TLA Line data Source code
1 : //
2 : // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3 : // Copyright (c) 2026 Steve Gerbino
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_RESOLVER_HPP
12 : #define BOOST_COROSIO_RESOLVER_HPP
13 :
14 : #include <boost/corosio/detail/config.hpp>
15 : #include <boost/corosio/endpoint.hpp>
16 : #include <boost/corosio/io/io_object.hpp>
17 : #include <boost/capy/io_result.hpp>
18 : #include <boost/corosio/resolver_results.hpp>
19 : #include <boost/capy/ex/executor_ref.hpp>
20 : #include <boost/capy/ex/execution_context.hpp>
21 : #include <boost/capy/ex/io_env.hpp>
22 : #include <boost/capy/concept/executor.hpp>
23 :
24 : #include <system_error>
25 :
26 : #include <cassert>
27 : #include <concepts>
28 : #include <coroutine>
29 : #include <stop_token>
30 : #include <string>
31 : #include <string_view>
32 : #include <type_traits>
33 :
34 : namespace boost::corosio {
35 :
36 : /** Bitmask flags for resolver queries.
37 :
38 : These flags correspond to the hints parameter of getaddrinfo.
39 : */
40 : enum class resolve_flags : unsigned int
41 : {
42 : /// No flags.
43 : none = 0,
44 :
45 : /// Indicate that returned endpoint is intended for use as a locally
46 : /// bound socket endpoint.
47 : passive = 0x01,
48 :
49 : /// Host name should be treated as a numeric string defining an IPv4
50 : /// or IPv6 address and no name resolution should be attempted.
51 : numeric_host = 0x04,
52 :
53 : /// Service name should be treated as a numeric string defining a port
54 : /// number and no name resolution should be attempted.
55 : numeric_service = 0x08,
56 :
57 : /// Only return IPv4 addresses if a non-loopback IPv4 address is
58 : /// configured for the system. Only return IPv6 addresses if a
59 : /// non-loopback IPv6 address is configured for the system.
60 : address_configured = 0x20,
61 :
62 : /// If the query protocol family is specified as IPv6, return
63 : /// IPv4-mapped IPv6 addresses on finding no IPv6 addresses.
64 : v4_mapped = 0x800,
65 :
66 : /// If used with v4_mapped, return all matching IPv6 and IPv4 addresses.
67 : all_matching = 0x100
68 : };
69 :
70 : /** Combine two resolve_flags. */
71 : inline resolve_flags
72 HIT 10 : operator|(resolve_flags a, resolve_flags b) noexcept
73 : {
74 : return static_cast<resolve_flags>(
75 10 : static_cast<unsigned int>(a) | static_cast<unsigned int>(b));
76 : }
77 :
78 : /** Combine two resolve_flags. */
79 : inline resolve_flags&
80 1 : operator|=(resolve_flags& a, resolve_flags b) noexcept
81 : {
82 1 : a = a | b;
83 1 : return a;
84 : }
85 :
86 : /** Intersect two resolve_flags. */
87 : inline resolve_flags
88 103 : operator&(resolve_flags a, resolve_flags b) noexcept
89 : {
90 : return static_cast<resolve_flags>(
91 103 : static_cast<unsigned int>(a) & static_cast<unsigned int>(b));
92 : }
93 :
94 : /** Intersect two resolve_flags. */
95 : inline resolve_flags&
96 1 : operator&=(resolve_flags& a, resolve_flags b) noexcept
97 : {
98 1 : a = a & b;
99 1 : return a;
100 : }
101 :
102 : /** Bitmask flags for reverse resolver queries.
103 :
104 : These flags correspond to the flags parameter of getnameinfo.
105 : */
106 : enum class reverse_flags : unsigned int
107 : {
108 : /// No flags.
109 : none = 0,
110 :
111 : /// Return the numeric form of the hostname instead of its name.
112 : numeric_host = 0x01,
113 :
114 : /// Return the numeric form of the service name instead of its name.
115 : numeric_service = 0x02,
116 :
117 : /// Return an error if the hostname cannot be resolved.
118 : name_required = 0x04,
119 :
120 : /// Lookup for datagram (UDP) service instead of stream (TCP).
121 : datagram_service = 0x08
122 : };
123 :
124 : /** Combine two reverse_flags. */
125 : inline reverse_flags
126 6 : operator|(reverse_flags a, reverse_flags b) noexcept
127 : {
128 : return static_cast<reverse_flags>(
129 6 : static_cast<unsigned int>(a) | static_cast<unsigned int>(b));
130 : }
131 :
132 : /** Combine two reverse_flags. */
133 : inline reverse_flags&
134 1 : operator|=(reverse_flags& a, reverse_flags b) noexcept
135 : {
136 1 : a = a | b;
137 1 : return a;
138 : }
139 :
140 : /** Intersect two reverse_flags. */
141 : inline reverse_flags
142 47 : operator&(reverse_flags a, reverse_flags b) noexcept
143 : {
144 : return static_cast<reverse_flags>(
145 47 : static_cast<unsigned int>(a) & static_cast<unsigned int>(b));
146 : }
147 :
148 : /** Intersect two reverse_flags. */
149 : inline reverse_flags&
150 1 : operator&=(reverse_flags& a, reverse_flags b) noexcept
151 : {
152 1 : a = a & b;
153 1 : return a;
154 : }
155 :
156 : /** An asynchronous DNS resolver for coroutine I/O.
