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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/nqe/socket_watcher.h"
#include "base/functional/bind.h"
#include "base/location.h"
#include "base/task/single_thread_task_runner.h"
#include "base/time/tick_clock.h"
#include "base/time/time.h"
#include "net/base/ip_address.h"
namespace net::nqe::internal {
namespace {
// Generate a compact representation for |ip_addr|. For IPv4, all 32 bits
// are used and for IPv6, the first 64 bits are used as the remote host
// identifier.
std::optional<IPHash> CalculateIPHash(const IPAddress& ip_addr) {
IPAddressBytes bytes = ip_addr.bytes();
// For IPv4, the first four bytes are taken. For IPv6, the first 8 bytes are
// taken. For IPv4MappedIPv6, the last 4 bytes are taken.
int index_min = ip_addr.IsIPv4MappedIPv6() ? 12 : 0;
int index_max;
if (ip_addr.IsIPv4MappedIPv6())
index_max = 16;
else
index_max = ip_addr.IsIPv4() ? 4 : 8;
DCHECK_LE(index_min, index_max);
DCHECK_GE(8, index_max - index_min);
uint64_t result = 0ULL;
for (int i = index_min; i < index_max; ++i) {
result = result << 8;
result |= bytes[i];
}
return result;
}
} // namespace
SocketWatcher::SocketWatcher(
SocketPerformanceWatcherFactory::Protocol protocol,
const IPAddress& address,
base::TimeDelta min_notification_interval,
bool allow_rtt_private_address,
scoped_refptr<base::SingleThreadTaskRunner> task_runner,
OnUpdatedRTTAvailableCallback updated_rtt_observation_callback,
ShouldNotifyRTTCallback should_notify_rtt_callback,
const base::TickClock* tick_clock)
: protocol_(protocol),
task_runner_(std::move(task_runner)),
updated_rtt_observation_callback_(updated_rtt_observation_callback),
should_notify_rtt_callback_(should_notify_rtt_callback),
rtt_notifications_minimum_interval_(min_notification_interval),
allow_rtt_private_address_(allow_rtt_private_address),
run_rtt_callback_(allow_rtt_private_address ||
address.IsPubliclyRoutable()),
tick_clock_(tick_clock),
host_(CalculateIPHash(address)) {
DCHECK(tick_clock_);
DCHECK(last_rtt_notification_.is_null());
}
SocketWatcher::~SocketWatcher() = default;
bool SocketWatcher::ShouldNotifyUpdatedRTT() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
if (!run_rtt_callback_)
return false;
const base::TimeTicks now = tick_clock_->NowTicks();
if (task_runner_->RunsTasksInCurrentSequence()) {
// Enables socket watcher to send more frequent RTT observations when very
// few sockets are receiving data.
if (should_notify_rtt_callback_.Run(now))
return true;
}
// Do not allow incoming notifications if the last notification was more
// recent than |rtt_notifications_minimum_interval_| ago. This helps in
// reducing the overhead of obtaining the RTT values.
// Enables a socket watcher to send RTT observation, helps in reducing
// starvation by allowing every socket watcher to notify at least one RTT
// notification every |rtt_notifications_minimum_interval_| duration.
return now - last_rtt_notification_ >= rtt_notifications_minimum_interval_;
}
void SocketWatcher::OnUpdatedRTTAvailable(const base::TimeDelta& rtt) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// tcp_socket_posix may sometimes report RTT as 1 microsecond when the RTT was
// actually invalid. See:
// https://cs.chromium.org/chromium/src/net/socket/tcp_socket_posix.cc?rcl=7ad660e34f2a996e381a85b2a515263003b0c171&l=106.
// Connections to private address eg localhost because they typically have
// small rtt.
if (!allow_rtt_private_address_ && rtt <= base::Microseconds(1)) {
return;
}
if (!first_quic_rtt_notification_received_ &&
protocol_ == SocketPerformanceWatcherFactory::PROTOCOL_QUIC) {
// First RTT sample from QUIC connections may be synthetically generated,
// and may not reflect the actual network quality.
first_quic_rtt_notification_received_ = true;
return;
}
last_rtt_notification_ = tick_clock_->NowTicks();
task_runner_->PostTask(
FROM_HERE,
base::BindOnce(updated_rtt_observation_callback_, protocol_, rtt, host_));
}
void SocketWatcher::OnConnectionChanged() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
}
} // namespace net::nqe::internal
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