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/corosio/resolver_results.hpp>
21 : #include <boost/capy/ex/executor_ref.hpp>
22 : #include <boost/capy/ex/execution_context.hpp>
23 : #include <boost/capy/ex/io_env.hpp>
24 : #include <boost/capy/concept/executor.hpp>
25 :
26 : #include <system_error>
27 :
28 : #include <cassert>
29 : #include <concepts>
30 : #include <coroutine>
31 : #include <stop_token>
32 : #include <string>
33 : #include <string_view>
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
90 199 : operator&(resolve_flags a, resolve_flags b) noexcept
91 : {
92 : return static_cast<resolve_flags>(
93 199 : 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 79 : operator&(reverse_flags a, reverse_flags b) noexcept
145 : {
146 : return static_cast<reverse_flags>(
147 79 : 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 : /** An asynchronous DNS resolver for coroutine I/O.
159 :
160 : This class provides asynchronous DNS resolution operations that return
161 : awaitable types. Each operation participates in the affine awaitable
162 : protocol, ensuring coroutines resume on the correct executor.
163 :
164 : @par Thread Safety
165 : Distinct objects: Safe.@n
166 : Shared objects: Unsafe. A resolver must not have concurrent resolve
167 : operations.
168 :
169 : @par Semantics
170 : Wraps platform DNS resolution (getaddrinfo/getnameinfo).
171 : Operations dispatch to OS resolver APIs via the io_context
172 : thread pool.
173 :
174 : @par Example
175 : @code
176 : io_context ioc;
177 : resolver r(ioc);
178 :
179 : // Using structured bindings
180 : auto [ec, results] = co_await r.resolve("www.example.com", "https");
181 : if (ec)
182 : co_return;
183 :
184 : for (auto const& entry : results)
185 : std::cout << entry.get_endpoint().port() << std::endl;
186 :
187 : // Or, to convert errors into exceptions:
188 : auto [ec2, results2] = co_await r.resolve("www.example.com", "https");
189 : if (ec2)
190 : throw std::system_error(ec2);
191 : @endcode
192 : */
193 : class BOOST_COROSIO_DECL resolver : public io_object
194 : {
195 : struct resolve_awaitable
196 : : detail::value_op_base<resolve_awaitable, resolver_results>
197 : {
198 : resolver& r_;
199 : std::string host_;
200 : std::string service_;
201 : resolve_flags flags_;
202 :
203 30 : resolve_awaitable(
204 : resolver& r,
205 : std::string_view host,
206 : std::string_view service,
207 : resolve_flags flags) noexcept
208 60 : : r_(r)
209 60 : , host_(host)
210 60 : , service_(service)
211 30 : , flags_(flags)
212 : {
213 30 : }
214 :
215 30 : std::coroutine_handle<> dispatch(
216 : std::coroutine_handle<> h, capy::executor_ref ex) const
217 : {
218 90 : return r_.get().resolve(
219 90 : h, ex, host_, service_, flags_, token_, &ec_, &value_);
220 : }
221 : };
222 :
223 : struct reverse_resolve_awaitable
224 : : detail::value_op_base<reverse_resolve_awaitable, reverse_resolver_result>
225 : {
226 : resolver& r_;
227 : endpoint ep_;
228 : reverse_flags flags_;
229 :
230 20 : reverse_resolve_awaitable(
231 : resolver& r, endpoint const& ep, reverse_flags flags) noexcept
232 40 : : r_(r)
233 20 : , ep_(ep)
234 20 : , flags_(flags)
235 : {
236 20 : }
237 :
238 20 : std::coroutine_handle<> dispatch(
239 : std::coroutine_handle<> h, capy::executor_ref ex) const
240 : {
241 40 : return r_.get().reverse_resolve(
242 40 : h, ex, ep_, flags_, token_, &ec_, &value_);
243 : }
244 : };
245 :
246 : public:
247 : /** Destructor.
248 :
249 : Cancels any pending operations.
250 : */
251 : ~resolver() override;
252 :
253 : /** Construct a resolver from an execution context.
254 :
255 : @param ctx The execution context that will own this resolver.
256 : */
257 : explicit resolver(capy::execution_context& ctx);
258 :
259 : /** Construct a resolver from an executor.
260 :
261 : The resolver is associated with the executor's context.
262 :
263 : @param ex The executor whose context will own the resolver.
264 : */
265 : template<class Ex>
266 : requires(!std::same_as<std::remove_cvref_t<Ex>, resolver>) &&
267 : capy::Executor<Ex>
268 1 : explicit resolver(Ex const& ex) : resolver(ex.context())
269 : {
270 1 : }
271 :
272 : /** Move constructor.
273 :
274 : Transfers ownership of the resolver resources. After the move,
275 : @p other is in a moved-from state and may only be destroyed or
276 : assigned to.
277 :
278 : @param other The resolver to move from.
279 :
280 : @pre No awaitables returned by @p other's `resolve` methods
281 : exist.
282 : @pre The execution context associated with @p other must
283 : outlive this resolver.
284 : */
285 2 : resolver(resolver&& other) noexcept : io_object(std::move(other)) {}
286 :
287 : /** Move assignment operator.
288 :
289 : Destroys the current implementation and transfers ownership
290 : from @p other. After the move, @p other is in a moved-from
291 : state and may only be destroyed or assigned to.
292 :
293 : @param other The resolver to move from.
294 :
295 : @pre No awaitables returned by either `*this` or @p other's
296 : `resolve` methods exist.
297 : @pre The execution context associated with @p other must
298 : outlive this resolver.
