Bypass data reduction proxy when using VPN

components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc

Index: components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc
diff --git a/components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc b/components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc
index cc575c94c3f6ef5e5cabd93855ed99cb89d94dd7..db8f40fd0da3c64d07e1cc6600adf8b0e7e6cbe8 100644
--- a/components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc
+++ b/components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc
@@ -24,6 +24,7 @@
 #include "net/base/host_port_pair.h"
 #include "net/base/load_flags.h"
 #include "net/base/net_errors.h"
+#include "net/base/net_util.h"
 #include "net/http/http_network_session.h"
 #include "net/http/http_response_headers.h"
 #include "net/url_request/url_fetcher.h"
@@ -36,6 +37,19 @@
 using base::StringPrintf;
 
 namespace {
+// Values of the UMA DataReductionProxy.NetworkChangeEvents histograms.
+// This enum must remain synchronized with the enum of the same
+// name in metrics/histograms/histograms.xml.
+enum DataReductionProxyNetworkChangeEvents {
+  // The client IP address changed.

[marq (ping after 24h), 2014/07/11 16:31:56]

Use a more vertically-compact formatting:

  
  IP_CHANGED = 0,  // The client IP address changed.
  DISABLED_ON_VPN = 1,   // The proxy is disabled because a VPN is running.
  CHANGE_EVENT_TYPE_MAX = 2  // This must always be last.

Also, the prevailing style in Chrome seems to be to name the last UMA enum value
<something>_COUNT, so CHANGE_EVENT_TYPE_COUNT here (or maybe
NETWORK_CHANGE_EVENT_COUNT, to match the UMA name).

[bengr, 2014/07/11 22:49:15]

Done.

+  IP_CHANGED = 0,
+
+  // The proxy is disabled because a VPN is running.
+  DISABLED_ON_VPN = 1,
+
+  // This must always be last.
+  CHANGE_EVENT_TYPE_MAX =2

[Ilya Sherman, 2014/07/11 03:45:52]

nit: Please add a space after the '=' sign.

[bengr, 2014/07/11 22:49:15]

Done.

+};
 
 // Key of the UMA DataReductionProxy.StartupState histogram.
 const char kUMAProxyStartupStateHistogram[] =
@@ -70,9 +84,11 @@ DataReductionProxySettings::DataReductionProxySettings(
     DataReductionProxyParams* params)
     : restricted_by_carrier_(false),
       enabled_by_user_(false),
+      disabled_on_vpn_(false),
       prefs_(NULL),
       local_state_prefs_(NULL),
-      url_request_context_getter_(NULL) {
+      url_request_context_getter_(NULL),
+      usage_stats_(NULL) {
   DCHECK(params);
   params_.reset(params);
 }
@@ -311,6 +327,11 @@ void DataReductionProxySettings::OnIPAddressChanged() {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (enabled_by_user_) {
     DCHECK(params_->allowed());
+    UMA_HISTOGRAM_ENUMERATION("DataReductionProxy.NetworkChangeEvents",
+                              IP_CHANGED,
+                              CHANGE_EVENT_TYPE_MAX);
+    if (DisableIfVPN())
+      return;
     ProbeWhetherDataReductionProxyIsAvailable();
     WarmProxyConnection();
   }
@@ -359,13 +380,13 @@ void DataReductionProxySettings::MaybeActivateDataReductionProxy(
 
   // Configure use of the data reduction proxy if it is enabled.
   enabled_by_user_= IsDataReductionProxyEnabled();
-  SetProxyConfigs(enabled_by_user_,
+  SetProxyConfigs(enabled_by_user_ && !disabled_on_vpn_,
                   IsDataReductionProxyAlternativeEnabled(),
                   restricted_by_carrier_,
                   at_startup);
 
   // Check if the proxy has been restricted explicitly by the carrier.
-  if (enabled_by_user_) {
+  if (enabled_by_user_ && !disabled_on_vpn_) {
     ProbeWhetherDataReductionProxyIsAvailable();
     WarmProxyConnection();
   }
@@ -425,6 +446,13 @@ void DataReductionProxySettings::RecordStartupState(ProxyStartupState state) {
                             PROXY_STARTUP_STATE_COUNT);
 }
 
+void DataReductionProxySettings::GetNetworkList(
+    net::NetworkInterfaceList* interfaces,
+    int policy) {
+  net::GetNetworkList(interfaces, policy);
+

[marq (ping after 24h), 2014/07/11 16:31:56]

Extra line.

[bengr, 2014/07/11 22:49:16]

Done.

+}
+
 void DataReductionProxySettings::ResetParamsForTest(
     DataReductionProxyParams* params) {
   params_.reset(params);
@@ -485,18 +513,6 @@ void DataReductionProxySettings::GetContentLengths(
       local_state->GetInt64(prefs::kDailyHttpContentLengthLastUpdateDate);
 }
 
-// static
-base::string16 DataReductionProxySettings::AuthHashForSalt(
-    int64 salt,
-    const std::string& key) {
-  std::string salted_key =
-      base::StringPrintf("%lld%s%lld",
-                         static_cast<long long>(salt),
-                         key.c_str(),
-                         static_cast<long long>(salt));
-  return base::UTF8ToUTF16(base::MD5String(salted_key));
-}
-
 net::URLFetcher* DataReductionProxySettings::GetBaseURLFetcher(
     const GURL& gurl,
     int load_flags) {
@@ -542,4 +558,29 @@ void DataReductionProxySettings::WarmProxyConnection() {
   warmup_fetcher_->Start();
 }
 
+bool DataReductionProxySettings::DisableIfVPN() {
+  net::NetworkInterfaceList network_interfaces;
+  GetNetworkList(&network_interfaces, 0);
+  const std::string vpn_interface_name_prefix = "tun";

[marq (ping after 24h), 2014/07/11 16:31:56]

Please add some comments explaining how this logic determines if the device is
on a VPN. What's the significance of "tun"?

Also, on what platforms is "tun" the interface prefix for the VPN?  If this
logic isn't supported on all platforms, appropriate comments should be made in
the header file.

[bengr, 2014/07/11 22:49:15]

I added a comment. This will work on all Unix-derived platforms. (We'll need to
verify on iOS.) When we port the proxy to Windows, we might need special logic.
I added a TODO.

+  for (size_t i = 0; i < network_interfaces.size(); ++i) {
+    std::string interface_name = network_interfaces[i].name;
+    if (LowerCaseEqualsASCII(
+        interface_name.begin(),
+        interface_name.begin() + vpn_interface_name_prefix.size(),
+        vpn_interface_name_prefix.c_str())) {
+      SetProxyConfigs(false,
+                      IsDataReductionProxyAlternativeEnabled(),
+                      false,
+                      false);
+      disabled_on_vpn_ = true;
+      UMA_HISTOGRAM_ENUMERATION("DataReductionProxy.NetworkChangeEvents",
+                                DISABLED_ON_VPN,
+                                CHANGE_EVENT_TYPE_MAX);

[Ilya Sherman, 2014/07/11 03:45:53]

nit: Please factor out a method for emitting to this histogram, so that there's
less chance that one of the codepaths will have a typo in it.

[marq (ping after 24h), 2014/07/11 16:31:56]

Or at least factor the UMA name into a constant.

[bengr, 2014/07/11 22:49:15]

Done.

[bengr, 2014/07/11 22:49:15]

Done.

+      return true;
+    }
+  }
+  disabled_on_vpn_ = false;
+  return false;
+}
+
 }  // namespace data_reduction_proxy