TLA Line data Source code
1 : //
2 : // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3 : // Copyright (c) 2026 Steve Gerbino
4 : // Copyright (c) 2026 Michael Vandeberg
5 : //
6 : // Distributed under the Boost Software License, Version 1.0. (See accompanying
7 : // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
8 : //
9 : // Official repository: https://github.com/cppalliance/corosio
10 : //
11 :
12 : #ifndef BOOST_COROSIO_RESOLVER_HPP
13 : #define BOOST_COROSIO_RESOLVER_HPP
14 :
15 : #include <boost/corosio/detail/config.hpp>
16 : #include <boost/corosio/endpoint.hpp>
17 : #include <boost/corosio/io/io_object.hpp>
18 : #include <boost/capy/io_result.hpp>
19 : #include <boost/corosio/resolver_results.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 <cassert>
28 : #include <concepts>
29 : #include <coroutine>
30 : #include <stop_token>
31 : #include <string>
32 : #include <string_view>
33 : #include <type_traits>
34 :
35 : namespace boost::corosio {
36 :
37 : /** Bitmask flags for resolver queries.
38 :
39 : These flags correspond to the hints parameter of getaddrinfo.
40 : */
41 : enum class resolve_flags : unsigned int
42 : {
43 : /// No flags.
44 : none = 0,
45 :
46 : /// Indicate that returned endpoint is intended for use as a locally
47 : /// bound socket endpoint.
48 : passive = 0x01,
49 :
50 : /// Host name should be treated as a numeric string defining an IPv4
51 : /// or IPv6 address and no name resolution should be attempted.
52 : numeric_host = 0x04,
53 :
54 : /// Service name should be treated as a numeric string defining a port
55 : /// number and no name resolution should be attempted.
56 : numeric_service = 0x08,
57 :
58 : /// Only return IPv4 addresses if a non-loopback IPv4 address is
59 : /// configured for the system. Only return IPv6 addresses if a
60 : /// non-loopback IPv6 address is configured for the system.
61 : address_configured = 0x20,
62 :
63 : /// If the query protocol family is specified as IPv6, return
64 : /// IPv4-mapped IPv6 addresses on finding no IPv6 addresses.
65 : v4_mapped = 0x800,
66 :
67 : /// If used with v4_mapped, return all matching IPv6 and IPv4 addresses.
68 : all_matching = 0x100
69 : };
70 :
71 : /** Combine two resolve_flags. */
72 : inline resolve_flags
73 HIT 17 : operator|(resolve_flags a, resolve_flags b) noexcept
74 : {
75 : return static_cast<resolve_flags>(
76 17 : static_cast<unsigned int>(a) | static_cast<unsigned int>(b));
77 : }
78 :
79 : /** Combine two resolve_flags. */
80 : inline resolve_flags&
81 1 : operator|=(resolve_flags& a, resolve_flags b) noexcept
82 : {
83 1 : a = a | b;
84 1 : return a;
85 : }
86 :
87 : /** Intersect two resolve_flags. */
88 : inline resolve_flags
89 187 : operator&(resolve_flags a, resolve_flags b) noexcept
90 : {
91 : return static_cast<resolve_flags>(
92 187 : static_cast<unsigned int>(a) & static_cast<unsigned int>(b));
93 : }
94 :
95 : /** Intersect two resolve_flags. */
96 : inline resolve_flags&
97 1 : operator&=(resolve_flags& a, resolve_flags b) noexcept
98 : {
99 1 : a = a & b;
100 1 : return a;
101 : }
102 :
103 : /** Bitmask flags for reverse resolver queries.
104 :
105 : These flags correspond to the flags parameter of getnameinfo.
106 : */
107 : enum class reverse_flags : unsigned int
108 : {
109 : /// No flags.
110 : none = 0,
111 :
112 : /// Return the numeric form of the hostname instead of its name.
113 : numeric_host = 0x01,
114 :
115 : /// Return the numeric form of the service name instead of its name.
