_POSIX_RESOLVER_SERVICE_HPP
13
14		#include <boost/corosio/detail/platform.hpp>
15
16		#if BOOST_COROSIO_POSIX
17
18		#include <boost/corosio/native/detail/posix/posix_resolver.hpp>
19		#include <boost/corosio/native/detail/reactor/reactor_scheduler.hpp>
20		#include <boost/corosio/detail/thread_pool.hpp>
21
22		#include <unordered_map>
23
24		namespace boost::corosio::detail {
25
26		/** Resolver service for POSIX backends.
27
28		Owns all posix_resolver instances. Thread lifecycle is managed
29		by the thread_pool service.
30		*/
31		class BOOST_COROSIO_DECL posix_resolver_service final
32		: public capy::execution_context::service
33		, public io_object::io_service
34		{
35		public:
36		using key_type = posix_resolver_service;
37
38	1876x	posix_resolver_service(capy::execution_context& ctx, scheduler& sched)
39	3752x	: sched_(&sched)
40	1876x	, pool_(ctx.use_service<thread_pool>())
41		{
42	1876x	}
43
44	3752x	~posix_resolver_service() override = default;
45
46		posix_resolver_service(posix_resolver_service const&) = delete;
47		posix_resolver_service& operator=(posix_resolver_service const&) = delete;
48
49		io_object::implementation* construct() override;
50
51	46x	void destroy(io_object::implementation* p) override
52		{
53	46x	auto& impl = static_cast<posix_resolver&>(*p);
54	46x	impl.cancel();
55	46x	destroy_impl(impl);
56	46x	}
57
58		void shutdown() override;
59		void destroy_impl(posix_resolver& impl);
60
61		void post(scheduler_op* op);
62		void work_started() noexcept;
63		void work_finished() noexcept;
64
65		/** Return the resolver thread pool. */
66	35x	thread_pool& pool() noexcept
67		{
68	35x	return pool_;
69		}
70
71		/// True when the resolver thread pool is unavailable: the `unsafe` tier,
72		/// whose lockless scheduler cannot accept the pool's cross-thread
73		/// completions.
74	37x	bool resolver_unavailable() const noexcept
75		{
76	37x	return sched_->scheduler_locking_disabled();
77		}
78
79		private:
80		scheduler* sched_;
81		thread_pool& pool_;
82		std::mutex mutex_;
83		intrusive_list<posix_resolver> resolver_list_;
84		std::unordered_map<posix_resolver*, std::shared_ptr<posix_resolver>>
85		resolver_ptrs_;
86		};
87
88		/** Get or create the resolver service for the given context.
89
90		This function is called by the concrete scheduler during initialization
91		to create the resolver service with a reference to itself.
92
93		@param ctx Reference to the owning execution_context.
94		@param sched Reference to the scheduler for posting completions.
95		@return Reference to the resolver service.
96		*/
97		posix_resolver_service&
98		get_resolver_service(capy::execution_context& ctx, scheduler& sched);
99
100		// ---------------------------------------------------------------------------
101		// Inline implementation
102		// ---------------------------------------------------------------------------
103
104		// posix_resolver_detail helpers
105
106		inline int
107	23x	posix_resolver_detail::flags_to_hints(resolve_flags flags)
108		{
109	23x	int hints = 0;
110
111	23x	if ((flags & resolve_flags::passive) != resolve_flags::none)
112	1x	hints \|= AI_PASSIVE;
113	23x	if ((flags & resolve_flags::numeric_host) != resolve_flags::none)
114	12x	hints \|= AI_NUMERICHOST;
115	23x	if ((flags & resolve_flags::numeric_service) != resolve_flags::none)
116	9x	hints \|= AI_NUMERICSERV;
117	23x	if ((flags & resolve_flags::address_configured) != resolve_flags::none)
118	1x	hints \|= AI_ADDRCONFIG;
119	23x	if ((flags & resolve_flags::v4_mapped) != resolve_flags::none)
120	1x	hints \|= AI_V4MAPPED;
121	23x	if ((flags & resolve_flags::all_matching) != resolve_flags::none)
