Always treat .localhost as loopback

net/base/net_util.cc

Index: net/base/net_util.cc
diff --git a/net/base/net_util.cc b/net/base/net_util.cc
index 3b49dffb5c20d889003a09755276ddaa8e41542d..c893e6164d0301196d9dcff4709bd977baa4a130 100644
--- a/net/base/net_util.cc
+++ b/net/base/net_util.cc
@@ -981,10 +981,9 @@ int GetPortFromSockaddr(const struct sockaddr* address, socklen_t address_len) {
 }
 
 bool IsLocalhost(const std::string& host) {
-  if (host == "localhost" ||
-      host == "localhost.localdomain" ||
-      host == "localhost6" ||
-      host == "localhost6.localdomain6")
+  if (host == "localhost" || host == "localhost.localdomain" ||
+      host == "localhost6" || host == "localhost6.localdomain6" ||
+      IsLocalhostTLD(host))
     return true;
 
   IPAddressNumber ip_number;
@@ -1014,6 +1013,24 @@ bool IsLocalhost(const std::string& host) {
   return false;
 }
 
+bool IsLocalhostTLD(const std::string& host) {
+  const char kLocalhostTLD[] = ".localhost";
+  const size_t kLocalhostTLDLength = arraysize(kLocalhostTLD) - 1;
+
+  if (host.empty())
+    return false;
+
+  size_t host_len = host.size();
+  if (*host.rbegin() == '.')

[Deprecated (see juliatuttle), 2015/03/26 17:04:36]

Nit: host.back()? I think we're using C++11 now, so it should be okay.

[Ryan Sleevi, 2015/03/26 17:10:56]

language, not library, so rbegin is needed

+    --host_len;
+  if (host_len < kLocalhostTLDLength)
+    return false;
+
+  const char* host_suffix = host.data() + host_len - kLocalhostTLDLength;
+  return base::strncasecmp(host_suffix, kLocalhostTLD, kLocalhostTLDLength) ==
+         0;
+}
+
 NetworkInterface::NetworkInterface()
     : type(NetworkChangeNotifier::CONNECTION_UNKNOWN), prefix_length(0) {
 }