[net/dns] Test IPv6 support via UDP connect (measurement)

net/dns/host_resolver_impl.cc

Index: net/dns/host_resolver_impl.cc
diff --git a/net/dns/host_resolver_impl.cc b/net/dns/host_resolver_impl.cc
index abb34d845e2c6db153475aef0504c0649035a42b..9a082fb11c9a4c265f90381251d00e0308e9848e 100644
--- a/net/dns/host_resolver_impl.cc
+++ b/net/dns/host_resolver_impl.cc
@@ -44,6 +44,8 @@
 #include "net/dns/dns_response.h"
 #include "net/dns/dns_transaction.h"
 #include "net/dns/host_resolver_proc.h"
+#include "net/socket/client_socket_factory.h"
+#include "net/udp/datagram_client_socket.h"
 
 #if defined(OS_WIN)
 #include "net/base/winsock_init.h"
@@ -167,6 +169,17 @@ bool ResemblesMulticastDNSName(const std::string& hostname) {
                         kSuffix, kSuffixLenTrimmed);
 }
 
+// Attempts to connect a UDP socket to |dest|:80.
+int AttemptRoute(const IPAddressNumber& dest) {
+  scoped_ptr<DatagramClientSocket> socket(
+      ClientSocketFactory::GetDefaultFactory()->CreateDatagramClientSocket(
+          DatagramSocket::DEFAULT_BIND,
+          RandIntCallback(),
+          NULL,
+          NetLog::Source()));
+  return socket->Connect(IPEndPoint(dest, 80));

[lorenzo, 2013/04/11 07:28:14]

Do you need to check that the address is a global address as well? That's what
the existing IPv6 probe does I think.

It's possible that some operating systems (perhaps OS X; Linux doesn't do this),
will try to connect to a global address even if they only have a link-local
address (which is very unlikely to work). On these systems, the connection probe
could return success even if there was no global address present on the machine.

If that's the case, you can call getsockname() to get the IP address the OS
picked for the connection and see if it's a global address.

+}
+
 // Provide a common macro to simplify code and readability. We must use a
 // macro as the underlying HISTOGRAM macro creates static variables.
 #define DNS_HISTOGRAM(name, time) UMA_HISTOGRAM_CUSTOM_TIMES(name, time, \
@@ -888,6 +901,7 @@ class HostResolverImpl::ProcTask
 
 // Wraps a call to TestIPv6Support to be executed on the WorkerPool as it takes
 // 40-100ms.
+// TODO(szym): Remove altogether, if IPv6ActiveProbe works.
 class HostResolverImpl::IPv6ProbeJob {
  public:
   IPv6ProbeJob(const base::WeakPtr<HostResolverImpl>& resolver, NetLog* net_log)
@@ -1858,6 +1872,7 @@ AddressFamily HostResolverImpl::GetDefaultAddressFamily() const {
   return default_address_family_;
 }
 
+// TODO(szym): Remove this API altogether if IPv6ActiveProbe works.
 void HostResolverImpl::ProbeIPv6Support() {
   DCHECK(CalledOnValidThread());
   DCHECK(!ipv6_probe_monitoring_);
@@ -2023,12 +2038,34 @@ HostResolverImpl::Key HostResolverImpl::GetEffectiveKeyForRequest(
   HostResolverFlags effective_flags =
       info.host_resolver_flags() | additional_resolver_flags_;
   AddressFamily effective_address_family = info.address_family();
+
+  if (info.address_family() == ADDRESS_FAMILY_UNSPECIFIED) {
+    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 };
+    int rv6 = AttemptRoute(
+        IPAddressNumber(kIPv6Address, kIPv6Address + arraysize(kIPv6Address)));
+
+    UMA_HISTOGRAM_TIMES("Net.IPv6ConnectDuration",
+                        base::TimeTicks::Now() - start_time);
+    if (rv6 == OK) {
+      UMA_HISTOGRAM_BOOLEAN("Net.IPv6ConnectSuccessMatch",
+          default_address_family_ == ADDRESS_FAMILY_UNSPECIFIED);
+    } else {
+      UMA_HISTOGRAM_BOOLEAN("Net.IPv6ConnectFailureMatch",
+          default_address_family_ != ADDRESS_FAMILY_UNSPECIFIED);
+    }
+  }
+
   if (effective_address_family == ADDRESS_FAMILY_UNSPECIFIED &&
       default_address_family_ != ADDRESS_FAMILY_UNSPECIFIED) {
     effective_address_family = default_address_family_;
     if (ipv6_probe_monitoring_)
       effective_flags |= HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6;
   }
+
   return Key(info.hostname(), effective_address_family, effective_flags);
 }