116 : numeric_service = 0x02,
117 :
118 : /// Return an error if the hostname cannot be resolved.
119 : name_required = 0x04,
120 :
121 : /// Lookup for datagram (UDP) service instead of stream (TCP).
122 : datagram_service = 0x08
123 : };
124 :
125 : /** Combine two reverse_flags. */
126 : inline reverse_flags
127 9 : operator|(reverse_flags a, reverse_flags b) noexcept
128 : {
129 : return static_cast<reverse_flags>(
130 9 : static_cast<unsigned int>(a) | static_cast<unsigned int>(b));
131 : }
132 :
133 : /** Combine two reverse_flags. */
134 : inline reverse_flags&
135 1 : operator|=(reverse_flags& a, reverse_flags b) noexcept
136 : {
137 1 : a = a | b;
138 1 : return a;
139 : }
140 :
141 : /** Intersect two reverse_flags. */
142 : inline reverse_flags
143 79 : operator&(reverse_flags a, reverse_flags b) noexcept
144 : {
145 : return static_cast<reverse_flags>(
146 79 : static_cast<unsigned int>(a) & static_cast<unsigned int>(b));
147 : }
148 :
149 : /** Intersect two reverse_flags. */
150 : inline reverse_flags&
151 1 : operator&=(reverse_flags& a, reverse_flags b) noexcept
152 : {
153 1 : a = a & b;
154 1 : return a;
155 : }
156 :
157 : /** An asynchronous DNS resolver for coroutine I/O.
158 :
159 : This class provides asynchronous DNS resolution operations that return
160 : awaitable types. Each operation participates in the affine awaitable
161 : protocol, ensuring coroutines resume on the correct executor.
162 :
163 : @par Thread Safety
164 : Distinct objects: Safe.@n
165 : Shared objects: Unsafe. A resolver must not have concurrent resolve
166 : operations.
167 :
168 : @par Semantics
169 : Wraps platform DNS resolution (getaddrinfo/getnameinfo).
170 : Operations dispatch to OS resolver APIs via the io_context
171 : thread pool.
172 :
173 : @par Example
174 : @par !example resolver
175 : */
176 : class BOOST_COROSIO_DECL resolver : public io_object
177 : {
178 : struct resolve_awaitable
179 : {
180 : resolver& r_;
181 : std::string host_;
182 : std::string service_;
183 : resolve_flags flags_;
184 : std::stop_token token_;
185 : mutable std::error_code ec_;
186 : mutable resolver_results results_;
187 :
188 30 : resolve_awaitable(
189 : resolver& r,
190 : std::string_view host,
191 : std::string_view service,
192 : resolve_flags flags) noexcept
193 30 : : r_(r)
194 60 : , host_(host)
195 60 : , service_(service)
196 30 : , flags_(flags)
197 : {
198 30 : }
199 :
200 30 : bool await_ready() const noexcept
201 : {
202 30 : return token_.stop_requested();
203 : }
204 :
205 29 : [[nodiscard]] capy::io_result<resolver_results> await_resume() const noexcept
206 : {
207 29 : if (token_.stop_requested())
208 1 : return {make_error_code(std::errc::operation_canceled), {}};
209 28 : return {ec_, std::move(results_)};
210 : }
211 :
212 30 : auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
213 : -> std::coroutine_handle<>
214 : {
215 30 : token_ = env->stop_token;
216 90 : return r_.get().resolve(
217 30 : h, env->executor, host_, service_, flags_, token_, &ec_,
218 60 : &results_);
219 : }
220 : };
221 :
222 : struct reverse_resolve_awaitable
223 : {
224 : resolver& r_;
225 : endpoint ep_;
226 : reverse_flags flags_;
227 : std::stop_token token_;
228 : mutable std::error_code ec_;
229 : mutable reverse_resolver_result result_;
230 :
231 20 : reverse_resolve_awaitable(
232 : resolver& r, endpoint const& ep, reverse_flags flags) noexcept
233 20 : : r_(r)
234 20 : , ep_(ep)
235 20 : , flags_(flags)
236 : {
237 20 : }
238 :
239 20 : bool await_ready() const noexcept
240 : {
241 20 : return token_.stop_requested();
242 : }
243 :
244 19 : [[nodiscard]] capy::io_result<reverse_resolver_result> await_resume() const noexcept
245 : {
246 19 : if (token_.stop_requested())
247 1 : return {make_error_code(std::errc::operation_canceled), {}};
248 18 : return {ec_, std::move(result_)};
249 : }
250 :
251 20 : auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
252 : -> std::coroutine_handle<>
253 : {
254 20 : token_ = env->stop_token;
255 40 : return r_.get().reverse_resolve(
256 40 : h, env->executor, ep_, flags_, token_, &ec_, &result_);
257 : }
258 : };
259 :
260 : public:
261 : /** Destructor.