122	1x	hints \|= AI_ALL;
123
124	23x	return hints;
125		}
126
127		inline int
128	12x	posix_resolver_detail::flags_to_ni_flags(reverse_flags flags)
129		{
130	12x	int ni_flags = 0;
131
132	12x	if ((flags & reverse_flags::numeric_host) != reverse_flags::none)
133	6x	ni_flags \|= NI_NUMERICHOST;
134	12x	if ((flags & reverse_flags::numeric_service) != reverse_flags::none)
135	6x	ni_flags \|= NI_NUMERICSERV;
136	12x	if ((flags & reverse_flags::name_required) != reverse_flags::none)
137	1x	ni_flags \|= NI_NAMEREQD;
138	12x	if ((flags & reverse_flags::datagram_service) != reverse_flags::none)
139	1x	ni_flags \|= NI_DGRAM;
140
141	12x	return ni_flags;
142		}
143
144		inline resolver_results
145	18x	posix_resolver_detail::convert_results(
146		struct addrinfo* ai, std::string_view host, std::string_view service)
147		{
148	18x	std::vector<resolver_entry> entries;
149	18x	entries.reserve(4); // Most lookups return 1-4 addresses
150
151	44x	for (auto* p = ai; p != nullptr; p = p->ai_next)
152		{
153	26x	if (p->ai_family == AF_INET)
154		{
155	16x	auto* addr = reinterpret_cast<sockaddr_in*>(p->ai_addr);
156	16x	auto ep = from_sockaddr_in(*addr);
157	16x	entries.emplace_back(ep, host, service);
158		}
159	10x	else if (p->ai_family == AF_INET6)
160		{
161	10x	auto* addr = reinterpret_cast<sockaddr_in6*>(p->ai_addr);
162	10x	auto ep = from_sockaddr_in6(*addr);
163	10x	entries.emplace_back(ep, host, service);
164		}
165		}
166
167	18x	return entries;
168	✗	}
169
170		inline std::error_code
171	14x	posix_resolver_detail::make_gai_error(int gai_err)
172		{
173		// Map GAI errors to appropriate generic error codes
174	14x	switch (gai_err)
175		{
176	1x	case EAI_AGAIN:
177		// Temporary failure - try again later
178	1x	return std::error_code(
179		static_cast<int>(std::errc::resource_unavailable_try_again),
180	1x	std::generic_category());
181
182	1x	case EAI_BADFLAGS:
183		// Invalid flags
184	1x	return std::error_code(
185		static_cast<int>(std::errc::invalid_argument),
186	1x	std::generic_category());
187
188	1x	case EAI_FAIL:
189		// Non-recoverable failure
190	1x	return std::error_code(
191	1x	static_cast<int>(std::errc::io_error), std::generic_category());
192
193	1x	case EAI_FAMILY:
194		// Address family not supported
195	1x	return std::error_code(
196		static_cast<int>(std::errc::address_family_not_supported),
197	1x	std::generic_category());
198
199	1x	case EAI_MEMORY:
200		// Memory allocation failure
201	1x	return std::error_code(
202		static_cast<int>(std::errc::not_enough_memory),
203	1x	std::generic_category());
204
205	5x	case EAI_NONAME:
206		// Host or service not found
207	5x	return std::error_code(
208		static_cast<int>(std::errc::no_such_device_or_address),
209	5x	std::generic_category());
210
211	1x	case EAI_SERVICE:
212		// Service not supported for socket type
213	1x	return std::error_code(
214		static_cast<int>(std::errc::invalid_argument),
215	1x	std::generic_category());
216
217	1x	case EAI_SOCKTYPE:
218		// Socket type not supported
219	1x	return std::error_code(
220		static_cast<int>(std::errc::not_supported),
221	1x	std::generic_category());
222
223	1x	case EAI_SYSTEM:
224		// System error - use errno
225	1x	return std::error_code(errno, std::generic_category());
226
227	1x	default:
228		// Unknown error
229	1x	return std::error_code(
230	1x	static_cast<int>(std::errc::io_error), std::generic_category());
231		}
232		}
233
234		// posix_resolver
235
236	46x	inline posix_resolver::posix_resolver(posix_resolver_service& svc) noexcept
237	46x	: svc_(svc)
238		{
239	46x	}
240
241		// posix_resolver::resolve_op implementation
242
243		inline void
244	23x	posix_resolver::resolve_op::reset() noexcept
