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/*
* Copyright 2008 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.
*/
#include "rtc_base/async_resolver.h"
#include <memory>
#include <string>
#include <utility>
#include "absl/strings/string_view.h"
#include "api/ref_counted_base.h"
#include "rtc_base/synchronization/mutex.h"
#include "rtc_base/thread_annotations.h"
#if defined(WEBRTC_WIN)
#include <ws2spi.h>
#include <ws2tcpip.h>
#include "rtc_base/win32.h"
#endif
#if defined(WEBRTC_POSIX) && !defined(__native_client__)
#if defined(WEBRTC_ANDROID)
#include "rtc_base/ifaddrs_android.h"
#else
#include <ifaddrs.h>
#endif
#endif // defined(WEBRTC_POSIX) && !defined(__native_client__)
#include "api/task_queue/task_queue_base.h"
#include "rtc_base/ip_address.h"
#include "rtc_base/logging.h"
#include "rtc_base/platform_thread.h"
#include "rtc_base/task_queue.h"
#include "rtc_base/third_party/sigslot/sigslot.h" // for signal_with_thread...
#if defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
#include <dispatch/dispatch.h>
#endif
namespace rtc {
#if defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
namespace {
void GlobalGcdRunTask(void* context) {
std::unique_ptr<absl::AnyInvocable<void() &&>> task(
static_cast<absl::AnyInvocable<void() &&>*>(context));
std::move (*task)();
}
// Post a task into the system-defined global concurrent queue.
void PostTaskToGlobalQueue(
std::unique_ptr<absl::AnyInvocable<void() &&>> task) {
dispatch_queue_global_t global_queue =
dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async_f(global_queue, task.release(), &GlobalGcdRunTask);
}
} // namespace
#endif
int ResolveHostname(absl::string_view hostname,
int family,
std::vector<IPAddress>* addresses) {
#ifdef __native_client__
RTC_DCHECK_NOTREACHED();
RTC_LOG(LS_WARNING) << "ResolveHostname() is not implemented for NaCl";
return -1;
#else // __native_client__
if (!addresses) {
return -1;
}
addresses->clear();
struct addrinfo* result = nullptr;
struct addrinfo hints = {0};
hints.ai_family = family;
// `family` here will almost always be AF_UNSPEC, because `family` comes from
// AsyncResolver::addr_.family(), which comes from a SocketAddress constructed
// with a hostname. When a SocketAddress is constructed with a hostname, its
// family is AF_UNSPEC. However, if someday in the future we construct
// a SocketAddress with both a hostname and a family other than AF_UNSPEC,
// then it would be possible to get a specific family value here.
// The behavior of AF_UNSPEC is roughly "get both ipv4 and ipv6", as
// documented by the various operating systems:
// Linux: http://man7.org/linux/man-pages/man3/getaddrinfo.3.html
// Windows: https://msdn.microsoft.com/en-us/library/windows/desktop/
// ms738520(v=vs.85).aspx
// Mac: https://developer.apple.com/legacy/library/documentation/Darwin/
// Reference/ManPages/man3/getaddrinfo.3.html
// Android (source code, not documentation):
// https://android.googlesource.com/platform/bionic/+/
// 7e0bfb511e85834d7c6cb9631206b62f82701d60/libc/netbsd/net/getaddrinfo.c#1657
hints.ai_flags = AI_ADDRCONFIG;
int ret =
getaddrinfo(std::string(hostname).c_str(), nullptr, &hints, &result);
if (ret != 0) {
return ret;
}
struct addrinfo* cursor = result;
for (; cursor; cursor = cursor->ai_next) {
if (family == AF_UNSPEC || cursor->ai_family == family) {
IPAddress ip;
if (IPFromAddrInfo(cursor, &ip)) {
addresses->push_back(ip);
}
}
}
freeaddrinfo(result);
return 0;
#endif // !__native_client__
}
struct AsyncResolver::State : public RefCountedBase {
webrtc::Mutex mutex;
enum class Status {
kLive,
kDead
} status RTC_GUARDED_BY(mutex) = Status::kLive;
};
AsyncResolver::AsyncResolver() : error_(-1), state_(new State) {}
AsyncResolver::~AsyncResolver() {
RTC_DCHECK_RUN_ON(&sequence_checker_);
// Ensure the thread isn't using a stale reference to the current task queue,
// or calling into ResolveDone post destruction.
webrtc::MutexLock lock(&state_->mutex);
state_->status = State::Status::kDead;
}
void RunResolution(void* obj) {
std::function<void()>* function_ptr =
static_cast<std::function<void()>*>(obj);
(*function_ptr)();
delete function_ptr;
}
void AsyncResolver::Start(const SocketAddress& addr) {
Start(addr, addr.family());
}
void AsyncResolver::Start(const SocketAddress& addr, int family) {
RTC_DCHECK_RUN_ON(&sequence_checker_);
RTC_DCHECK(!destroy_called_);
addr_ = addr;
auto thread_function =
[this, addr, family, caller_task_queue = webrtc::TaskQueueBase::Current(),
state = state_] {
std::vector<IPAddress> addresses;
int error = ResolveHostname(addr.hostname(), family, &addresses);
webrtc::MutexLock lock(&state->mutex);
if (state->status == State::Status::kLive) {
caller_task_queue->PostTask(
[this, error, addresses = std::move(addresses), state] {
bool live;
{
// ResolveDone can lead to instance destruction, so make sure
// we don't deadlock.
webrtc::MutexLock lock(&state->mutex);
live = state->status == State::Status::kLive;
}
if (live) {
RTC_DCHECK_RUN_ON(&sequence_checker_);
ResolveDone(std::move(addresses), error);
}
});
}
};
#if defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
PostTaskToGlobalQueue(
std::make_unique<absl::AnyInvocable<void() &&>>(thread_function));
#else
PlatformThread::SpawnDetached(std::move(thread_function), "AsyncResolver");
#endif
}
bool AsyncResolver::GetResolvedAddress(int family, SocketAddress* addr) const {
RTC_DCHECK_RUN_ON(&sequence_checker_);
RTC_DCHECK(!destroy_called_);
if (error_ != 0 || addresses_.empty())
return false;
*addr = addr_;
for (size_t i = 0; i < addresses_.size(); ++i) {
if (family == addresses_[i].family()) {
addr->SetResolvedIP(addresses_[i]);
return true;
}
}
return false;
}
int AsyncResolver::GetError() const {
RTC_DCHECK_RUN_ON(&sequence_checker_);
RTC_DCHECK(!destroy_called_);
return error_;
}
void AsyncResolver::Destroy(bool wait) {
// Some callers have trouble guaranteeing that Destroy is called on the
// sequence guarded by `sequence_checker_`.
// RTC_DCHECK_RUN_ON(&sequence_checker_);
RTC_DCHECK(!destroy_called_);
destroy_called_ = true;
MaybeSelfDestruct();
}
const std::vector<IPAddress>& AsyncResolver::addresses() const {
RTC_DCHECK_RUN_ON(&sequence_checker_);
RTC_DCHECK(!destroy_called_);
return addresses_;
}
void AsyncResolver::ResolveDone(std::vector<IPAddress> addresses, int error) {
addresses_ = addresses;
error_ = error;
recursion_check_ = true;
SignalDone(this);
MaybeSelfDestruct();
}
void AsyncResolver::MaybeSelfDestruct() {
if (!recursion_check_) {
delete this;
} else {
recursion_check_ = false;
}
}
} // namespace rtc
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