[net/dns] Watch configd notifications to detect DnsConfig changes on Mac.

net/dns/dns_config_service_posix.cc

Index: net/dns/dns_config_service_posix.cc
diff --git a/net/dns/dns_config_service_posix.cc b/net/dns/dns_config_service_posix.cc
index b3977fceca0ed6112ce0e391d2cbb8f7af2a007a..e6550121aab62290d03028139b80f47285a7e682 100644
--- a/net/dns/dns_config_service_posix.cc
+++ b/net/dns/dns_config_service_posix.cc
@@ -16,6 +16,10 @@
 #include "net/dns/file_path_watcher_wrapper.h"
 #include "net/dns/serial_worker.h"
 
+#if defined(OS_MACOSX)
+#include "net/dns/notify_watcher_mac.h"
+#endif
+
 #ifndef _PATH_RESCONF  // Normally defined in <resolv.h>
 #define _PATH_RESCONF "/etc/resolv.conf"
 #endif
@@ -85,6 +89,9 @@ namespace internal {
 DnsConfigServicePosix::DnsConfigServicePosix()
     : config_watcher_(new FilePathWatcherWrapper()),
       hosts_watcher_(new FilePathWatcherWrapper()) {
+#if defined(OS_MACOSX)
+  notify_watcher_.reset(new NotifyWatcherMac());
+#endif
   config_reader_ = new ConfigReader(
       base::Bind(&DnsConfigServicePosix::OnConfigRead,
                  base::Unretained(this)));
@@ -104,11 +111,21 @@ void DnsConfigServicePosix::Watch(const CallbackType& callback) {
   DCHECK(!callback.is_null());
   set_callback(callback);
 
+  base::Callback<void(bool succeeded)> config_callback =
+      base::Bind(&DnsConfigServicePosix::OnConfigChanged,
+                 base::Unretained(this));
+
   // Even if watchers fail, we keep the other one as it provides useful signals.
-  if (config_watcher_->Watch(
-         FilePath(kFilePathConfig),
-         base::Bind(&DnsConfigServicePosix::OnConfigChanged,
-                    base::Unretained(this)))) {
+#if defined(OS_MACOSX)
+  // TODO(szym): Use dns_configuration_notify_key() from dnsinfo.h?

[Mark Mentovai, 2012/04/17 16:27:43]

Yes. Don’t hard-code.

(Unless you have a good reason to, in which case the comment should say what the
good reason is.)

[szym, 2012/04/17 19:39:31]

#include <dnsinfo.h> does not work on my Mac. It seems there is no dnsinfo.h on
my Mac at all. Wasn't sure if importing this constant warrants a third_party
dep.

[Mark Mentovai, 2012/04/17 19:47:39]

szym wrote:
I see. I don’t have that header either.

Where’d you find dnsinfo.h and dns_configuration_notify_key(), then? Just by
poking around in the configd project?

+  // TODO(szym): Remove |config_watcher_| and use |notify_watcher_| exclusively.

[Mark Mentovai, 2012/04/17 16:27:43]

…implying that both should just be different implementations of the same
interface?

[szym, 2012/04/17 19:39:31]

That makes sense. I'm quite confident NotifyWatcherMac is sufficient and there's
no need for FilePathWatcher on resolv.conf so I'll unify the interfaces.

+  const char* kDnsNotifyKey = "com.apple.system.SystemConfiguration."
+  "dns_configuration";

[Mark Mentovai, 2012/04/17 16:27:43]

If you were keeping this, which you aren’t, it’d be preferable to not break up
the string like this, since the whole thing would fit on one line. The
continuation line would be bumped over by a 4-space indent. But you’re not
keeping this, because you’re using dns_configuration_notify_key().

+  if (notify_watcher_->Watch(kDnsNotifyKey, config_callback) &&
+      config_watcher_->Watch(FilePath(kFilePathConfig), config_callback)) {
+#else
+  if (config_watcher_->Watch(FilePath(kFilePathConfig), config_callback)) {
+#endif
     OnConfigChanged(true);
   } else {
     OnConfigChanged(false);