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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_job.h"
#include "base/memory/scoped_ptr.h"
#include "base/message_loop.h"
#include "base/time.h"
#include "net/base/address_list.h"
#include "net/base/net_errors.h"
#include "net/base/net_log.h"
#include "net/dns/dns_client.h"
#include "net/dns/dns_protocol.h"
#include "net/dns/dns_response.h"
#include "net/dns/dns_transaction.h"
using base::TimeDelta;
using net::AddressList;
using net::BoundNetLog;
using net::DnsClient;
using net::DnsResponse;
using net::DnsTransaction;
using net::NetLog;
namespace chrome_browser_net {
namespace {
class DnsProbeJobImpl : public DnsProbeJob {
public:
DnsProbeJobImpl(scoped_ptr<DnsClient> dns_client,
const DnsProbeJob::CallbackType& callback,
NetLog* net_log);
virtual ~DnsProbeJobImpl();
private:
enum QueryResult {
QUERY_UNKNOWN,
QUERY_CORRECT,
QUERY_INCORRECT,
QUERY_DNS_ERROR,
QUERY_NET_ERROR,
};
scoped_ptr<DnsTransaction> CreateTransaction(
const std::string& hostname);
void StartTransaction(DnsTransaction* transaction);
// Checks that |net_error| is OK, |response| parses, and has at least one
// address.
QueryResult EvaluateGoodResponse(int net_error, const DnsResponse* response);
// Checks that |net_error| is OK, |response| parses but has no addresses.
QueryResult EvaluateBadResponse(int net_error, const DnsResponse* response);
DnsProbeJob::Result EvaluateQueryResults();
void OnTransactionComplete(DnsTransaction* transaction,
int net_error,
const DnsResponse* response);
void RunCallback(DnsProbeJob::Result result);
BoundNetLog bound_net_log_;
scoped_ptr<DnsClient> dns_client_;
const DnsProbeJob::CallbackType callback_;
scoped_ptr<DnsTransaction> good_transaction_;
scoped_ptr<DnsTransaction> bad_transaction_;
bool good_running_;
bool bad_running_;
QueryResult good_result_;
QueryResult bad_result_;
DISALLOW_COPY_AND_ASSIGN(DnsProbeJobImpl);
};
DnsProbeJobImpl::DnsProbeJobImpl(scoped_ptr<DnsClient> dns_client,
const DnsProbeJob::CallbackType& callback,
NetLog* net_log)
: bound_net_log_(
BoundNetLog::Make(net_log, NetLog::SOURCE_DNS_PROBER)),
dns_client_(dns_client.Pass()),
callback_(callback),
good_running_(false),
bad_running_(false),
good_result_(QUERY_UNKNOWN),
bad_result_(QUERY_UNKNOWN) {
DCHECK(dns_client_.get());
DCHECK(dns_client_->GetConfig());
// TODO(ttuttle): Pick a good random hostname for the bad case.
// Consider running transactions in series?
good_transaction_ = CreateTransaction("google.com");
bad_transaction_ = CreateTransaction("thishostname.doesnotresolve");
// StartTransaction may call the callback synchrononously, so set these
// before we call it.
good_running_ = true;
bad_running_ = true;
// TODO(ttuttle): Log probe started.
StartTransaction(good_transaction_.get());
StartTransaction(bad_transaction_.get());
}
DnsProbeJobImpl::~DnsProbeJobImpl() {
}
scoped_ptr<DnsTransaction> DnsProbeJobImpl::CreateTransaction(
const std::string& hostname) {
return dns_client_->GetTransactionFactory()->CreateTransaction(
hostname,
net::dns_protocol::kTypeA,
base::Bind(&DnsProbeJobImpl::OnTransactionComplete,
base::Unretained(this)),
bound_net_log_);
}
void DnsProbeJobImpl::StartTransaction(DnsTransaction* transaction) {
int rv = transaction->Start();
if (rv != net::ERR_IO_PENDING) {
// TODO(ttuttle): Make sure this counts as unreachable, not error.
OnTransactionComplete(transaction, rv, NULL);
}
// TODO(ttuttle): Log transaction started.
}
DnsProbeJobImpl::QueryResult DnsProbeJobImpl::EvaluateGoodResponse(
int net_error,
const DnsResponse* response) {
if (net_error != net::OK)
return QUERY_NET_ERROR;
AddressList addr_list;
TimeDelta ttl;
DnsResponse::Result result = response->ParseToAddressList(&addr_list, &ttl);
if (result != DnsResponse::DNS_PARSE_OK)
return QUERY_DNS_ERROR;
if (addr_list.empty())
return QUERY_INCORRECT;
return QUERY_CORRECT;
}
DnsProbeJobImpl::QueryResult DnsProbeJobImpl::EvaluateBadResponse(
int net_error,
const DnsResponse* response) {
if (net_error == net::ERR_NAME_NOT_RESOLVED) // NXDOMAIN maps to this
return QUERY_CORRECT;
// TODO(ttuttle): Examine net_error a little more closely to see whether
// it's a DNS error or a network error.
if (net_error != net::OK)
return QUERY_NET_ERROR;
return QUERY_INCORRECT;
}
DnsProbeJob::Result DnsProbeJobImpl::EvaluateQueryResults() {
if (good_result_ == QUERY_NET_ERROR || bad_result_ == QUERY_NET_ERROR)
return SERVERS_UNREACHABLE;
if (good_result_ == QUERY_DNS_ERROR || bad_result_ == QUERY_DNS_ERROR)
return SERVERS_FAILING;
// Ignore incorrect responses to known-bad query to avoid flagging domain
// helpers.
if (good_result_ == QUERY_INCORRECT)
return SERVERS_INCORRECT;
return SERVERS_CORRECT;
}
void DnsProbeJobImpl::OnTransactionComplete(DnsTransaction* transaction,
int net_error,
const DnsResponse* response) {
if (transaction == good_transaction_.get()) {
DCHECK(good_running_);
DCHECK_EQ(QUERY_UNKNOWN, good_result_);
good_result_ = EvaluateGoodResponse(net_error, response);
good_running_ = false;
} else if (transaction == bad_transaction_.get()) {
DCHECK(bad_running_);
DCHECK_EQ(QUERY_UNKNOWN, bad_result_);
bad_result_ = EvaluateBadResponse(net_error, response);
bad_running_ = false;
} else {
NOTREACHED();
return;
}
if (good_running_ || bad_running_)
return;
RunCallback(EvaluateQueryResults());
// TODO(ttuttle): Log probe finished.
}
void DnsProbeJobImpl::RunCallback(DnsProbeJob::Result result) {
// Make sure we're not running the callback in the constructor.
// This avoids a race where our owner tries to destroy us while we're still
// being created, then ends up with a dangling pointer to us.
MessageLoop::current()->PostTask(
FROM_HERE,
base::Bind(callback_, base::Unretained(this), result));
}
} // namespace
scoped_ptr<DnsProbeJob> DnsProbeJob::CreateJob(
scoped_ptr<DnsClient> dns_client,
const CallbackType& callback,
NetLog* net_log) {
return scoped_ptr<DnsProbeJob>(
new DnsProbeJobImpl(dns_client.Pass(), callback, net_log));
}
} // namespace chrome_browser_net
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