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/results.hpp>
20 : #include <boost/capy/ex/executor_ref.hpp>
21 : #include <boost/capy/ex/execution_context.hpp>
22 : #include <boost/capy/ex/await_context.hpp>
23 : #include <boost/capy/concept/executor.hpp>
24 :
25 : #include <system_error>
26 :
27 : #include <cassert>
28 : #include <concepts>
29 : #include <boost/capy/continuation.hpp>
30 :
31 : #include <coroutine>
32 : #include <stop_token>
33 : #include <string>
34 : #include <string_view>
35 : #include <vector>
36 : #include <type_traits>
37 :
38 : namespace boost::corosio {
39 :
40 : /** Bitmask flags for resolver queries.
41 :
42 : These flags correspond to the hints parameter of `getaddrinfo`.
43 : */
44 : enum class resolve_flags : unsigned int
45 : {
46 : /// No flags.
47 : none = 0,
48 :
49 : /// Indicate that returned endpoint is intended for use as a locally
50 : /// bound socket endpoint.
51 : passive = 0x01,
52 :
53 : /// Host name should be treated as a numeric string defining an IPv4
54 : /// or IPv6 address and no name resolution should be attempted.
55 : numeric_host = 0x04,
56 :
57 : /// Service name should be treated as a numeric string defining a port
58 : /// number and no name resolution should be attempted.
59 : numeric_service = 0x08,
60 :
61 : /// Only return IPv4 addresses if a non-loopback IPv4 address is
62 : /// configured for the system. Only return IPv6 addresses if a
63 : /// non-loopback IPv6 address is configured for the system.
64 : address_configured = 0x20,
65 :
66 : /// If the query protocol family is specified as IPv6, return
67 : /// IPv4-mapped IPv6 addresses on finding no IPv6 addresses.
68 : v4_mapped = 0x800,
69 :
70 : /// If used with v4_mapped, return all matching IPv6 and IPv4 addresses.
71 : all_matching = 0x100
72 : };
73 :
74 : /** Combine two `resolve_flags`. */
75 : inline resolve_flags
76 HIT 23 : operator|(resolve_flags a, resolve_flags b) noexcept
77 : {
78 : return static_cast<resolve_flags>(
79 23 : static_cast<unsigned int>(a) | static_cast<unsigned int>(b));
80 : }
81 :
82 : /** Combine two `resolve_flags`. */
83 : inline resolve_flags&
84 1 : operator|=(resolve_flags& a, resolve_flags b) noexcept
85 : {
86 1 : a = a | b;
87 1 : return a;
88 : }
89 :
90 : /** Intersect two `resolve_flags`. */
91 : inline resolve_flags
92 235 : operator&(resolve_flags a, resolve_flags b) noexcept
93 : {
94 : return static_cast<resolve_flags>(
95 235 : static_cast<unsigned int>(a) & static_cast<unsigned int>(b));
96 : }
97 :
98 : /** Intersect two `resolve_flags`. */
99 : inline resolve_flags&
100 1 : operator&=(resolve_flags& a, resolve_flags b) noexcept
101 : {
102 1 : a = a & b;
103 1 : return a;
104 : }
105 :
106 : /** Bitmask flags for reverse resolver queries.
107 :
108 : These flags correspond to the flags parameter of `getnameinfo`.
109 : */
110 : enum class reverse_flags : unsigned int
111 : {
112 : /// No flags.
113 : none = 0,
114 :
115 : /// Return the numeric form of the hostname instead of its name.
116 : numeric_host = 0x01,
117 :
118 : /// Return the numeric form of the service name instead of its name.
119 : numeric_service = 0x02,
120 :
121 : /// Return an error if the hostname cannot be resolved.
122 : name_required = 0x04,
123 :
124 : /// Lookup for datagram (UDP) service instead of stream (TCP).
