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/detail/op_base.hpp>
17 : #include <boost/corosio/endpoint.hpp>
18 : #include <boost/corosio/io/io_object.hpp>
19 : #include <boost/capy/io_result.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 <vector>
34 : #include <type_traits>
35 :
36 : namespace boost::corosio {
37 :
38 : /** Bitmask flags for resolver queries.
39 :
40 : These flags correspond to the hints parameter of getaddrinfo.
41 : */
42 : enum class resolve_flags : unsigned int
43 : {
44 : /// No flags.
45 : none = 0,
46 :
47 : /// Indicate that returned endpoint is intended for use as a locally
48 : /// bound socket endpoint.
49 : passive = 0x01,
50 :
51 : /// Host name should be treated as a numeric string defining an IPv4
52 : /// or IPv6 address and no name resolution should be attempted.
53 : numeric_host = 0x04,
54 :
55 : /// Service name should be treated as a numeric string defining a port
56 : /// number and no name resolution should be attempted.
57 : numeric_service = 0x08,
58 :
59 : /// Only return IPv4 addresses if a non-loopback IPv4 address is
60 : /// configured for the system. Only return IPv6 addresses if a
61 : /// non-loopback IPv6 address is configured for the system.
62 : address_configured = 0x20,
63 :
64 : /// If the query protocol family is specified as IPv6, return
65 : /// IPv4-mapped IPv6 addresses on finding no IPv6 addresses.
66 : v4_mapped = 0x800,
67 :
68 : /// If used with v4_mapped, return all matching IPv6 and IPv4 addresses.
69 : all_matching = 0x100
70 : };
71 :
72 : /** Combine two resolve_flags. */
73 : inline resolve_flags
74 HIT 17 : operator|(resolve_flags a, resolve_flags b) noexcept
75 : {
76 : return static_cast<resolve_flags>(
77 17 : static_cast<unsigned int>(a) | static_cast<unsigned int>(b));
78 : }
79 :
80 : /** Combine two resolve_flags. */
81 : inline resolve_flags&
82 1 : operator|=(resolve_flags& a, resolve_flags b) noexcept
83 : {
84 1 : a = a | b;
85 1 : return a;
86 : }
87 :
88 : /** Intersect two resolve_flags. */
89 : inline resolve_flags
90 205 : operator&(resolve_flags a, resolve_flags b) noexcept
91 : {
92 : return static_cast<resolve_flags>(
93 205 : static_cast<unsigned int>(a) & static_cast<unsigned int>(b));
94 : }
95 :
96 : /** Intersect two resolve_flags. */
97 : inline resolve_flags&
98 1 : operator&=(resolve_flags& a, resolve_flags b) noexcept
99 : {
100 1 : a = a & b;
101 1 : return a;
102 : }
103 :
104 : /** Bitmask flags for reverse resolver queries.
105 :
106 : These flags correspond to the flags parameter of getnameinfo.
107 : */
108 : enum class reverse_flags : unsigned int
109 : {
110 : /// No flags.
111 : none = 0,
112 :
113 : /// Return the numeric form of the hostname instead of its name.
114 : numeric_host = 0x01,
115 :
116 : /// Return the numeric form of the service name instead of its name.
117 : numeric_service = 0x02,
118 :
119 : /// Return an error if the hostname cannot be resolved.
120 : name_required = 0x04,
121 :
122 : /// Lookup for datagram (UDP) service instead of stream (TCP).
123 : datagram_service = 0x08
124 : };
125 :
126 : /** Combine two reverse_flags. */
127 : inline reverse_flags
128 9 : operator|(reverse_flags a, reverse_flags b) noexcept
129 : {
130 : return static_cast<reverse_flags>(
131 9 : static_cast<unsigned int>(a) | static_cast<unsigned int>(b));
132 : }
133 :
134 : /** Combine two reverse_flags. */
135 : inline reverse_flags&
136 1 : operator|=(reverse_flags& a, reverse_flags b) noexcept
137 : {
138 1 : a = a | b;
139 1 : return a;
140 : }
141 :
142 : /** Intersect two reverse_flags. */
143 : inline reverse_flags
144 75 : operator&(reverse_flags a, reverse_flags b) noexcept
145 : {
146 : return static_cast<reverse_flags>(
147 75 : static_cast<unsigned int>(a) & static_cast<unsigned int>(b));
148 : }
149 :
150 : /** Intersect two reverse_flags. */
151 : inline reverse_flags&
152 1 : operator&=(reverse_flags& a, reverse_flags b) noexcept
153 : {
154 1 : a = a & b;
155 1 : return a;
156 : }
157 :
158 : /** The name of an endpoint.