157 :
158 : This class provides asynchronous DNS resolution operations that return
159 : awaitable types. Each operation participates in the affine awaitable
160 : protocol, ensuring coroutines resume on the correct executor.
161 :
162 : @par Thread Safety
163 : Distinct objects: Safe.@n
164 : Shared objects: Unsafe. A resolver must not have concurrent resolve
165 : operations.
166 :
167 : @par Semantics
168 : Wraps platform DNS resolution (getaddrinfo/getnameinfo).
169 : Operations dispatch to OS resolver APIs via the io_context
170 : thread pool.
171 :
172 : @par Example
173 : @code
174 : io_context ioc;
175 : resolver r(ioc);
176 :
177 : // Using structured bindings
178 : auto [ec, results] = co_await r.resolve("www.example.com", "https");
179 : if (ec)
180 : co_return;
181 :
182 : for (auto const& entry : results)
183 : std::cout << entry.get_endpoint().port() << std::endl;
184 :
185 : // Or using exceptions
186 : auto results = (co_await r.resolve("www.example.com", "https")).value();
187 : @endcode
188 : */
189 : class BOOST_COROSIO_DECL resolver : public io_object
190 : {
191 : struct resolve_awaitable
192 : {
193 : resolver& r_;
194 : std::string host_;
195 : std::string service_;
196 : resolve_flags flags_;
197 : std::stop_token token_;
198 : mutable std::error_code ec_;
199 : mutable resolver_results results_;
200 :
201 16 : resolve_awaitable(
202 : resolver& r,
203 : std::string_view host,
204 : std::string_view service,
205 : resolve_flags flags) noexcept
206 16 : : r_(r)
207 32 : , host_(host)
208 32 : , service_(service)
209 16 : , flags_(flags)
210 : {
211 16 : }
212 :
213 16 : bool await_ready() const noexcept
214 : {
215 16 : return token_.stop_requested();
216 : }
217 :
218 16 : capy::io_result<resolver_results> await_resume() const noexcept
219 : {
220 16 : if (token_.stop_requested())
221 MIS 0 : return {make_error_code(std::errc::operation_canceled), {}};
222 HIT 16 : return {ec_, std::move(results_)};
223 16 : }
224 :
225 16 : auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
226 : -> std::coroutine_handle<>
227 : {
228 16 : token_ = env->stop_token;
229 48 : return r_.get().resolve(
230 16 : h, env->executor, host_, service_, flags_, token_, &ec_,
231 32 : &results_);
232 : }
233 : };
234 :
235 : struct reverse_resolve_awaitable
236 : {
237 : resolver& r_;
238 : endpoint ep_;
239 : reverse_flags flags_;
240 : std::stop_token token_;
241 : mutable std::error_code ec_;
242 : mutable reverse_resolver_result result_;
243 :
244 10 : reverse_resolve_awaitable(
245 : resolver& r, endpoint const& ep, reverse_flags flags) noexcept
246 10 : : r_(r)
247 10 : , ep_(ep)
248 10 : , flags_(flags)
249 : {
250 10 : }
251 :
252 10 : bool await_ready() const noexcept
253 : {
254 10 : return token_.stop_requested();
255 : }
256 :
257 10 : capy::io_result<reverse_resolver_result> await_resume() const noexcept
258 : {
259 10 : if (token_.stop_requested())
260 MIS 0 : return {make_error_code(std::errc::operation_canceled), {}};
261 HIT 10 : return {ec_, std::move(result_)};
262 10 : }
263 :
264 10 : auto await_suspend(std::coroutine_handle<> h, capy::io_env const* env)
265 : -> std::coroutine_handle<>
266 : {
267 10 : token_ = env->stop_token;
268 20 : return r_.get().reverse_resolve(
269 20 : h, env->executor, ep_, flags_, token_, &ec_, &result_);
270 : }
271 : };
272 :
273 : public:
274 : /** Destructor.
275 :
276 : Cancels any pending operations.
277 : */
278 : ~resolver() override;
279 :
280 : /** Construct a resolver from an execution context.
281 :
282 : @param ctx The execution context that will own this resolver.
283 : */
284 : explicit resolver(capy::execution_context& ctx);
285 :
286 : /** Construct a resolver from an executor.
287 :
288 : The resolver is associated with the executor's context.
