[net/dns] If the only name server is 0.0.0.0:53 assume DnsConfig is invalid.

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/dns_protocol.h"
 #include "net/dns/serial_worker.h"
 
 namespace net {
 
 namespace {
 
 #ifndef _PATH_RESCONF  // Normally defined in <resolv.h>
 #define _PATH_RESCONF "/etc/resolv.conf"
 #endif
 
@@ skipping 156 matching lines @@
   }
 
   dns_config->ndots = res.ndots;
   dns_config->timeout = base::TimeDelta::FromSeconds(res.retrans);
   dns_config->attempts = res.retry;
 #if defined(RES_ROTATE)
   dns_config->rotate = res.options & RES_ROTATE;
 #endif
   dns_config->edns0 = res.options & RES_USE_EDNS0;
 
+  // If the only name server is 0.0.0.0:53, assume the configuration is invalid.
+  const IPEndPoint kDefaultAddress(IPAddressNumber(kIPv4AddressSize),
+                                   dns_protocol::kDefaultPort);
+  if (dns_config->nameservers.size() == 1)
+    return !(dns_config->nameservers.front() == kDefaultAddress);

[mmenke, 2012/06/11 22:38:54]

Wonder if it makes more sense to fail if any of the entries are 0.0.0.0:53 (Or
0.0.0.0:X), since then we presumably wouldn't be behaving the same as
getaddrinfo.

[szym, 2012/06/14 16:18:20]

Done.

   return true;
 }
 #endif  // !defined(OS_ANDROID)
 
 }  // namespace internal
 
 // static
 scoped_ptr<DnsConfigService> DnsConfigService::CreateSystemService() {
   return scoped_ptr<DnsConfigService>(new internal::DnsConfigServicePosix());
 }
 
 }  // namespace net