159 :
160 : Reverse resolution translates an endpoint into its symbolic
161 : spelling: the host name and the service name. Both fields carry
162 : resolved data; the endpoint they name is the one the caller
163 : passed to `resolve`.
164 : */
165 : struct endpoint_name
166 : {
167 : /// The resolved host name.
168 : std::string host_name;
169 :
170 : /// The resolved service name.
171 : std::string service_name;
172 : };
173 :
174 : /** An asynchronous DNS resolver for coroutine I/O.
175 :
176 : This class provides asynchronous DNS resolution operations that return
177 : awaitable types. Each operation participates in the affine awaitable
178 : protocol, ensuring coroutines resume on the correct executor.
179 :
180 : @par Thread Safety
181 : Distinct objects: Safe.@n
182 : Shared objects: Unsafe. A resolver must not have concurrent resolve
183 : operations.
184 :
185 : @par Semantics
186 : Wraps platform DNS resolution (getaddrinfo/getnameinfo).
187 : Operations dispatch to OS resolver APIs via the io_context
188 : thread pool.
189 :
190 : @par Example
191 : @par !example resolver
192 : */
193 : class BOOST_COROSIO_DECL resolver : public io_object
194 : {
195 : struct resolve_awaitable
196 : : detail::value_op_base<resolve_awaitable, std::vector<endpoint>>
197 : {
198 : resolver& r_;
199 : std::string host_;
200 : std::string service_;
201 : resolve_flags flags_;
202 :
203 29 : resolve_awaitable(
204 : resolver& r,
205 : std::string_view host,
206 : std::string_view service,
207 : resolve_flags flags) noexcept
208 58 : : r_(r)
209 58 : , host_(host)
210 58 : , service_(service)
211 29 : , flags_(flags)
212 : {
213 29 : }
214 :
215 : std::coroutine_handle<>
216 28 : dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
217 : {
218 84 : return r_.get().resolve(
219 84 : h, ex, host_, service_, flags_, token_, &ec_, &value_);
220 : }
221 : };
222 :
223 : struct resolve_host_awaitable
224 : : detail::value_op_base<resolve_host_awaitable, std::vector<endpoint>>
225 : {
226 : resolver& r_;
227 : std::string host_;
228 : resolve_flags flags_;
229 :
230 6 : resolve_host_awaitable(
231 : resolver& r, std::string_view host, resolve_flags flags) noexcept
232 12 : : r_(r)
233 12 : , host_(host)
234 6 : , flags_(flags)
235 : {
236 6 : }
237 :
238 : std::coroutine_handle<>
239 5 : dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
240 : {
241 : // An empty service reaches the system resolver as null,
242 : // which is the host-only query
243 15 : return r_.get().resolve(
244 15 : h, ex, host_, {}, flags_, token_, &ec_, &value_);
245 : }
246 :
247 : // Shadows the base: the endpoint result is reshaped into
248 : // the honest address list
249 : [[nodiscard]] capy::io_result<std::vector<ip_address>>
250 6 : await_resume() const
251 : {
252 6 : std::vector<ip_address> addrs;
253 6 : addrs.reserve(value_.size());
254 9 : for (auto const& entry : value_)
255 : {
256 3 : auto a = entry.address();
257 3 : bool duplicate = false;
258 3 : for (auto const& seen : addrs)
259 : {
260 MIS 0 : if (seen == a)
261 : {
262 0 : duplicate = true;
263 0 : break;
264 : }
265 : }
266 : // The same address can come back more than once
267 : // (mixed name sources, repeated records); each
268 : // address is reported once
269 HIT 3 : if (!duplicate)
270 3 : addrs.push_back(a);
271 : }
272 12 : return {ec_, std::move(addrs)};
273 6 : }
274 : };
275 :
276 : struct reverse_resolve_awaitable
277 : : detail::value_op_base<reverse_resolve_awaitable, endpoint_name>
278 : {
279 : resolver& r_;
280 : endpoint ep_;
281 : reverse_flags flags_;
282 :
283 20 : reverse_resolve_awaitable(
284 : resolver& r, endpoint const& ep, reverse_flags flags) noexcept
285 40 : : r_(r)
286 20 : , ep_(ep)
287 20 : , flags_(flags)
288 : {
289 20 : }
290 :
291 : std::coroutine_handle<>
292 19 : dispatch(std::coroutine_handle<> h, capy::executor_ref ex) const
293 : {
294 38 : return r_.get().reverse_resolve(
295 38 : h, ex, ep_, flags_, token_, &ec_, &value_);
296 : }
297 : };
298 :
299 : public:
300 : /** Destructor.