125 : datagram_service = 0x08
126 : };
127 :
128 : /** Combine two `reverse_flags`. */
129 : inline reverse_flags
130 11 : operator|(reverse_flags a, reverse_flags b) noexcept
131 : {
132 : return static_cast<reverse_flags>(
133 11 : static_cast<unsigned int>(a) | static_cast<unsigned int>(b));
134 : }
135 :
136 : /** Combine two `reverse_flags`. */
137 : inline reverse_flags&
138 1 : operator|=(reverse_flags& a, reverse_flags b) noexcept
139 : {
140 1 : a = a | b;
141 1 : return a;
142 : }
143 :
144 : /** Intersect two `reverse_flags`. */
145 : inline reverse_flags
146 71 : operator&(reverse_flags a, reverse_flags b) noexcept
147 : {
148 : return static_cast<reverse_flags>(
149 71 : static_cast<unsigned int>(a) & static_cast<unsigned int>(b));
150 : }
151 :
152 : /** Intersect two `reverse_flags`. */
153 : inline reverse_flags&
154 1 : operator&=(reverse_flags& a, reverse_flags b) noexcept
155 : {
156 1 : a = a & b;
157 1 : return a;
158 : }
159 :
160 : /** The name of an endpoint.
161 :
162 : Reverse resolution translates an endpoint into its symbolic
163 : spelling: the host name and the service name. Both fields carry
164 : resolved data; the endpoint they name is the one the caller
165 : passed to `resolve`.
166 : */
167 : struct endpoint_name
168 : {
169 : /// The resolved host name.
170 : std::string host_name;
171 :
172 : /// The resolved service name.
173 : std::string service_name;
174 : };
175 :
176 : /** Resolves host names and services to endpoints, from a coroutine.
177 :
178 : This class provides asynchronous DNS resolution operations that return
179 : awaitable types. Each operation participates in the affine awaitable
180 : protocol, ensuring coroutines resume on the correct executor.
181 :
182 : @par Thread Safety
183 : Distinct objects: Safe.@n
184 : Shared objects: Unsafe. A resolver must not have concurrent resolve
185 : operations.
186 :
187 : @par Semantics
188 : Wraps platform DNS resolution (`getaddrinfo`/`getnameinfo`).
189 : Operations dispatch to OS resolver APIs via the `io_context`
190 : thread pool.
191 :
192 : @par Example
193 : @par !example resolver
194 : */
195 : class BOOST_COROSIO_DECL resolver : public io_object
196 : {
197 : struct resolve_awaitable
198 : : detail::value_op_base<resolve_awaitable, std::vector<endpoint>>
199 : {
200 : private:
201 : friend resolver;
202 :
203 37 : resolve_awaitable(
204 : resolver& r,
205 : std::string_view host,
206 : std::string_view service,
207 : resolve_flags flags) noexcept
208 74 : : r_(r)
209 74 : , host_(host)
210 74 : , service_(service)
211 37 : , flags_(flags)
212 : {
213 37 : }
214 :
215 : friend detail::value_op_base<resolve_awaitable, std::vector<endpoint>>;
216 : resolver& r_;
217 : std::string host_;
218 : std::string service_;
219 : resolve_flags flags_;
220 :
221 : std::coroutine_handle<>
222 36 : dispatch(capy::continuation& cont, capy::executor_ref ex) const
223 : {
224 108 : return r_.get().resolve(
225 108 : cont, ex, host_, service_, flags_, token_, &ec_, &value_);
226 : }
227 : };
228 :
229 : struct resolve_host_awaitable
230 : : detail::value_op_base<resolve_host_awaitable, std::vector<endpoint>>
231 : {
232 : private:
233 : friend resolver;
234 :
235 6 : resolve_host_awaitable(
236 : resolver& r, std::string_view host, resolve_flags flags) noexcept
237 12 : : r_(r)
238 12 : , host_(host)
239 6 : , flags_(flags)
240 : {
241 6 : }
242 :
243 : friend detail::
244 : value_op_base<resolve_host_awaitable, std::vector<endpoint>>;
