[net/dns] Treat Name Resolution Policy Table as unhandled option.

net/dns/host_resolver_impl.cc

 // 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/host_resolver_impl.h"
 
 #if defined(OS_WIN)
 #include <Winsock2.h>
 #elif defined(OS_POSIX)
 #include <netdb.h>
@@ skipping 1781 matching lines @@
       dispatcher_(job_limits),
       max_queued_jobs_(job_limits.total_jobs * 100u),
       proc_params_(proc_params),
       net_log_(net_log),
       default_address_family_(ADDRESS_FAMILY_UNSPECIFIED),
       weak_ptr_factory_(this),
       probe_weak_ptr_factory_(this),
       received_dns_config_(false),
       num_dns_failures_(0),
       probe_ipv6_support_(true),
+      use_local_ipv6_(false),
       resolved_known_ipv6_hostname_(false),
       additional_resolver_flags_(0),
       fallback_to_proctask_(true) {
 
   DCHECK_GE(dispatcher_.num_priorities(), static_cast<size_t>(NUM_PRIORITIES));
 
   // Maximum of 4 retry attempts for host resolution.
   static const size_t kDefaultMaxRetryAttempts = 4u;
 
   if (proc_params_.max_retry_attempts == HostResolver::kDefaultRetryAttempts)
     proc_params_.max_retry_attempts = kDefaultMaxRetryAttempts;
 
 #if defined(OS_WIN)
   EnsureWinsockInit();
 #endif
 #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
   new LoopbackProbeJob(weak_ptr_factory_.GetWeakPtr());
 #endif
   NetworkChangeNotifier::AddIPAddressObserver(this);
   NetworkChangeNotifier::AddDNSObserver(this);
 #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD) && \
     !defined(OS_ANDROID)
   EnsureDnsReloaderInit();
 #endif
 
-  // TODO(szym): Remove when received_dns_config_ is removed, once
-  // http://crbug.com/137914 is resolved.
   {
     DnsConfig dns_config;
     NetworkChangeNotifier::GetDnsConfig(&dns_config);
     received_dns_config_ = dns_config.IsValid();
+    // Conservatively assume local IPv6 is needed when DnsConfig is not valid.
+    use_local_ipv6_ = !dns_config.IsValid() || dns_config.use_local_ipv6;
   }
 
   fallback_to_proctask_ = !ConfigureAsyncDnsNoFallbackFieldTrial();
 }
 
 HostResolverImpl::~HostResolverImpl() {
   // Prevent the dispatcher from starting new jobs.
   dispatcher_.SetLimitsToZero();
   // It's now safe for Jobs to call KillDsnTask on destruction, because
   // OnJobComplete will not start any new jobs.
@@ skipping 292 matching lines @@
   }
 }
 
 HostResolverImpl::Key HostResolverImpl::GetEffectiveKeyForRequest(
     const RequestInfo& info, const BoundNetLog& net_log) const {
   HostResolverFlags effective_flags =
       info.host_resolver_flags() | additional_resolver_flags_;
   AddressFamily effective_address_family = info.address_family();
 
   if (info.address_family() == ADDRESS_FAMILY_UNSPECIFIED) {
-    if (probe_ipv6_support_) {
+    if (probe_ipv6_support_ && !use_local_ipv6_) {
       base::TimeTicks start_time = base::TimeTicks::Now();
       // Google DNS address.
       const uint8 kIPv6Address[] =
           { 0x20, 0x01, 0x48, 0x60, 0x48, 0x60, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x88, 0x88 };
       IPAddressNumber address(kIPv6Address,
                               kIPv6Address + arraysize(kIPv6Address));
       bool rv6 = IsGloballyReachable(address, net_log);
       if (rv6)
         net_log.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_IPV6_SUPPORTED);
@@ skipping 103 matching lines @@
   NetworkChangeNotifier::GetDnsConfig(&dns_config);
 
   if (net_log_) {
     net_log_->AddGlobalEntry(
         NetLog::TYPE_DNS_CONFIG_CHANGED,
         base::Bind(&NetLogDnsConfigCallback, &dns_config));
   }
 
   // TODO(szym): Remove once http://crbug.com/137914 is resolved.
   received_dns_config_ = dns_config.IsValid();
+  // Conservatively assume local IPv6 is needed when DnsConfig is not valid.
+  use_local_ipv6_ = !dns_config.IsValid() || dns_config.use_local_ipv6;
 
   num_dns_failures_ = 0;
 
   // We want a new DnsSession in place, before we Abort running Jobs, so that
   // the newly started jobs use the new config.
   if (dns_client_.get()) {
     dns_client_->SetConfig(dns_config);
     if (dns_client_->GetConfig())
       UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true);
   }
@@ skipping 61 matching lines @@
     dns_client_->SetConfig(dns_config);
     num_dns_failures_ = 0;
     if (dns_client_->GetConfig())
       UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true);
   }
 
   AbortDnsTasks();
 }
 
 }  // namespace net