Implement NetworkChangeNotifier::IsCurrentlyOffline() for Mac.

net/base/network_change_notifier_mac.cc

-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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/base/network_change_notifier_mac.h"
 
+#include <netinet/in.h>
 #include <SystemConfiguration/SCDynamicStoreKey.h>
+#include <SystemConfiguration/SCNetworkReachability.h>
 #include <SystemConfiguration/SCSchemaDefinitions.h>
 
 #include "base/mac/scoped_cftyperef.h"
 
 namespace net {
 
 NetworkChangeNotifierMac::NetworkChangeNotifierMac()
     : forwarder_(this),
-      config_watcher_(&forwarder_) {}
-NetworkChangeNotifierMac::~NetworkChangeNotifierMac() {}
+      config_watcher_(&forwarder_),
+      network_reachable_(true) {}
+
+NetworkChangeNotifierMac::~NetworkChangeNotifierMac() {
+  if (reachability_.get() && run_loop_.get()) {
+    SCNetworkReachabilityUnscheduleFromRunLoop(reachability_.get(),
+                                               run_loop_.get(),
+                                               kCFRunLoopCommonModes);
+  }
+}
 
 bool NetworkChangeNotifierMac::IsCurrentlyOffline() const {
-  // TODO(eroman): http://crbug.com/53473
-  return false;
+  return !network_reachable_;
 }
 
 void NetworkChangeNotifierMac::SetDynamicStoreNotificationKeys(
     SCDynamicStoreRef store) {
   // Called on notifier thread.
+  run_loop_.reset(CFRunLoopGetCurrent());
+  CFRetain(run_loop_.get());
+
   base::mac::ScopedCFTypeRef<CFMutableArrayRef> notification_keys(
       CFArrayCreateMutable(kCFAllocatorDefault, 0, &kCFTypeArrayCallBacks));
   base::mac::ScopedCFTypeRef<CFStringRef> key(
       SCDynamicStoreKeyCreateNetworkGlobalEntity(
           NULL, kSCDynamicStoreDomainState, kSCEntNetInterface));
   CFArrayAppendValue(notification_keys.get(), key.get());
   key.reset(SCDynamicStoreKeyCreateNetworkGlobalEntity(
       NULL, kSCDynamicStoreDomainState, kSCEntNetIPv4));
   CFArrayAppendValue(notification_keys.get(), key.get());
   key.reset(SCDynamicStoreKeyCreateNetworkGlobalEntity(
       NULL, kSCDynamicStoreDomainState, kSCEntNetIPv6));
   CFArrayAppendValue(notification_keys.get(), key.get());
 
   // Set the notification keys.  This starts us receiving notifications.
   bool ret = SCDynamicStoreSetNotificationKeys(
       store, notification_keys.get(), NULL);
   // TODO(willchan): Figure out a proper way to handle this rather than crash.
   CHECK(ret);
+
+  // Try to reach 0.0.0.0. This is the approach taken by Firefox:
+  //
+  // http://mxr.mozilla.org/mozilla2.0/source/netwerk/system/mac/nsNetworkLinkService.mm
+  //
+  // From my (adamk) testing on Snow Leopard, 0.0.0.0
+  // seems to be reachable if any network connection is available.
+  struct sockaddr_in addr = {0};
+  addr.sin_len = sizeof(addr);
+  addr.sin_family = AF_INET;
+  reachability_.reset(SCNetworkReachabilityCreateWithAddress(
+      kCFAllocatorDefault, reinterpret_cast<struct sockaddr*>(&addr)));
+  SCNetworkReachabilityContext reachability_context = {
+    0,     // version
+    this,  // user data
+    NULL,  // retain
+    NULL,  // release
+    NULL   // description
+  };
+  if (!SCNetworkReachabilitySetCallback(
+          reachability_.get(),
+          &NetworkChangeNotifierMac::ReachabilityCallback,
+          &reachability_context)) {
+    LOG(DFATAL) << "Could not set network reachability callback";
+    reachability_.reset();
+  } else if (!SCNetworkReachabilityScheduleWithRunLoop(reachability_.get(),
+                                                       run_loop_,
+                                                       kCFRunLoopCommonModes)) {
+    LOG(DFATAL) << "Could not schedule network reachability on run loop";
+    reachability_.reset();
+  }
 }
 
 void NetworkChangeNotifierMac::OnNetworkConfigChange(CFArrayRef changed_keys) {
-  // Called on notifier thread.
+  DCHECK_EQ(run_loop_.get(), CFRunLoopGetCurrent());
 
   for (CFIndex i = 0; i < CFArrayGetCount(changed_keys); ++i) {
     CFStringRef key = static_cast<CFStringRef>(
         CFArrayGetValueAtIndex(changed_keys, i));
     if (CFStringHasSuffix(key, kSCEntNetIPv4) ||
         CFStringHasSuffix(key, kSCEntNetIPv6)) {
       NotifyObserversOfIPAddressChange();
       return;
     }
     if (CFStringHasSuffix(key, kSCEntNetInterface)) {
       // TODO(willchan): Does not appear to be working.  Look into this.
       // Perhaps this isn't needed anyway.
     } else {
       NOTREACHED();
     }
   }
 }
 
+// static
+void NetworkChangeNotifierMac::ReachabilityCallback(
+    SCNetworkReachabilityRef target,
+    SCNetworkConnectionFlags flags,
+    void* notifier) {
+  NetworkChangeNotifierMac* notifier_mac =
+      static_cast<NetworkChangeNotifierMac*>(notifier);
+
+  DCHECK_EQ(notifier_mac->run_loop_.get(), CFRunLoopGetCurrent());
+
+  bool reachable = flags & kSCNetworkFlagsReachable;
+  bool connection_required = flags & kSCNetworkFlagsConnectionRequired;
+  bool old_reachability = notifier_mac->network_reachable_;
+  notifier_mac->network_reachable_ = reachable && !connection_required;
+  if (old_reachability != notifier_mac->network_reachable_)
+    notifier_mac->NotifyObserversOfOnlineStateChange();
+}
+
 }  // namespace net