245 : resolver& r_;
246 : std::string host_;
247 : resolve_flags flags_;
248 :
249 : std::coroutine_handle<>
250 5 : dispatch(capy::continuation& cont, capy::executor_ref ex) const
251 : {
252 : // An empty service reaches the system resolver as null,
253 : // which is the host-only query
254 15 : return r_.get().resolve(
255 15 : cont, ex, host_, {}, flags_, token_, &ec_, &value_);
256 : }
257 :
258 : public:
259 : // Shadows the base: the endpoint result is reshaped into
260 : // the honest address list
261 : [[nodiscard]] capy::results<std::vector<ip_address>>
262 6 : await_resume() const
263 : {
264 6 : std::vector<ip_address> addrs;
265 6 : addrs.reserve(value_.size());
266 9 : for (auto const& entry : value_)
267 : {
268 3 : auto a = entry.address();
269 3 : bool duplicate = false;
270 3 : for (auto const& seen : addrs)
271 : {
272 MIS 0 : if (seen == a)
273 : {
274 0 : duplicate = true;
275 0 : break;
276 : }
277 : }
278 : // The same address can come back more than once
279 : // (mixed name sources, repeated records); each
280 : // address is reported once
281 HIT 3 : if (!duplicate)
282 3 : addrs.push_back(a);
283 : }
284 12 : return {ec_, std::move(addrs)};
285 6 : }
286 : };
287 :
288 : struct reverse_resolve_awaitable
289 : : detail::value_op_base<reverse_resolve_awaitable, endpoint_name>
290 : {
291 : private:
292 : friend resolver;
293 :
294 22 : reverse_resolve_awaitable(
295 : resolver& r, endpoint const& ep, reverse_flags flags) noexcept
296 44 : : r_(r)
297 22 : , ep_(ep)
298 22 : , flags_(flags)
299 : {
300 22 : }
301 :
302 : friend detail::value_op_base<reverse_resolve_awaitable, endpoint_name>;
303 :
304 : resolver& r_;
305 : endpoint ep_;
306 : reverse_flags flags_;
307 :
308 : std::coroutine_handle<>
309 21 : dispatch(capy::continuation& cont, capy::executor_ref ex) const
310 : {
311 42 : return r_.get().reverse_resolve(
312 42 : cont, ex, ep_, flags_, token_, &ec_, &value_);
313 : }
314 : };
315 :
316 : public:
317 : /** Destructor.
318 :
319 : Cancels any pending operations.
320 : */
321 : ~resolver() override;
322 :
323 : /** Construct a resolver from an execution context.
324 :
325 : @param ctx The execution context that owns this resolver.
326 : */
327 : explicit resolver(capy::execution_context& ctx);
328 :
329 : /** Construct a resolver from an executor.
330 :
331 : The resolver is associated with the executor's context.
332 :
333 : @param ex The executor whose context owns the resolver.
334 : */
335 : template<class Ex>
336 : requires(!std::same_as<std::remove_cvref_t<Ex>, resolver>) &&
337 : capy::Executor<Ex>
338 1 : explicit resolver(Ex const& ex) : resolver(ex.context())
339 : {
340 1 : }
341 :
342 : /** Move constructor.
343 :
344 : Transfers ownership of the resolver resources. After the move,
345 : @p other is in a moved-from state and may only be destroyed or
346 : assigned to.
347 :
348 : @param other The resolver to move from.
349 :
350 : @pre No awaitables returned by @p other's `resolve` methods
351 : exist.
352 : @pre The execution context associated with @p other must
353 : outlive this resolver.
354 : */
355 10 : resolver(resolver&& other) noexcept : io_object(std::move(other)) {}
356 :
357 : /** Move assignment operator.
358 :
359 : Destroys the current implementation and transfers ownership
360 : from @p other. After the move, @p other is in a moved-from
361 : state and may only be destroyed or assigned to.
