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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/net/dns_probe_service.h"
#include "base/metrics/histogram.h"
#include "chrome/browser/net/dns_probe_job.h"
#include "net/base/ip_endpoint.h"
#include "net/base/net_util.h"
#include "net/base/network_change_notifier.h"
#include "net/dns/dns_client.h"
#include "net/dns/dns_config_service.h"
#include "net/dns/dns_protocol.h"
using net::DnsClient;
using net::DnsConfig;
using net::IPAddressNumber;
using net::IPEndPoint;
using net::ParseIPLiteralToNumber;
using net::NetworkChangeNotifier;
namespace chrome_browser_net {
namespace {
const char kPublicDnsPrimary[] = "8.8.8.8";
const char kPublicDnsSecondary[] = "8.8.4.4";
IPEndPoint MakeDnsEndPoint(const std::string& dns_ip_literal) {
IPAddressNumber dns_ip_number;
bool rv = ParseIPLiteralToNumber(dns_ip_literal, &dns_ip_number);
DCHECK(rv);
return IPEndPoint(dns_ip_number, net::dns_protocol::kDefaultPort);
}
const int kMaxResultAgeMs = 5000;
} // namespace
DnsProbeService::DnsProbeService()
: system_result_(DnsProbeJob::SERVERS_UNKNOWN),
public_result_(DnsProbeJob::SERVERS_UNKNOWN),
state_(STATE_NO_RESULTS),
result_(PROBE_UNKNOWN) {
}
DnsProbeService::~DnsProbeService() {
}
void DnsProbeService::ProbeDns(const DnsProbeService::CallbackType& callback) {
callbacks_.push_back(callback);
if (state_ == STATE_RESULTS_CACHED && ResultsExpired())
ExpireResults();
switch (state_) {
case STATE_NO_RESULTS:
StartProbes();
break;
case STATE_RESULTS_CACHED:
CallCallbacks();
break;
case STATE_PROBE_RUNNING:
// do nothing; probe is already running, and will call the callback
break;
}
}
scoped_ptr<DnsProbeJob> DnsProbeService::CreateSystemProbeJob(
const DnsProbeJob::CallbackType& job_callback) {
DnsConfig system_config;
GetSystemDnsConfig(&system_config);
return CreateProbeJob(system_config, job_callback);
}
scoped_ptr<DnsProbeJob> DnsProbeService::CreatePublicProbeJob(
const DnsProbeJob::CallbackType& job_callback) {
DnsConfig public_config;
GetPublicDnsConfig(&public_config);
return CreateProbeJob(public_config, job_callback);
}
void DnsProbeService::ExpireResults() {
DCHECK_EQ(STATE_RESULTS_CACHED, state_);
state_ = STATE_NO_RESULTS;
result_ = PROBE_UNKNOWN;
}
void DnsProbeService::StartProbes() {
DCHECK_NE(STATE_PROBE_RUNNING, state_);
DCHECK(!system_job_.get());
DCHECK(!public_job_.get());
DnsProbeJob::CallbackType job_callback =
base::Bind(&DnsProbeService::OnProbeJobComplete,
base::Unretained(this));
// TODO(ttuttle): Do we want to keep explicit flags for "job done"?
// Or maybe DnsProbeJob should have a "finished" flag?
system_result_ = DnsProbeJob::SERVERS_UNKNOWN;
public_result_ = DnsProbeJob::SERVERS_UNKNOWN;
system_job_ = CreateSystemProbeJob(job_callback);
public_job_ = CreatePublicProbeJob(job_callback);
state_ = STATE_PROBE_RUNNING;
probe_start_time_ = base::Time::Now();
}
void DnsProbeService::OnProbesComplete() {
DCHECK_EQ(STATE_PROBE_RUNNING, state_);
base::TimeDelta probe_elapsed = base::Time::Now() - probe_start_time_;
UMA_HISTOGRAM_ENUMERATION("DnsProbe.Probe.Result", result_, MAX_RESULT);
UMA_HISTOGRAM_MEDIUM_TIMES("DnsProbe.Probe.Elapsed", probe_elapsed);
state_ = STATE_RESULTS_CACHED;
result_ = EvaluateResults();
CallCallbacks();
}
DnsProbeService::Result DnsProbeService::EvaluateResults() {
DCHECK_NE(DnsProbeJob::SERVERS_UNKNOWN, system_result_);
DCHECK_NE(DnsProbeJob::SERVERS_UNKNOWN, public_result_);
// If the system DNS is working, assume the domain doesn't exist.
if (system_result_ == DnsProbeJob::SERVERS_CORRECT)
return PROBE_NXDOMAIN;
// If the system DNS is not working but another public server is, assume the
// DNS config is bad (or perhaps the DNS servers are down or broken).
if (public_result_ == DnsProbeJob::SERVERS_CORRECT)
return PROBE_BAD_CONFIG;
// If the system DNS is not working and another public server is unreachable,
// assume the internet connection is down (note that system DNS may be a
// router on the LAN, so it may be reachable but returning errors.)
if (public_result_ == DnsProbeJob::SERVERS_UNREACHABLE)
return PROBE_NO_INTERNET;
// Otherwise: the system DNS is not working and another public server is
// responding but with errors or incorrect results. This is an awkward case;
// an invasive captive portal or a restrictive firewall may be intercepting
// or rewriting DNS traffic, or the public server may itself be failing or
// down.
return PROBE_UNKNOWN;
}
void DnsProbeService::CallCallbacks() {
DCHECK_EQ(STATE_RESULTS_CACHED, state_);
DCHECK(!callbacks_.empty());
std::vector<CallbackType> callbacks = callbacks_;
callbacks_.clear();
for (std::vector<CallbackType>::const_iterator i = callbacks.begin();
i != callbacks.end(); ++i) {
i->Run(result_);
}
}
scoped_ptr<DnsProbeJob> DnsProbeService::CreateProbeJob(
const DnsConfig& dns_config,
const DnsProbeJob::CallbackType& job_callback) {
scoped_ptr<DnsClient> dns_client(DnsClient::CreateClient(NULL));
dns_client->SetConfig(dns_config);
return DnsProbeJob::CreateJob(dns_client.Pass(), job_callback, NULL);
}
void DnsProbeService::OnProbeJobComplete(DnsProbeJob* job,
DnsProbeJob::Result result) {
DCHECK_EQ(STATE_PROBE_RUNNING, state_);
if (job == system_job_.get()) {
system_result_ = result;
system_job_.reset();
} else if (job == public_job_.get()) {
public_result_ = result;
public_job_.reset();
} else {
NOTREACHED();
return;
}
if (system_result_ != DnsProbeJob::SERVERS_UNKNOWN &&
public_result_ != DnsProbeJob::SERVERS_UNKNOWN) {
OnProbesComplete();
}
}
void DnsProbeService::GetSystemDnsConfig(DnsConfig* config) {
// TODO(ttuttle): Make sure we handle missing config properly
NetworkChangeNotifier::GetDnsConfig(config);
}
void DnsProbeService::GetPublicDnsConfig(DnsConfig* config) {
*config = DnsConfig();
config->nameservers.push_back(MakeDnsEndPoint(kPublicDnsPrimary));
config->nameservers.push_back(MakeDnsEndPoint(kPublicDnsSecondary));
}
bool DnsProbeService::ResultsExpired() {
const base::TimeDelta kMaxResultAge =
base::TimeDelta::FromMilliseconds(kMaxResultAgeMs);
return base::Time::Now() - probe_start_time_ > kMaxResultAge;
}
} // namespace chrome_browser_net
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