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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_WRAPPING_ASYNC_DNS_RESOLVER_H_
#define API_WRAPPING_ASYNC_DNS_RESOLVER_H_
#include <functional>
#include <memory>
#include <utility>
#include "absl/memory/memory.h"
#include "api/async_dns_resolver.h"
#include "api/sequence_checker.h"
#include "rtc_base/async_resolver.h"
#include "rtc_base/async_resolver_interface.h"
#include "rtc_base/checks.h"
#include "rtc_base/socket_address.h"
#include "rtc_base/third_party/sigslot/sigslot.h"
#include "rtc_base/thread_annotations.h"
// This file defines a DNS resolver that wraps an old-style
// AsyncResolver.
// It is part of the conversion to the newer interface, and will go away
// once conversion is finished.
// TODO(bugs.webrtc.org/12598): Delete this API.
namespace webrtc {
class WrappingAsyncDnsResolver;
class RTC_EXPORT WrappingAsyncDnsResolverResult
: public AsyncDnsResolverResult {
public:
explicit WrappingAsyncDnsResolverResult(WrappingAsyncDnsResolver* owner)
: owner_(owner) {}
~WrappingAsyncDnsResolverResult() {}
// Note: Inline declaration not possible, since it refers to
// WrappingAsyncDnsResolver.
bool GetResolvedAddress(int family, rtc::SocketAddress* addr) const override;
int GetError() const override;
private:
WrappingAsyncDnsResolver* const owner_;
};
class RTC_EXPORT WrappingAsyncDnsResolver : public AsyncDnsResolverInterface,
public sigslot::has_slots<> {
public:
explicit WrappingAsyncDnsResolver(rtc::AsyncResolverInterface* wrapped)
: wrapped_(absl::WrapUnique(wrapped)), result_(this) {}
~WrappingAsyncDnsResolver() override {
// Workaround to get around the fact that sigslot-using objects can't be
// destroyed from within their callback: Alert class users early.
// TODO(bugs.webrtc.org/12651): Delete this class once the sigslot users are
// gone.
RTC_CHECK(!within_resolve_result_);
wrapped_.release()->Destroy(false);
}
void Start(const rtc::SocketAddress& addr,
std::function<void()> callback) override {
RTC_DCHECK_RUN_ON(&sequence_checker_);
PrepareToResolve(std::move(callback));
wrapped_->Start(addr);
}
void Start(const rtc::SocketAddress& addr,
int family,
std::function<void()> callback) override {
RTC_DCHECK_RUN_ON(&sequence_checker_);
PrepareToResolve(std::move(callback));
wrapped_->Start(addr, family);
}
const AsyncDnsResolverResult& result() const override {
RTC_DCHECK_RUN_ON(&sequence_checker_);
RTC_DCHECK_EQ(State::kResolved, state_);
return result_;
}
private:
enum class State { kNotStarted, kStarted, kResolved };
friend class WrappingAsyncDnsResolverResult;
// For use by WrappingAsyncDnsResolverResult
rtc::AsyncResolverInterface* wrapped() const {
RTC_DCHECK_RUN_ON(&sequence_checker_);
return wrapped_.get();
}
void PrepareToResolve(std::function<void()> callback) {
RTC_DCHECK_RUN_ON(&sequence_checker_);
RTC_DCHECK_EQ(State::kNotStarted, state_);
state_ = State::kStarted;
callback_ = std::move(callback);
wrapped_->SignalDone.connect(this,
&WrappingAsyncDnsResolver::OnResolveResult);
}
void OnResolveResult(rtc::AsyncResolverInterface* ref) {
RTC_DCHECK_RUN_ON(&sequence_checker_);
RTC_DCHECK(state_ == State::kStarted);
RTC_DCHECK_EQ(ref, wrapped_.get());
state_ = State::kResolved;
within_resolve_result_ = true;
callback_();
within_resolve_result_ = false;
}
// The class variables need to be accessed on a single thread.
SequenceChecker sequence_checker_;
std::function<void()> callback_ RTC_GUARDED_BY(sequence_checker_);
std::unique_ptr<rtc::AsyncResolverInterface> wrapped_
RTC_GUARDED_BY(sequence_checker_);
State state_ RTC_GUARDED_BY(sequence_checker_) = State::kNotStarted;
WrappingAsyncDnsResolverResult result_ RTC_GUARDED_BY(sequence_checker_);
bool within_resolve_result_ RTC_GUARDED_BY(sequence_checker_) = false;
};
} // namespace webrtc
#endif // API_WRAPPING_ASYNC_DNS_RESOLVER_H_
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