362 :
363 : @param other The resolver to move from.
364 :
365 : @pre No awaitables returned by either `*this` or @p other's
366 : `resolve` methods exist.
367 : @pre The execution context associated with @p other must
368 : outlive this resolver.
369 :
370 : @return Reference to this resolver.
371 : */
372 2 : resolver& operator=(resolver&& other) noexcept
373 : {
374 2 : if (this != &other)
375 2 : h_ = std::move(other.h_);
376 2 : return *this;
377 : }
378 :
379 : /// Copy construction is disabled; the handle is uniquely owned.
380 : resolver(resolver const&) = delete;
381 : /// Copy assignment is disabled; the handle is uniquely owned.
382 : resolver& operator=(resolver const&) = delete;
383 :
384 : /** Initiate an asynchronous resolve operation.
385 :
386 : Resolves the host and service names into a list of endpoints.
387 :
388 : This resolver must outlive the returned awaitable.
389 :
390 : @param host A string identifying a location. May be a descriptive
391 : name or a numeric address string.
392 :
393 : @param service A string identifying the requested service. This may
394 : be a descriptive name or a numeric string corresponding to a
395 : port number.
396 :
397 : @return An awaitable that completes with
398 : `results<std::vector<endpoint>>`.
399 :
400 : @par Example
401 : @par !example forward_resolve
402 : */
403 15 : [[nodiscard]] auto resolve(std::string_view host, std::string_view service)
404 : {
405 15 : return resolve_awaitable(*this, host, service, resolve_flags::none);
406 : }
407 :
408 : /** Initiate an asynchronous host-only resolve operation.
409 :
410 : Resolves a host name into its addresses, with no service or
411 : port involved — the query `getaddrinfo` performs with a null
412 : service. Use this when the host and port travel separately,
413 : as they do in most configuration.
414 :
415 : Each address appears once in the result even when the query
416 : reports it more than once, and link-local results keep
417 : their zone.
418 :
419 : @param host The host name or numeric address string.
420 :
421 : @return An awaitable that completes with
422 : `results<std::vector<ip_address>>`.
423 :
424 : @par Example
425 : @par !example host_only_resolve
426 : */
427 3 : [[nodiscard]] auto resolve(std::string_view host)
428 : {
429 3 : return resolve_host_awaitable(*this, host, resolve_flags::none);
430 : }
431 :
432 : /** Initiate an asynchronous host-only resolve operation with flags.
433 :
434 : @param host The host name or numeric address string.
435 : @param flags Resolution behavior flags.
436 :
437 : @return An awaitable that completes with
438 : `results<std::vector<ip_address>>`.
439 : */
440 3 : [[nodiscard]] auto resolve(std::string_view host, resolve_flags flags)
441 : {
442 3 : return resolve_host_awaitable(*this, host, flags);
443 : }
444 :
445 : /** Initiate an asynchronous resolve operation with flags.
446 :
447 : Resolves the host and service names into a list of endpoints.
448 :
449 : This resolver must outlive the returned awaitable.
450 :
451 : @param host A string identifying a location.
452 :
453 : @param service A string identifying the requested service.
454 :
455 : @param flags Flags controlling resolution behavior.
456 :
457 : @return An awaitable that completes with
458 : `results<std::vector<endpoint>>`.
459 : */
460 22 : [[nodiscard]] auto resolve(
461 : std::string_view host, std::string_view service, resolve_flags flags)
462 : {
463 22 : return resolve_awaitable(*this, host, service, flags);
464 : }
465 :
466 : /** Initiate an asynchronous reverse resolve operation.
467 :
468 : Resolves an endpoint into a hostname and service name using
469 : reverse DNS lookup (PTR record query).
470 :
471 : This resolver must outlive the returned awaitable.
472 :
473 : @param ep The endpoint to resolve.
474 :
475 : @return An awaitable that completes with
476 : `results<endpoint_name>`.
