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/*
* Copyright 2021 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef API_ASYNC_DNS_RESOLVER_H_
#define API_ASYNC_DNS_RESOLVER_H_
#include <memory>
#include "absl/functional/any_invocable.h"
#include "rtc_base/socket_address.h"
#include "rtc_base/system/rtc_export.h"
namespace webrtc {
// This interface defines the methods to resolve a hostname asynchronously.
// The AsyncDnsResolverInterface class encapsulates a single name query.
//
// Usage:
// std::unique_ptr<AsyncDnsResolverInterface> resolver =
// factory->Create(address-to-be-resolved, [r = resolver.get()]() {
// if (r->result.GetResolvedAddress(AF_INET, &addr) {
// // success
// } else {
// // failure
// error = r->result().GetError();
// }
// // Release resolver.
// resolver_list.erase(std::remove_if(resolver_list.begin(),
// resolver_list.end(),
// [](refptr) { refptr.get() == r; });
// });
// resolver_list.push_back(std::move(resolver));
class AsyncDnsResolverResult {
public:
virtual ~AsyncDnsResolverResult() = default;
// Returns true iff the address from `Start` was successfully resolved.
// If the address was successfully resolved, sets `addr` to a copy of the
// address from `Start` with the IP address set to the top most resolved
// address of `family` (`addr` will have both hostname and the resolved ip).
virtual bool GetResolvedAddress(int family, SocketAddress* addr) const = 0;
// Returns error from resolver.
virtual int GetError() const = 0;
};
// The API for a single name query.
// The constructor, destructor and all functions must be called from
// the same sequence, and the callback will also be called on that sequence.
// The class guarantees that the callback will not be called if the
// resolver's destructor has been called.
class RTC_EXPORT AsyncDnsResolverInterface {
public:
virtual ~AsyncDnsResolverInterface() = default;
// Start address resolution of the hostname in `addr`.
virtual void Start(const SocketAddress& addr,
absl::AnyInvocable<void()> callback) = 0;
// Start address resolution of the hostname in `addr` matching `family`.
virtual void Start(const SocketAddress& addr,
int family,
absl::AnyInvocable<void()> callback) = 0;
virtual const AsyncDnsResolverResult& result() const = 0;
};
// An abstract factory for creating AsyncDnsResolverInterfaces. This allows
// client applications to provide WebRTC with their own mechanism for
// performing DNS resolution.
class AsyncDnsResolverFactoryInterface {
public:
virtual ~AsyncDnsResolverFactoryInterface() = default;
// Creates an AsyncDnsResolver and starts resolving the name. The callback
// will be called when resolution is finished.
// The callback will be called on the sequence that the caller runs on.
virtual std::unique_ptr<AsyncDnsResolverInterface> CreateAndResolve(
const SocketAddress& addr,
absl::AnyInvocable<void()> callback) = 0;
// Creates an AsyncDnsResolver and starts resolving the name to an address
// matching the specified family. The callback will be called when resolution
// is finished. The callback will be called on the sequence that the caller
// runs on.
virtual std::unique_ptr<AsyncDnsResolverInterface> CreateAndResolve(
const SocketAddress& addr,
int family,
absl::AnyInvocable<void()> callback) = 0;
// Creates an AsyncDnsResolver and does not start it.
// For backwards compatibility, will be deprecated and removed.
// One has to do a separate Start() call on the
// resolver to start name resolution.
virtual std::unique_ptr<AsyncDnsResolverInterface> Create() = 0;
};
} // namespace webrtc
#endif // API_ASYNC_DNS_RESOLVER_H_
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