245		{
246	23x	host.clear();
247	23x	service.clear();
248	23x	flags = resolve_flags::none;
249	23x	stored_results = resolver_results{};
250	23x	gai_error = 0;
251	23x	cancelled.store(false, std::memory_order_relaxed);
252	23x	stop_cb.reset();
253	23x	ec_out = nullptr;
254	23x	out = nullptr;
255	23x	}
256
257		inline void
258	23x	posix_resolver::resolve_op::operator()()
259		{
260	23x	stop_cb.reset(); // Disconnect stop callback
261
262	23x	bool const was_cancelled = cancelled.load(std::memory_order_acquire);
263
264	23x	if (ec_out)
265		{
266	23x	if (was_cancelled)
267	1x	*ec_out = capy::error::canceled;
268	22x	else if (gai_error != 0)
269	4x	*ec_out = posix_resolver_detail::make_gai_error(gai_error);
270		else
271	18x	*ec_out = {}; // Clear on success
272		}
273
274	23x	if (out && !was_cancelled && gai_error == 0)
275	18x	*out = std::move(stored_results);
276
277	23x	impl->svc_.work_finished();
278	23x	cont.h = h;
279	23x	dispatch_coro(ex, cont).resume();
280	23x	}
281
282		inline void
283	✗	posix_resolver::resolve_op::destroy()
284		{
285	✗	stop_cb.reset();
286	✗	}
287
288		inline void
289	51x	posix_resolver::resolve_op::request_cancel() noexcept
290		{
291	51x	cancelled.store(true, std::memory_order_release);
292	51x	}
293
294		inline void
295	23x	posix_resolver::resolve_op::start(std::stop_token const& token)
296		{
297	23x	cancelled.store(false, std::memory_order_release);
298	23x	stop_cb.reset();
299
300	23x	if (token.stop_possible())
301	1x	stop_cb.emplace(token, canceller{this});
302	23x	}
303
304		// posix_resolver::reverse_resolve_op implementation
305
306		inline void
307	12x	posix_resolver::reverse_resolve_op::reset() noexcept
308		{
309	12x	ep = endpoint{};
310	12x	flags = reverse_flags::none;
311	12x	stored_host.clear();
312	12x	stored_service.clear();
313	12x	gai_error = 0;
314	12x	cancelled.store(false, std::memory_order_relaxed);
315	12x	stop_cb.reset();
316	12x	ec_out = nullptr;
317	12x	result_out = nullptr;
318	12x	}
319
320		inline void
321	12x	posix_resolver::reverse_resolve_op::operator()()
322		{
323	12x	stop_cb.reset(); // Disconnect stop callback
324
325	12x	bool const was_cancelled = cancelled.load(std::memory_order_acquire);
326
327	12x	if (ec_out)
328		{
329	12x	if (was_cancelled)
330	1x	*ec_out = capy::error::canceled;
331	11x	else if (gai_error != 0)
332	1x	*ec_out = posix_resolver_detail::make_gai_error(gai_error);
333		else
334	10x	*ec_out = {}; // Clear on success
335		}
336
337	12x	if (result_out && !was_cancelled && gai_error == 0)
338		{
339	30x	*result_out = reverse_resolver_result(
340	30x	ep, std::move(stored_host), std::move(stored_service));
341		}
342
343	12x	impl->svc_.work_finished();
344	12x	cont.h = h;
345	12x	dispatch_coro(ex, cont).resume();
346	12x	}
347
348		inline void
349	✗	posix_resolver::reverse_resolve_op::destroy()
350		{
351	✗	stop_cb.reset();
352	✗	}
353
354		inline void
355	51x	posix_resolver::reverse_resolve_op::request_cancel() noexcept
356		{
357	51x	cancelled.store(true, std::memory_order_release);
358	51x	}
359
360		inline void
361	12x	posix_resolver::reverse_resolve_op::start(std::stop_token const& token)
362		{
363	12x	cancelled.store(false, std::memory_order_release);
364	12x	stop_cb.reset();
365
366	12x	if (token.stop_possible())
367	1x	stop_cb.emplace(token, canceller{this});
368	12x	}
369
370		// posix_resolver implementation
371
372		inline std::coroutine_handle<>
373	24x	posix_resolver::resolve(
374		std::coroutine_handle<> h,
375		capy::executor_ref ex,
376		std::string_view host,
377		std::string_view service,
378		resolve_flags flags,
379		std::stop_token token,
380		std::error_code* ec,