301 :
302 : Cancels any pending operations.
303 : */
304 : ~resolver() override;
305 :
306 : /** Construct a resolver from an execution context.
307 :
308 : @param ctx The execution context that will own this resolver.
309 : */
310 : explicit resolver(capy::execution_context& ctx);
311 :
312 : /** Construct a resolver from an executor.
313 :
314 : The resolver is associated with the executor's context.
315 :
316 : @param ex The executor whose context will own the resolver.
317 : */
318 : template<class Ex>
319 : requires(!std::same_as<std::remove_cvref_t<Ex>, resolver>) &&
320 : capy::Executor<Ex>
321 1 : explicit resolver(Ex const& ex) : resolver(ex.context())
322 : {
323 1 : }
324 :
325 : /** Move constructor.
326 :
327 : Transfers ownership of the resolver resources. After the move,
328 : @p other is in a moved-from state and may only be destroyed or
329 : assigned to.
330 :
331 : @param other The resolver to move from.
332 :
333 : @pre No awaitables returned by @p other's `resolve` methods
334 : exist.
335 : @pre The execution context associated with @p other must
336 : outlive this resolver.
337 : */
338 2 : resolver(resolver&& other) noexcept : io_object(std::move(other)) {}
339 :
340 : /** Move assignment operator.
341 :
342 : Destroys the current implementation and transfers ownership
343 : from @p other. After the move, @p other is in a moved-from
344 : state and may only be destroyed or assigned to.
345 :
346 : @param other The resolver to move from.
347 :
348 : @pre No awaitables returned by either `*this` or @p other's
349 : `resolve` methods exist.
350 : @pre The execution context associated with @p other must
351 : outlive this resolver.
352 :
353 : @return Reference to this resolver.
354 : */
355 2 : resolver& operator=(resolver&& other) noexcept
356 : {
357 2 : if (this != &other)
358 2 : h_ = std::move(other.h_);
359 2 : return *this;
360 : }
361 :
362 : resolver(resolver const&) = delete;
363 : resolver& operator=(resolver const&) = delete;
364 :
365 : /** Initiate an asynchronous resolve operation.
366 :
367 : Resolves the host and service names into a list of endpoints.
368 :
369 : This resolver must outlive the returned awaitable.
370 :
371 : @param host A string identifying a location. May be a descriptive
372 : name or a numeric address string.
373 :
374 : @param service A string identifying the requested service. This may
375 : be a descriptive name or a numeric string corresponding to a
376 : port number.
377 :
378 : @return An awaitable that completes with
379 : `io_result<std::vector<endpoint>>`.
380 :
381 : @par Example
382 : @par !example forward_resolve
383 : */
384 13 : [[nodiscard]] auto resolve(std::string_view host, std::string_view service)
385 : {
386 13 : return resolve_awaitable(*this, host, service, resolve_flags::none);
387 : }
388 :
389 : /** Initiate an asynchronous host-only resolve operation.
390 :
391 : Resolves a host name into its addresses, with no service or
392 : port involved — the query `getaddrinfo` performs with a null
393 : service. Use this when the host and port travel separately,
394 : as they do in most configuration.
395 :
396 : Each address appears once in the result even when the query
397 : reports it more than once, and link-local results keep
398 : their zone.
399 :
400 : @param host The host name or numeric address string.
401 :
402 : @return An awaitable that completes with
403 : `io_result<std::vector<ip_address>>`.
404 :
405 : @par Example
406 : @par !example host_only_resolve
407 : */
408 3 : [[nodiscard]] auto resolve(std::string_view host)
409 : {
410 3 : return resolve_host_awaitable(*this, host, resolve_flags::none);
411 : }
412 :
413 : /** Initiate an asynchronous host-only resolve operation with flags.
