net/dns/dns_config_service.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/dns/dns_config_service.h"
   6
   7 #include "base/logging.h"
   8 #include "base/metrics/histogram.h"
   9 #include "base/values.h"
  10 #include "net/base/ip_endpoint.h"
  11 #include "net/base/ip_pattern.h"
  12
  13 namespace net {
  14
  15 NameServerClassifier::NameServerClassifier() {
  16   // Google Public DNS addresses from:
  17   // https://developers.google.com/speed/public-dns/docs/using
  18   AddRule("8.8.8.8", NAME_SERVERS_TYPE_GOOGLE_PUBLIC_DNS);
  19   AddRule("8.8.4.4", NAME_SERVERS_TYPE_GOOGLE_PUBLIC_DNS);
  20   AddRule("2001:4860:4860:0:0:0:0:8888", NAME_SERVERS_TYPE_GOOGLE_PUBLIC_DNS),
  21   AddRule("2001:4860:4860:0:0:0:0:8844", NAME_SERVERS_TYPE_GOOGLE_PUBLIC_DNS),
  22
  23   // Count localhost as private, since we don't know what upstream it uses:
  24   AddRule("127.*.*.*", NAME_SERVERS_TYPE_PRIVATE);
  25   AddRule("0:0:0:0:0:0:0:1", NAME_SERVERS_TYPE_PRIVATE);
  26
  27   // RFC 1918 private addresses:
  28   AddRule("10.*.*.*", NAME_SERVERS_TYPE_PRIVATE);
  29   AddRule("172.[16-31].*.*", NAME_SERVERS_TYPE_PRIVATE);
  30   AddRule("192.168.*.*", NAME_SERVERS_TYPE_PRIVATE);
  31
  32   // IPv4 link-local addresses:
  33   AddRule("169.254.*.*", NAME_SERVERS_TYPE_PRIVATE);
  34
  35   // IPv6 link-local addresses:
  36   AddRule("fe80:*:*:*:*:*:*:*", NAME_SERVERS_TYPE_PRIVATE);
  37
  38   // Anything else counts as public:
  39   AddRule("*.*.*.*", NAME_SERVERS_TYPE_PUBLIC);
  40   AddRule("*:*:*:*:*:*:*:*", NAME_SERVERS_TYPE_PUBLIC);
  41 }
  42
  43 NameServerClassifier::~NameServerClassifier() {}
  44
  45 NameServerClassifier::NameServersType NameServerClassifier::GetNameServersType(
  46     const std::vector<IPEndPoint>& nameservers) const {
  47   NameServersType type = NAME_SERVERS_TYPE_NONE;
  48   for (std::vector<IPEndPoint>::const_iterator it = nameservers.begin();
  49        it != nameservers.end();
  50        ++it) {
  51     type = MergeNameServersTypes(type, GetNameServerType(it->address()));
  52   }
  53   return type;
  54 }
  55
  56 struct NameServerClassifier::NameServerTypeRule {
  57   NameServerTypeRule(const char* pattern_string, NameServersType type)
  58       : type(type) {
  59     bool parsed = pattern.ParsePattern(pattern_string);
  60     DCHECK(parsed);
  61   }
  62
  63   IPPattern pattern;
  64   NameServersType type;
  65 };
  66
  67 void NameServerClassifier::AddRule(const char* pattern_string,
  68                                    NameServersType address_type) {
  69   rules_.push_back(new NameServerTypeRule(pattern_string, address_type));
  70 }
  71
  72 NameServerClassifier::NameServersType NameServerClassifier::GetNameServerType(
  73     const IPAddressNumber& address) const {
  74   for (ScopedVector<NameServerTypeRule>::const_iterator it = rules_.begin();
  75        it != rules_.end();
  76        ++it) {
  77     if ((*it)->pattern.Match(address))
  78       return (*it)->type;
  79   }
  80   NOTREACHED();
  81   return NAME_SERVERS_TYPE_NONE;
  82 }
  83
  84 NameServerClassifier::NameServersType
  85 NameServerClassifier::MergeNameServersTypes(NameServersType a,
  86                                             NameServersType b) {
  87   if (a == NAME_SERVERS_TYPE_NONE)
  88     return b;
  89   if (b == NAME_SERVERS_TYPE_NONE)
  90     return a;
  91   if (a == b)
  92     return a;
  93   return NAME_SERVERS_TYPE_MIXED;
  94 }
  95
  96 // Default values are taken from glibc resolv.h except timeout which is set to
  97 // |kDnsTimeoutSeconds|.