381		resolver_results* out)
382		{
383	24x	if (svc_.resolver_unavailable())
384		{
385	1x	*ec = std::make_error_code(std::errc::operation_not_supported);
386	1x	op_.cont.h = h;
387	1x	return dispatch_coro(ex, op_.cont);
388		}
389
390	23x	auto& op = op_;
391	23x	op.reset();
392	23x	op.h = h;
393	23x	op.ex = ex;
394	23x	op.impl = this;
395	23x	op.ec_out = ec;
396	23x	op.out = out;
397	23x	op.host = host;
398	23x	op.service = service;
399	23x	op.flags = flags;
400	23x	op.start(token);
401
402		// Keep io_context alive while resolution is pending
403	23x	op.ex.on_work_started();
404
405		// Prevent impl destruction while work is in flight
406	23x	resolve_pool_op_.resolver_ = this;
407	23x	resolve_pool_op_.ref_ = this->shared_from_this();
408	23x	resolve_pool_op_.func_ = &posix_resolver::do_resolve_work;
409	23x	if (!svc_.pool().post(&resolve_pool_op_))
410		{
411		// Pool shut down — complete with cancellation
412	✗	resolve_pool_op_.ref_.reset();
413	✗	op.cancelled.store(true, std::memory_order_release);
414	✗	svc_.post(&op_);
415		}
416	23x	return std::noop_coroutine();
417		}
418
419		inline std::coroutine_handle<>
420	13x	posix_resolver::reverse_resolve(
421		std::coroutine_handle<> h,
422		capy::executor_ref ex,
423		endpoint const& ep,
424		reverse_flags flags,
425		std::stop_token token,
426		std::error_code* ec,
427		reverse_resolver_result* result_out)
428		{
429	13x	if (svc_.resolver_unavailable())
430		{
431	1x	*ec = std::make_error_code(std::errc::operation_not_supported);
432	1x	reverse_op_.cont.h = h;
433	1x	return dispatch_coro(ex, reverse_op_.cont);
434		}
435
436	12x	auto& op = reverse_op_;
437	12x	op.reset();
438	12x	op.h = h;
439	12x	op.ex = ex;
440	12x	op.impl = this;
441	12x	op.ec_out = ec;
442	12x	op.result_out = result_out;
443	12x	op.ep = ep;
444	12x	op.flags = flags;
445	12x	op.start(token);
446
447		// Keep io_context alive while resolution is pending
448	12x	op.ex.on_work_started();
449
450		// Prevent impl destruction while work is in flight
451	12x	reverse_pool_op_.resolver_ = this;
452	12x	reverse_pool_op_.ref_ = this->shared_from_this();
453	12x	reverse_pool_op_.func_ = &posix_resolver::do_reverse_resolve_work;
454	12x	if (!svc_.pool().post(&reverse_pool_op_))
455		{
456		// Pool shut down — complete with cancellation
457	✗	reverse_pool_op_.ref_.reset();
458	✗	op.cancelled.store(true, std::memory_order_release);
459	✗	svc_.post(&reverse_op_);
460		}
461	12x	return std::noop_coroutine();
462		}
463
464		inline void
465	50x	posix_resolver::cancel() noexcept
466		{
467	50x	op_.request_cancel();
468	50x	reverse_op_.request_cancel();
469	50x	}
470
471		inline void
472	23x	posix_resolver::do_resolve_work(pool_work_item* w) noexcept
473		{
474	23x	auto* pw = static_cast<pool_op*>(w);
475	23x	auto* self = pw->resolver_;
476
477	23x	struct addrinfo hints{};
478	23x	hints.ai_family = AF_UNSPEC;
479	23x	hints.ai_socktype = SOCK_STREAM;
480	23x	hints.ai_flags = posix_resolver_detail::flags_to_hints(self->op_.flags);
481
482	23x	struct addrinfo* ai = nullptr;
483	69x	int result = ::getaddrinfo(
484	46x	self->op_.host.empty() ? nullptr : self->op_.host.c_str(),
485	46x	self->op_.service.empty() ? nullptr : self->op_.service.c_str(), &hints,
486		&ai);
487
488	23x	if (!self->op_.cancelled.load(std::memory_order_acquire))
489		{
490	22x	if (result == 0 && ai)
491		{
492	36x	self->op_.stored_results = posix_resolver_detail::convert_results(
493	18x	ai, self->op_.host, self->op_.service);
494	18x	self->op_.gai_error = 0;
495		}
496		else
497		{
498	4x	self->op_.gai_error = result;
499		}
500		}
501
502	23x	if (ai)
503	19x	::freeaddrinfo(ai);
504