262 :
263 : Cancels any pending operations.
264 : */
265 : ~resolver() override;
266 :
267 : /** Construct a resolver from an execution context.
268 :
269 : @param ctx The execution context that will own this resolver.
270 : */
271 : explicit resolver(capy::execution_context& ctx);
272 :
273 : /** Construct a resolver from an executor.
274 :
275 : The resolver is associated with the executor's context.
276 :
277 : @param ex The executor whose context will own the resolver.
278 : */
279 : template<class Ex>
280 : requires(!std::same_as<std::remove_cvref_t<Ex>, resolver>) &&
281 : capy::Executor<Ex>
282 1 : explicit resolver(Ex const& ex) : resolver(ex.context())
283 : {
284 1 : }
285 :
286 : /** Move constructor.
287 :
288 : Transfers ownership of the resolver resources. After the move,
289 : @p other is in a moved-from state and may only be destroyed or
290 : assigned to.
291 :
292 : @param other The resolver to move from.
293 :
294 : @pre No awaitables returned by @p other's `resolve` methods
295 : exist.
296 : @pre The execution context associated with @p other must
297 : outlive this resolver.
298 : */
299 2 : resolver(resolver&& other) noexcept : io_object(std::move(other)) {}
300 :
301 : /** Move assignment operator.
302 :
303 : Destroys the current implementation and transfers ownership
304 : from @p other. After the move, @p other is in a moved-from
305 : state and may only be destroyed or assigned to.
306 :
307 : @param other The resolver to move from.
308 :
309 : @pre No awaitables returned by either `*this` or @p other's
310 : `resolve` methods exist.
311 : @pre The execution context associated with @p other must
312 : outlive this resolver.
313 :
314 : @return Reference to this resolver.
315 : */
316 2 : resolver& operator=(resolver&& other) noexcept
317 : {
318 2 : if (this != &other)
319 2 : h_ = std::move(other.h_);
320 2 : return *this;
321 : }
322 :
323 : resolver(resolver const&) = delete;
324 : resolver& operator=(resolver const&) = delete;
325 :
326 : /** Initiate an asynchronous resolve operation.
327 :
328 : Resolves the host and service names into a list of endpoints.
329 :
330 : This resolver must outlive the returned awaitable.
331 :
332 : @param host A string identifying a location. May be a descriptive
333 : name or a numeric address string.
334 :
335 : @param service A string identifying the requested service. This may
336 : be a descriptive name or a numeric string corresponding to a
337 : port number.
338 :
339 : @return An awaitable that completes with `io_result<resolver_results>`.
340 :
341 : @note `resolver_results` is an alias for `std::vector<resolver_entry>`.
342 : Copying it deep-copies every entry (each owns two `std::string`s);
343 : move it (`std::move(results)`) or pass iterators when handing it to
344 : a by-value sink such as @ref connect.