289 :
290 : @param ex The executor whose context will own the resolver.
291 : */
292 : template<class Ex>
293 : requires(!std::same_as<std::remove_cvref_t<Ex>, resolver>) &&
294 : capy::Executor<Ex>
295 1 : explicit resolver(Ex const& ex) : resolver(ex.context())
296 : {
297 1 : }
298 :
299 : /** Move constructor.
300 :
301 : Transfers ownership of the resolver resources.
302 :
303 : @param other The resolver to move from.
304 : */
305 1 : resolver(resolver&& other) noexcept : io_object(std::move(other)) {}
306 :
307 : /** Move assignment operator.
308 :
309 : Cancels any existing operations and transfers ownership.
310 : The source and destination must share the same execution context.
311 :
312 : @param other The resolver to move from.
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 : @param host A string identifying a location. May be a descriptive
331 : name or a numeric address string.
332 :
333 : @param service A string identifying the requested service. This may
334 : be a descriptive name or a numeric string corresponding to a
335 : port number.
336 :
337 : @return An awaitable that completes with `io_result<resolver_results>`.
338 :
339 : @par Example
340 : @code
341 : auto [ec, results] = co_await r.resolve("www.example.com", "https");
342 : @endcode
343 : */
344 5 : auto resolve(std::string_view host, std::string_view service)
345 : {
346 5 : return resolve_awaitable(*this, host, service, resolve_flags::none);
347 : }
348 :
349 : /** Initiate an asynchronous resolve operation with flags.
350 :
351 : Resolves the host and service names into a list of endpoints.
352 :
353 : @param host A string identifying a location.
354 :
355 : @param service A string identifying the requested service.
356 :
357 : @param flags Flags controlling resolution behavior.
358 :
359 : @return An awaitable that completes with `io_result<resolver_results>`.
360 : */
361 11 : auto resolve(
362 : std::string_view host, std::string_view service, resolve_flags flags)
363 : {
364 11 : return resolve_awaitable(*this, host, service, flags);
365 : }
366 :
367 : /** Initiate an asynchronous reverse resolve operation.
368 :
369 : Resolves an endpoint into a hostname and service name using
370 : reverse DNS lookup (PTR record query).
371 :
372 : @param ep The endpoint to resolve.
373 :
374 : @return An awaitable that completes with
375 : `io_result<reverse_resolver_result>`.
376 :
377 : @par Example
378 : @code
379 : endpoint ep(ipv4_address({127, 0, 0, 1}), 80);
380 : auto [ec, result] = co_await r.resolve(ep);
381 : if (!ec)
382 : std::cout << result.host_name() << ":" << result.service_name();
383 : @endcode
384 : */
385 3 : auto resolve(endpoint const& ep)
386 : {
387 3 : return reverse_resolve_awaitable(*this, ep, reverse_flags::none);
388 : }
389 :
390 : /** Initiate an asynchronous reverse resolve operation with flags.
391 :
392 : Resolves an endpoint into a hostname and service name using
393 : reverse DNS lookup (PTR record query).
394 :
395 : @param ep The endpoint to resolve.
396 :
397 : @param flags Flags controlling resolution behavior. See reverse_flags.
398 :
399 : @return An awaitable that completes with
400 : `io_result<reverse_resolver_result>`.
401 : */
402 7 : auto resolve(endpoint const& ep, reverse_flags flags)
403 : {
404 7 : return reverse_resolve_awaitable(*this, ep, flags);
405 : }
406 :
407 : /** Cancel any pending asynchronous operations.
408 :
409 : All outstanding operations complete with `errc::operation_canceled`.
410 : Check `ec == cond::canceled` for portable comparison.
411 : */
412 : void cancel();
413 :
414 : public:
415 : struct implementation : io_object::implementation
416 : {
417 : virtual std::coroutine_handle<> resolve(
418 : std::coroutine_handle<>,
419 : capy::executor_ref,
420 : std::string_view host,
421 : std::string_view service,
422 : resolve_flags flags,
423 : std::stop_token,
424 : std::error_code*,
425 : resolver_results*) = 0;
426 :
427 : virtual std::coroutine_handle<> reverse_resolve(
428 : std::coroutine_handle<>,
429 : capy::executor_ref,
430 : endpoint const& ep,
431 : reverse_flags flags,
432 : std::stop_token,
433 : std::error_code*,
434 : reverse_resolver_result*) = 0;
435 :
436 : virtual void cancel() noexcept = 0;
437 : };
438 :
439 : protected:
440 : explicit resolver(handle h) noexcept : io_object(std::move(h)) {}
441 :
442 : private:
443 30 : inline implementation& get() const noexcept
444 : {
445 30 : return *static_cast<implementation*>(h_.get());
446 : }
447 : };
448 :
449 : } // namespace boost::corosio
450 :
451 : #endif
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