477 :
478 : @par Example
479 : @par !example reverse_resolve
480 : */
481 11 : [[nodiscard]] auto resolve(endpoint const& ep)
482 : {
483 11 : return reverse_resolve_awaitable(*this, ep, reverse_flags::none);
484 : }
485 :
486 : /** Initiate an asynchronous reverse resolve operation with flags.
487 :
488 : Resolves an endpoint into a hostname and service name using
489 : reverse DNS lookup (PTR record query).
490 :
491 : This resolver must outlive the returned awaitable.
492 :
493 : @param ep The endpoint to resolve.
494 :
495 : @param flags Flags controlling resolution behavior. See reverse_flags.
496 :
497 : @return An awaitable that completes with
498 : `results<endpoint_name>`.
499 : */
500 11 : [[nodiscard]] auto resolve(endpoint const& ep, reverse_flags flags)
501 : {
502 11 : return reverse_resolve_awaitable(*this, ep, flags);
503 : }
504 :
505 : /** Cancel any pending asynchronous operations.
506 :
507 : A resolve transfers no bytes, so a cancellation always wins. An
508 : operation reports `errc::operation_canceled` even when the lookup
509 : had already completed when the cancellation landed. Check
510 : `ec == cond::canceled` for a portable comparison.
511 : */
512 : void cancel() noexcept;
513 :
514 : public:
515 : /** Define backend hooks for DNS resolution operations.
516 :
517 : Platform backends derive from this to implement forward and
518 : reverse DNS resolution via `getaddrinfo`/`getnameinfo`.
519 : */
520 : struct implementation : io_object::implementation
521 : {
522 : /** Initiate an asynchronous forward DNS resolution.
523 :
524 : @param cont Continuation to resume on completion; it lives in
525 : the awaiting frame until then.
526 : @param ex Executor for dispatching the completion.
527 : @param host The host name or address literal to resolve.
528 : @param service The service name or port number.
529 : @param flags Flags controlling the lookup.
530 : @param token Stop token for cancellation.
531 : @param ec Output error code.
532 : @param results Output resolver results.
533 :
534 : @return Coroutine handle to resume immediately.
535 : */
536 : virtual std::coroutine_handle<> resolve(
537 : capy::continuation& cont,
538 : capy::executor_ref ex,
539 : std::string_view host,
540 : std::string_view service,
541 : resolve_flags flags,
542 : std::stop_token token,
543 : std::error_code* ec,
544 : std::vector<endpoint>* results) = 0;
545 :
546 : /** Initiate an asynchronous reverse DNS resolution.
547 :
548 : @param cont Continuation to resume on completion; it lives in
549 : the awaiting frame until then.
550 : @param ex Executor for dispatching the completion.
551 : @param ep The endpoint to resolve.
552 : @param flags Flags controlling the lookup.
553 : @param token Stop token for cancellation.
554 : @param ec Output error code.
555 : @param result Output reverse-resolution result.
556 :
557 : @return Coroutine handle to resume immediately.
558 : */
559 : virtual std::coroutine_handle<> reverse_resolve(
560 : capy::continuation& cont,
561 : capy::executor_ref ex,
562 : endpoint const& ep,
563 : reverse_flags flags,
564 : std::stop_token token,
565 : std::error_code* ec,
566 : endpoint_name* result) = 0;
567 :
568 : /// Cancel pending resolve operations.
569 : virtual void cancel() noexcept = 0;
570 : };
571 :
572 : protected:
573 : /** Adopt an existing handle.
574 :
575 : @param h The handle the resolver takes ownership of.
576 : */
577 : explicit resolver(handle h) noexcept : io_object(std::move(h)) {}
578 :
579 : private:
580 69 : inline implementation& get() const noexcept
581 : {
582 69 : return *static_cast<implementation*>(h_.get());
583 : }
584 : };
585 :
586 : } // namespace boost::corosio
587 :
588 : #endif
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