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

net/dns/dns_config_service_posix.cc

 // Copyright (c) 2012 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/dns/dns_config_service_posix.h"
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "net/base/ip_endpoint.h"
 #include "net/base/net_util.h"
 #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
 
 namespace net {
 
 namespace {
 
 const FilePath::CharType* kFilePathConfig = FILE_PATH_LITERAL(_PATH_RESCONF);
 const FilePath::CharType* kFilePathHosts = FILE_PATH_LITERAL("/etc/hosts");
@@ skipping 49 matching lines @@
   bool success_;
 };
 
 }  // namespace
 
 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)));
   hosts_reader_ = new DnsHostsReader(
       FilePath(kFilePathHosts),
       base::Bind(&DnsConfigServicePosix::OnHostsRead,
                  base::Unretained(this)));
 }
 
 DnsConfigServicePosix::~DnsConfigServicePosix() {
   config_reader_->Cancel();
   hosts_reader_->Cancel();
 }
 
 void DnsConfigServicePosix::Watch(const CallbackType& callback) {
   DCHECK(CalledOnValidThread());
   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);
   }
 
   if (hosts_watcher_->Watch(
          FilePath(kFilePathHosts),
          base::Bind(&DnsConfigServicePosix::OnHostsChanged,
                     base::Unretained(this)))) {
     OnHostsChanged(true);
@@ skipping 77 matching lines @@
 #endif  // !defined(OS_ANDROID)
 
 }  // namespace internal
 
 // static
 scoped_ptr<DnsConfigService> DnsConfigService::CreateSystemService() {
   return scoped_ptr<DnsConfigService>(new internal::DnsConfigServicePosix());
 }
 
 }  // namespace net