Fast-fail WPAD detection.

net/proxy/proxy_script_decider.h

Index: net/proxy/proxy_script_decider.h
diff --git a/net/proxy/proxy_script_decider.h b/net/proxy/proxy_script_decider.h
index 9a77938ec8e4aef834281184e16d1d55913b9b3c..941490215d726b880cc5c9449f4775781c12a8ed 100644
--- a/net/proxy/proxy_script_decider.h
+++ b/net/proxy/proxy_script_decider.h
@@ -12,9 +12,11 @@
 #include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
+#include "net/base/address_list.h"
 #include "net/base/completion_callback.h"
 #include "net/base/net_export.h"
 #include "net/base/net_log.h"
+#include "net/dns/host_resolver.h"
 #include "net/proxy/proxy_config.h"
 #include "net/proxy/proxy_resolver.h"
 #include "url/gurl.h"
@@ -103,12 +105,15 @@ class NET_EXPORT_PRIVATE ProxyScriptDecider {
 
   enum State {
     STATE_NONE,
+    STATE_QUICK_CHECK,
+    STATE_QUICK_CHECK_COMPLETE,
     STATE_WAIT,
     STATE_WAIT_COMPLETE,
     STATE_FETCH_PAC_SCRIPT,
     STATE_FETCH_PAC_SCRIPT_COMPLETE,
     STATE_VERIFY_PAC_SCRIPT,
     STATE_VERIFY_PAC_SCRIPT_COMPLETE,
+    STATE_FAILED,
   };
 
   // Returns ordered list of PAC urls to try for |config|.
@@ -118,6 +123,10 @@ class NET_EXPORT_PRIVATE ProxyScriptDecider {
   int DoLoop(int result);
   void DoCallback(int result);
 
+  int DoQuickCheck();
+  int DoQuickCheckComplete();
+  void OnQuickCheckComplete(int result);
+
   int DoWait();
   int DoWaitComplete(int result);
 
@@ -142,6 +151,7 @@ class NET_EXPORT_PRIVATE ProxyScriptDecider {
   // Returns the current PAC URL we are fetching/testing.
   const PacSource& current_pac_source() const;
 
+  void OnQuickCheckTimerFired();
   void OnWaitTimerFired();
   void DidComplete();
   void Cancel();
@@ -175,6 +185,12 @@ class NET_EXPORT_PRIVATE ProxyScriptDecider {
   ProxyConfig effective_config_;
   scoped_refptr<ProxyResolverScriptData> script_data_;
 
+  scoped_ptr<HostResolver> host_resolver_;
+  AddressList wpad_addrs_;
+  HostResolver::RequestHandle wpad_req_;
+  base::TimeDelta quick_check_delay_;

[szym, 2013/08/21 19:11:21]

Do you anticipate changing this value? If not, declare const int
kQuickCheckDelaySeconds in an anonymous namespace (in .cc) and construct
TimeDelta where you need it.

+  base::OneShotTimer<ProxyScriptDecider> quick_check_timer_;
+  base::Time quick_check_started_;

[szym, 2013/08/21 19:11:21]

Instead of storing it here, bind it into the Callback passed to the
|quick_check_timer_|.

[szym, 2013/08/21 19:21:09]

Both the timer and HostResolver::Request.

CompletionCallback callback = base::Bind(&...::OnQuickCheckComplete,
base::Unretained(this), base::Time::Now());

Resolve(..., callback);

timer_.Start(FROM_HERE, delay, base::Bind(callback, ERR_NAME_NOT_RESOLVED));

...::OnQuickCheckComplete(base::Time start_time, int result) {
  // compute TimeDelta, UMA result, OnIOComplete(result)
}

For this to work timer_ needs to be base::Timer(false, false).

 
   DISALLOW_COPY_AND_ASSIGN(ProxyScriptDecider);
 };