414 :
415 : @param host The host name or numeric address string.
416 : @param flags Resolution behavior flags.
417 :
418 : @return An awaitable that completes with
419 : `io_result<std::vector<ip_address>>`.
420 : */
421 3 : [[nodiscard]] auto resolve(std::string_view host, resolve_flags flags)
422 : {
423 3 : return resolve_host_awaitable(*this, host, flags);
424 : }
425 :
426 : /** Initiate an asynchronous resolve operation with flags.
427 :
428 : Resolves the host and service names into a list of endpoints.
429 :
430 : This resolver must outlive the returned awaitable.
431 :
432 : @param host A string identifying a location.
433 :
434 : @param service A string identifying the requested service.
435 :
436 : @param flags Flags controlling resolution behavior.
437 :
438 : @return An awaitable that completes with
439 : `io_result<std::vector<endpoint>>`.
440 : */
441 16 : [[nodiscard]] auto resolve(
442 : std::string_view host, std::string_view service, resolve_flags flags)
443 : {
444 16 : return resolve_awaitable(*this, host, service, flags);
445 : }
446 :
447 : /** Initiate an asynchronous reverse resolve operation.
448 :
449 : Resolves an endpoint into a hostname and service name using
450 : reverse DNS lookup (PTR record query).
451 :
452 : This resolver must outlive the returned awaitable.
453 :
454 : @param ep The endpoint to resolve.
455 :
456 : @return An awaitable that completes with
457 : `io_result<endpoint_name>`.
458 :
459 : @par Example
460 : @par !example reverse_resolve
461 : */
462 11 : [[nodiscard]] auto resolve(endpoint const& ep)
463 : {
464 11 : return reverse_resolve_awaitable(*this, ep, reverse_flags::none);
465 : }
466 :
467 : /** Initiate an asynchronous reverse resolve operation with flags.
468 :
469 : Resolves an endpoint into a hostname and service name using
470 : reverse DNS lookup (PTR record query).
471 :
472 : This resolver must outlive the returned awaitable.
473 :
474 : @param ep The endpoint to resolve.
475 :
476 : @param flags Flags controlling resolution behavior. See reverse_flags.
477 :
478 : @return An awaitable that completes with
479 : `io_result<endpoint_name>`.
480 : */
481 9 : [[nodiscard]] auto resolve(endpoint const& ep, reverse_flags flags)
482 : {
483 9 : return reverse_resolve_awaitable(*this, ep, flags);
484 : }
485 :
486 : /** Cancel any pending asynchronous operations.
487 :
488 : Operations still in flight complete with `errc::operation_canceled`;
489 : an operation whose result is already decided reports that result.
490 : Check `ec == cond::canceled` for portable comparison.
491 : */
492 : void cancel() noexcept;
493 :
494 : public:
495 : /** Backend interface for DNS resolution operations.
496 :
497 : Platform backends derive from this to implement forward and
498 : reverse DNS resolution via getaddrinfo/getnameinfo.
499 : */
500 : struct implementation : io_object::implementation
501 : {
502 : /// Initiate an asynchronous forward DNS resolution.
503 : virtual std::coroutine_handle<> resolve(
504 : std::coroutine_handle<>,
505 : capy::executor_ref,
506 : std::string_view host,
507 : std::string_view service,
508 : resolve_flags flags,
509 : std::stop_token,
510 : std::error_code*,
511 : std::vector<endpoint>*) = 0;
512 :
513 : /// Initiate an asynchronous reverse DNS resolution.
514 : virtual std::coroutine_handle<> reverse_resolve(
515 : std::coroutine_handle<>,
516 : capy::executor_ref,
517 : endpoint const& ep,
518 : reverse_flags flags,
519 : std::stop_token,
520 : std::error_code*,
521 : endpoint_name*) = 0;
522 :
523 : /// Cancel pending resolve operations.
524 : virtual void cancel() noexcept = 0;
525 : };
526 :
527 : protected:
528 : explicit resolver(handle h) noexcept : io_object(std::move(h)) {}
529 :
530 : private:
531 59 : inline implementation& get() const noexcept
532 : {
533 59 : return *static_cast<implementation*>(h_.get());
534 : }
535 : };
536 :
537 : } // namespace boost::corosio
538 :
539 : #endif
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