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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 "net/dns/dns_config_service.h"
#include "base/logging.h"
#include "net/base/ip_endpoint.h"
namespace net {
// Default values are taken from glibc resolv.h.
DnsConfig::DnsConfig()
: append_to_multi_label_name(true),
ndots(1),
timeout(base::TimeDelta::FromSeconds(5)),
attempts(2),
rotate(false),
edns0(false) {}
DnsConfig::~DnsConfig() {}
bool DnsConfig::Equals(const DnsConfig& d) const {
return EqualsIgnoreHosts(d) && (hosts == d.hosts);
}
bool DnsConfig::EqualsIgnoreHosts(const DnsConfig& d) const {
return (nameservers == d.nameservers) &&
(search == d.search) &&
(append_to_multi_label_name == d.append_to_multi_label_name) &&
(ndots == d.ndots) &&
(timeout == d.timeout) &&
(attempts == d.attempts) &&
(rotate == d.rotate) &&
(edns0 == d.edns0);
}
void DnsConfig::CopyIgnoreHosts(const DnsConfig& d) {
nameservers = d.nameservers;
search = d.search;
append_to_multi_label_name = d.append_to_multi_label_name;
ndots = d.ndots;
timeout = d.timeout;
attempts = d.attempts;
rotate = d.rotate;
edns0 = d.edns0;
}
DnsConfigService::DnsConfigService()
: have_config_(false),
have_hosts_(false),
need_update_(false) {}
DnsConfigService::~DnsConfigService() {}
void DnsConfigService::InvalidateConfig() {
DCHECK(CalledOnValidThread());
if (!have_config_)
return;
have_config_ = false;
StartTimer();
}
void DnsConfigService::InvalidateHosts() {
DCHECK(CalledOnValidThread());
if (!have_hosts_)
return;
have_hosts_ = false;
StartTimer();
}
void DnsConfigService::OnConfigRead(const DnsConfig& config) {
DCHECK(CalledOnValidThread());
DCHECK(config.IsValid());
if (!config.EqualsIgnoreHosts(dns_config_)) {
dns_config_.CopyIgnoreHosts(config);
need_update_ = true;
}
have_config_ = true;
if (have_hosts_)
OnCompleteConfig();
}
void DnsConfigService::OnHostsRead(const DnsHosts& hosts) {
DCHECK(CalledOnValidThread());
if (hosts != dns_config_.hosts) {
dns_config_.hosts = hosts;
need_update_ = true;
}
have_hosts_ = true;
if (have_config_)
OnCompleteConfig();
}
void DnsConfigService::StartTimer() {
DCHECK(CalledOnValidThread());
timer_.Stop();
// Give it a short timeout to come up with a valid config. Otherwise withdraw
// the config from the receiver. The goal is to avoid perceivable network
// outage (when using the wrong config) but at the same time avoid
// unnecessary Job aborts in HostResolverImpl. The signals come from multiple
// sources so it might receive multiple events during a config change.
// DHCP and user-induced changes are on the order of seconds, so 100ms should
// not add perceivable delay. On the other hand, config readers should finish
// within 100ms with the rare exception of I/O block or extra large HOSTS.
const base::TimeDelta kTimeout = base::TimeDelta::FromMilliseconds(100);
timer_.Start(FROM_HERE,
kTimeout,
this,
&DnsConfigService::OnTimeout);
}
void DnsConfigService::OnTimeout() {
DCHECK(CalledOnValidThread());
// Indicate that even if there is no change in On*Read, we will need to
// update the receiver when the config becomes complete.
need_update_ = true;
// Empty config is considered invalid.
callback_.Run(DnsConfig());
}
void DnsConfigService::OnCompleteConfig() {
timer_.Stop();
if (need_update_) {
need_update_ = false;
callback_.Run(dns_config_);
}
}
} // namespace net
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