  98 DnsConfig::DnsConfig()
  99     : unhandled_options(false),
 100       append_to_multi_label_name(true),
 101       randomize_ports(false),
 102       ndots(1),
 103       timeout(base::TimeDelta::FromSeconds(kDnsTimeoutSeconds)),
 104       attempts(2),
 105       rotate(false),
 106       edns0(false),
 107       use_local_ipv6(false) {}
 108
 109 DnsConfig::~DnsConfig() {}
 110
 111 bool DnsConfig::Equals(const DnsConfig& d) const {
 112   return EqualsIgnoreHosts(d) && (hosts == d.hosts);
 113 }
 114
 115 bool DnsConfig::EqualsIgnoreHosts(const DnsConfig& d) const {
 116   return (nameservers == d.nameservers) &&
 117          (search == d.search) &&
 118          (unhandled_options == d.unhandled_options) &&
 119          (append_to_multi_label_name == d.append_to_multi_label_name) &&
 120          (ndots == d.ndots) &&
 121          (timeout == d.timeout) &&
 122          (attempts == d.attempts) &&
 123          (rotate == d.rotate) &&
 124          (edns0 == d.edns0) &&
 125          (use_local_ipv6 == d.use_local_ipv6);
 126 }
 127
 128 void DnsConfig::CopyIgnoreHosts(const DnsConfig& d) {
 129   nameservers = d.nameservers;
 130   search = d.search;
 131   unhandled_options = d.unhandled_options;
 132   append_to_multi_label_name = d.append_to_multi_label_name;
 133   ndots = d.ndots;
 134   timeout = d.timeout;
 135   attempts = d.attempts;
 136   rotate = d.rotate;
 137   edns0 = d.edns0;
 138   use_local_ipv6 = d.use_local_ipv6;
 139 }
 140
 141 base::Value* DnsConfig::ToValue() const {
 142   base::DictionaryValue* dict = new base::DictionaryValue();
 143
 144   base::ListValue* list = new base::ListValue();
 145   for (size_t i = 0; i < nameservers.size(); ++i)
 146     list->Append(new base::StringValue(nameservers[i].ToString()));
 147   dict->Set("nameservers", list);
 148
 149   list = new base::ListValue();
 150   for (size_t i = 0; i < search.size(); ++i)
 151     list->Append(new base::StringValue(search[i]));
 152   dict->Set("search", list);
 153
 154   dict->SetBoolean("unhandled_options", unhandled_options);
 155   dict->SetBoolean("append_to_multi_label_name", append_to_multi_label_name);
 156   dict->SetInteger("ndots", ndots);
 157   dict->SetDouble("timeout", timeout.InSecondsF());
 158   dict->SetInteger("attempts", attempts);
 159   dict->SetBoolean("rotate", rotate);
 160   dict->SetBoolean("edns0", edns0);
 161   dict->SetBoolean("use_local_ipv6", use_local_ipv6);
 162   dict->SetInteger("num_hosts", hosts.size());
 163
 164   return dict;
 165 }
 166
 167
 168 DnsConfigService::DnsConfigService()
 169     : watch_failed_(false),
 170       have_config_(false),
 171       have_hosts_(false),
 172       need_update_(false),
 173       last_sent_empty_(true) {}
 174
 175 DnsConfigService::~DnsConfigService() {
 176 }
 177
 178 void DnsConfigService::ReadConfig(const CallbackType& callback) {
 179   DCHECK(CalledOnValidThread());
 180   DCHECK(!callback.is_null());
 181   DCHECK(callback_.is_null());
 182   callback_ = callback;
 183   ReadNow();
 184 }
 185
 186 void DnsConfigService::WatchConfig(const CallbackType& callback) {
 187   DCHECK(CalledOnValidThread());
 188   DCHECK(!callback.is_null());
 189   DCHECK(callback_.is_null());
 190   callback_ = callback;
 191   watch_failed_ = !StartWatching();
 192   ReadNow();
 193 }
 194
 195 void DnsConfigService::InvalidateConfig() {
 196   DCHECK(CalledOnValidThread());
 197   base::TimeTicks now = base::TimeTicks::Now();
 198   if (!last_invalidate_config_time_.is_null()) {
 199     UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.ConfigNotifyInterval",
 200                              now - last_invalidate_config_time_);
 201   }
 202   last_invalidate_config_time_ = now;
 203   if (!have_config_)
 204     return;
 205   have_config_ = false;
 206   StartTimer();
 207 }
 208
 209 void DnsConfigService::InvalidateHosts() {
 210   DCHECK(CalledOnValidThread());
 211   base::TimeTicks now = base::TimeTicks::Now();
 212   if (!last_invalidate_hosts_time_.is_null()) {