505		// Move ref to stack before post — post may trigger destroy_impl
506		// which erases the last shared_ptr, destroying self (and pw)
507	23x	auto ref = std::move(pw->ref_);
508	23x	self->svc_.post(&self->op_);
509	23x	}
510
511		inline void
512	12x	posix_resolver::do_reverse_resolve_work(pool_work_item* w) noexcept
513		{
514	12x	auto* pw = static_cast<pool_op*>(w);
515	12x	auto* self = pw->resolver_;
516
517	12x	sockaddr_storage ss{};
518		socklen_t ss_len;
519
520	12x	if (self->reverse_op_.ep.is_v4())
521		{
522	10x	auto sa = to_sockaddr_in(self->reverse_op_.ep);
523	10x	std::memcpy(&ss, &sa, sizeof(sa));
524	10x	ss_len = sizeof(sockaddr_in);
525		}
526		else
527		{
528	2x	auto sa = to_sockaddr_in6(self->reverse_op_.ep);
529	2x	std::memcpy(&ss, &sa, sizeof(sa));
530	2x	ss_len = sizeof(sockaddr_in6);
531		}
532
533		char host[NI_MAXHOST];
534		char service[NI_MAXSERV];
535
536	12x	int result = ::getnameinfo(
537		reinterpret_cast<sockaddr*>(&ss), ss_len, host, sizeof(host), service,
538		sizeof(service),
539		posix_resolver_detail::flags_to_ni_flags(self->reverse_op_.flags));
540
541	12x	if (!self->reverse_op_.cancelled.load(std::memory_order_acquire))
542		{
543	11x	if (result == 0)
544		{
545	10x	self->reverse_op_.stored_host = host;
546	10x	self->reverse_op_.stored_service = service;
547	10x	self->reverse_op_.gai_error = 0;
548		}
549		else
550		{
551	1x	self->reverse_op_.gai_error = result;
552		}
553		}
554
555		// Move ref to stack before post — post may trigger destroy_impl
556		// which erases the last shared_ptr, destroying self (and pw)
557	12x	auto ref = std::move(pw->ref_);
558	12x	self->svc_.post(&self->reverse_op_);
559	12x	}
560
561		// posix_resolver_service implementation
562
563		inline void
564	1876x	posix_resolver_service::shutdown()
565		{
566	1876x	std::lock_guard<std::mutex> lock(mutex_);
567
568		// Cancel all resolvers (sets cancelled flag checked by pool threads)
569	1876x	for (auto* impl = resolver_list_.pop_front(); impl != nullptr;
570	✗	impl = resolver_list_.pop_front())
571		{
572	✗	impl->cancel();
573		}
574
575		// Clear the map which releases shared_ptrs.
576		// The thread pool service shuts down separately via
577		// execution_context service ordering.
578	1876x	resolver_ptrs_.clear();
579	1876x	}
580
581		inline io_object::implementation*
582	46x	posix_resolver_service::construct()
583		{
584	46x	auto ptr = std::make_shared<posix_resolver>(*this);
585	46x	auto* impl = ptr.get();
586
587		{
588	46x	std::lock_guard<std::mutex> lock(mutex_);
589	46x	resolver_list_.push_back(impl);
590	46x	resolver_ptrs_[impl] = std::move(ptr);
591	46x	}
592
593	46x	return impl;
594	46x	}
595
596		inline void
597	46x	posix_resolver_service::destroy_impl(posix_resolver& impl)
598		{
599	46x	std::lock_guard<std::mutex> lock(mutex_);
600	46x	resolver_list_.remove(&impl);
601	46x	resolver_ptrs_.erase(&impl);
602	46x	}
603
604		inline void
605	35x	posix_resolver_service::post(scheduler_op* op)
606		{
607	35x	sched_->post(op);
608	35x	}
609
610		inline void
611		posix_resolver_service::work_started() noexcept
612		{
613		sched_->work_started();
614		}
615
616		inline void
617	35x	posix_resolver_service::work_finished() noexcept
618		{
619	35x	sched_->work_finished();
620	35x	}
621
622		// Free function to get/create the resolver service
623
624		inline posix_resolver_service&
625	1876x	get_resolver_service(capy::execution_context& ctx, scheduler& sched)
626		{
627	1876x	return ctx.make_service<posix_resolver_service>(sched);
628		}
629
630		} // namespace boost::corosio::detail
631
632		#endif // BOOST_COROSIO_POSIX
633
634		#endif // BOOST_COROSIO_NATIVE_DETAIL_POSIX_POSIX_RESOLVER_SERVICE_HPP
635