299 :
300 : @return Reference to this resolver.
301 : */
302 2 : resolver& operator=(resolver&& other) noexcept
303 : {
304 2 : if (this != &other)
305 2 : h_ = std::move(other.h_);
306 2 : return *this;
307 : }
308 :
309 : resolver(resolver const&) = delete;
310 : resolver& operator=(resolver const&) = delete;
311 :
312 : /** Initiate an asynchronous resolve operation.
313 :
314 : Resolves the host and service names into a list of endpoints.
315 :
316 : This resolver must outlive the returned awaitable.
317 :
318 : @param host A string identifying a location. May be a descriptive
319 : name or a numeric address string.
320 :
321 : @param service A string identifying the requested service. This may
322 : be a descriptive name or a numeric string corresponding to a
323 : port number.
324 :
325 : @return An awaitable that completes with `io_result<resolver_results>`.
326 :
327 : @note `resolver_results` is an alias for `std::vector<resolver_entry>`.
328 : Copying it deep-copies every entry (each owns two `std::string`s);
329 : move it (`std::move(results)`) or pass iterators when handing it to
330 : a by-value sink such as @ref connect.
331 :
332 : @par Example
333 : @code
334 : auto [ec, results] = co_await r.resolve("www.example.com", "https");
335 : @endcode
336 : */
337 14 : [[nodiscard]] auto resolve(std::string_view host, std::string_view service)
338 : {
339 14 : return resolve_awaitable(*this, host, service, resolve_flags::none);
340 : }
341 :
342 : /** Initiate an asynchronous resolve operation with flags.
343 :
344 : Resolves the host and service names into a list of endpoints.
345 :
346 : This resolver must outlive the returned awaitable.
347 :
348 : @param host A string identifying a location.
349 :
350 : @param service A string identifying the requested service.
351 :
352 : @param flags Flags controlling resolution behavior.
353 :
354 : @return An awaitable that completes with `io_result<resolver_results>`.
355 : */
356 16 : [[nodiscard]] auto resolve(
357 : std::string_view host, std::string_view service, resolve_flags flags)
358 : {
359 16 : return resolve_awaitable(*this, host, service, flags);
360 : }
361 :
362 : /** Initiate an asynchronous reverse resolve operation.
363 :
364 : Resolves an endpoint into a hostname and service name using
365 : reverse DNS lookup (PTR record query).
366 :
367 : This resolver must outlive the returned awaitable.
368 :
369 : @param ep The endpoint to resolve.
370 :
371 : @return An awaitable that completes with
372 : `io_result<reverse_resolver_result>`.
373 :
374 : @par Example
375 : @code
376 : endpoint ep(ipv4_address({127, 0, 0, 1}), 80);
377 : auto [ec, result] = co_await r.resolve(ep);
378 : if (!ec)
379 : std::cout << result.host_name() << ":" << result.service_name();
380 : @endcode
381 : */
382 11 : [[nodiscard]] auto resolve(endpoint const& ep)
383 : {
384 11 : return reverse_resolve_awaitable(*this, ep, reverse_flags::none);
385 : }
386 :
387 : /** Initiate an asynchronous reverse resolve operation with flags.
388 :
389 : Resolves an endpoint into a hostname and service name using
390 : reverse DNS lookup (PTR record query).
391 :
392 : This resolver must outlive the returned awaitable.
393 :
394 : @param ep The endpoint to resolve.
395 :
396 : @param flags Flags controlling resolution behavior. See reverse_flags.
397 :
398 : @return An awaitable that completes with
399 : `io_result<reverse_resolver_result>`.
400 : */
401 9 : [[nodiscard]] auto resolve(endpoint const& ep, reverse_flags flags)
402 : {
403 9 : return reverse_resolve_awaitable(*this, ep, flags);
404 : }
405 :
406 : /** Cancel any pending asynchronous operations.
407 :
408 : All outstanding operations complete with `errc::operation_canceled`.
409 : Check `ec == cond::canceled` for portable comparison.
410 : */
411 : void cancel() noexcept;
412 :
413 : public:
414 : /** Backend interface for DNS resolution operations.
415 :
416 : Platform backends derive from this to implement forward and
417 : reverse DNS resolution via getaddrinfo/getnameinfo.
418 : */
419 : struct implementation : io_object::implementation
420 : {
421 : /// Initiate an asynchronous forward DNS resolution.
422 : virtual std::coroutine_handle<> resolve(
423 : std::coroutine_handle<>,
424 : capy::executor_ref,
425 : std::string_view host,
426 : std::string_view service,
427 : resolve_flags flags,
428 : std::stop_token,
429 : std::error_code*,
430 : resolver_results*) = 0;
431 :
432 : /// Initiate an asynchronous reverse DNS resolution.
433 : virtual std::coroutine_handle<> reverse_resolve(
434 : std::coroutine_handle<>,
435 : capy::executor_ref,
436 : endpoint const& ep,
437 : reverse_flags flags,
438 : std::stop_token,
439 : std::error_code*,
440 : reverse_resolver_result*) = 0;
441 :
442 : /// Cancel pending resolve operations.
443 : virtual void cancel() noexcept = 0;
444 : };
445 :
446 : protected:
447 : explicit resolver(handle h) noexcept : io_object(std::move(h)) {}
448 :
449 : private:
450 57 : inline implementation& get() const noexcept
451 : {
452 57 : return *static_cast<implementation*>(h_.get());
453 : }
454 : };
455 :
456 : } // namespace boost::corosio
457 :
458 : #endif
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