345 :
346 : @par Example
347 : @par !example forward_resolve
348 : */
349 14 : [[nodiscard]] auto resolve(std::string_view host, std::string_view service)
350 : {
351 14 : return resolve_awaitable(*this, host, service, resolve_flags::none);
352 : }
353 :
354 : /** Initiate an asynchronous resolve operation with flags.
355 :
356 : Resolves the host and service names into a list of endpoints.
357 :
358 : This resolver must outlive the returned awaitable.
359 :
360 : @param host A string identifying a location.
361 :
362 : @param service A string identifying the requested service.
363 :
364 : @param flags Flags controlling resolution behavior.
365 :
366 : @return An awaitable that completes with `io_result<resolver_results>`.
367 : */
368 16 : [[nodiscard]] auto resolve(
369 : std::string_view host, std::string_view service, resolve_flags flags)
370 : {
371 16 : return resolve_awaitable(*this, host, service, flags);
372 : }
373 :
374 : /** Initiate an asynchronous reverse resolve operation.
375 :
376 : Resolves an endpoint into a hostname and service name using
377 : reverse DNS lookup (PTR record query).
378 :
379 : This resolver must outlive the returned awaitable.
380 :
381 : @param ep The endpoint to resolve.
382 :
383 : @return An awaitable that completes with
384 : `io_result<reverse_resolver_result>`.
385 :
386 : @par Example
387 : @par !example reverse_resolve
388 : */
389 11 : [[nodiscard]] auto resolve(endpoint const& ep)
390 : {
391 11 : return reverse_resolve_awaitable(*this, ep, reverse_flags::none);
392 : }
393 :
394 : /** Initiate an asynchronous reverse resolve operation with flags.
395 :
396 : Resolves an endpoint into a hostname and service name using
397 : reverse DNS lookup (PTR record query).
398 :
399 : This resolver must outlive the returned awaitable.
400 :
401 : @param ep The endpoint to resolve.
402 :
403 : @param flags Flags controlling resolution behavior. See reverse_flags.
404 :
405 : @return An awaitable that completes with
406 : `io_result<reverse_resolver_result>`.
407 : */
408 9 : [[nodiscard]] auto resolve(endpoint const& ep, reverse_flags flags)
409 : {
410 9 : return reverse_resolve_awaitable(*this, ep, flags);
411 : }
412 :
413 : /** Cancel any pending asynchronous operations.
414 :
415 : All outstanding operations complete with `errc::operation_canceled`.
416 : Check `ec == cond::canceled` for portable comparison.
417 : */
418 : void cancel() noexcept;
419 :
420 : public:
421 : /** Backend interface for DNS resolution operations.
422 :
423 : Platform backends derive from this to implement forward and
424 : reverse DNS resolution via getaddrinfo/getnameinfo.
425 : */
426 : struct implementation : io_object::implementation
427 : {
428 : /// Initiate an asynchronous forward DNS resolution.
429 : virtual std::coroutine_handle<> resolve(
430 : std::coroutine_handle<>,
431 : capy::executor_ref,
432 : std::string_view host,
433 : std::string_view service,
434 : resolve_flags flags,
435 : std::stop_token,
436 : std::error_code*,
437 : resolver_results*) = 0;
438 :
439 : /// Initiate an asynchronous reverse DNS resolution.
440 : virtual std::coroutine_handle<> reverse_resolve(
441 : std::coroutine_handle<>,
442 : capy::executor_ref,
443 : endpoint const& ep,
444 : reverse_flags flags,
445 : std::stop_token,
446 : std::error_code*,
447 : reverse_resolver_result*) = 0;
448 :
449 : /// Cancel pending resolve operations.
450 : virtual void cancel() noexcept = 0;
451 : };
452 :
453 : protected:
454 : explicit resolver(handle h) noexcept : io_object(std::move(h)) {}
455 :
456 : private:
457 57 : inline implementation& get() const noexcept
458 : {
459 57 : return *static_cast<implementation*>(h_.get());
460 : }
461 : };
462 :
463 : } // namespace boost::corosio
464 :
465 : #endif
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