 213     UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.HostsNotifyInterval",
 214                              now - last_invalidate_hosts_time_);
 215   }
 216   last_invalidate_hosts_time_ = now;
 217   if (!have_hosts_)
 218     return;
 219   have_hosts_ = false;
 220   StartTimer();
 221 }
 222
 223 void DnsConfigService::OnConfigRead(const DnsConfig& config) {
 224   DCHECK(CalledOnValidThread());
 225   DCHECK(config.IsValid());
 226
 227   bool changed = false;
 228   if (!config.EqualsIgnoreHosts(dns_config_)) {
 229     dns_config_.CopyIgnoreHosts(config);
 230     need_update_ = true;
 231     changed = true;
 232   }
 233   if (!changed && !last_sent_empty_time_.is_null()) {
 234     UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.UnchangedConfigInterval",
 235                              base::TimeTicks::Now() - last_sent_empty_time_);
 236   }
 237   UMA_HISTOGRAM_BOOLEAN("AsyncDNS.ConfigChange", changed);
 238   UMA_HISTOGRAM_ENUMERATION(
 239       "AsyncDNS.NameServersType",
 240       classifier_.GetNameServersType(dns_config_.nameservers),
 241       NameServerClassifier::NAME_SERVERS_TYPE_MAX_VALUE);
 242
 243   have_config_ = true;
 244   if (have_hosts_ || watch_failed_)
 245     OnCompleteConfig();
 246 }
 247
 248 void DnsConfigService::OnHostsRead(const DnsHosts& hosts) {
 249   DCHECK(CalledOnValidThread());
 250
 251   bool changed = false;
 252   if (hosts != dns_config_.hosts) {
 253     dns_config_.hosts = hosts;
 254     need_update_ = true;
 255     changed = true;
 256   }
 257   if (!changed && !last_sent_empty_time_.is_null()) {
 258     UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.UnchangedHostsInterval",
 259                              base::TimeTicks::Now() - last_sent_empty_time_);
 260   }
 261   UMA_HISTOGRAM_BOOLEAN("AsyncDNS.HostsChange", changed);
 262
 263   have_hosts_ = true;
 264   if (have_config_ || watch_failed_)
 265     OnCompleteConfig();
 266 }
 267
 268 void DnsConfigService::StartTimer() {
 269   DCHECK(CalledOnValidThread());
 270   if (last_sent_empty_) {
 271     DCHECK(!timer_.IsRunning());
 272     return;  // No need to withdraw again.
 273   }
 274   timer_.Stop();
 275
 276   // Give it a short timeout to come up with a valid config. Otherwise withdraw
 277   // the config from the receiver. The goal is to avoid perceivable network
 278   // outage (when using the wrong config) but at the same time avoid
 279   // unnecessary Job aborts in HostResolverImpl. The signals come from multiple
 280   // sources so it might receive multiple events during a config change.
 281
 282   // DHCP and user-induced changes are on the order of seconds, so 150ms should
 283   // not add perceivable delay. On the other hand, config readers should finish
 284   // within 150ms with the rare exception of I/O block or extra large HOSTS.
 285   const base::TimeDelta kTimeout = base::TimeDelta::FromMilliseconds(150);
 286
 287   timer_.Start(FROM_HERE,
 288                kTimeout,
 289                this,
 290                &DnsConfigService::OnTimeout);
 291 }
 292
 293 void DnsConfigService::OnTimeout() {
 294   DCHECK(CalledOnValidThread());
 295   DCHECK(!last_sent_empty_);
 296   // Indicate that even if there is no change in On*Read, we will need to
 297   // update the receiver when the config becomes complete.
 298   need_update_ = true;
 299   // Empty config is considered invalid.
 300   last_sent_empty_ = true;
 301   last_sent_empty_time_ = base::TimeTicks::Now();
 302   callback_.Run(DnsConfig());
 303 }
 304
 305 void DnsConfigService::OnCompleteConfig() {
 306   timer_.Stop();
 307   if (!need_update_)
 308     return;
 309   need_update_ = false;
 310   last_sent_empty_ = false;
 311   if (watch_failed_) {
 312     // If a watch failed, the config may not be accurate, so report empty.
 313     callback_.Run(DnsConfig());
 314   } else {
 315     callback_.Run(dns_config_);
 316   }
 317 }
 318
 319 }  // namespace net
 320