Fast path for google_util::IsValidHostName

components/google/core/browser/google_util.cc

 // Copyright 2014 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 "components/google/core/browser/google_util.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <vector>
@@ skipping 32 matching lines @@
 bool IsPathHomePageBase(base::StringPiece path) {
   return (path == "/") || (path == "/webhp");
 }
 
 // True if the given canonical |host| is "[www.]<domain_in_lower_case>.<TLD>"
 // with a valid TLD. If |subdomain_permission| is ALLOW_SUBDOMAIN, we check
 // against host "*.<domain_in_lower_case>.<TLD>" instead.
 bool IsValidHostName(base::StringPiece host,
                      base::StringPiece domain_in_lower_case,
                      SubdomainPermission subdomain_permission) {
+  // Fast path to avoid searching the registry set.
+  if (host.find(domain_in_lower_case) == base::StringPiece::npos)
+    return false;
   size_t tld_length =
       net::registry_controlled_domains::GetCanonicalHostRegistryLength(
           host, net::registry_controlled_domains::EXCLUDE_UNKNOWN_REGISTRIES,
           net::registry_controlled_domains::EXCLUDE_PRIVATE_REGISTRIES);
   if ((tld_length == 0) || (tld_length == std::string::npos))
     return false;
 
   // Removes the tld and the preceding dot.
   base::StringPiece host_minus_tld =
       host.substr(0, host.length() - tld_length - 1);
@@ skipping 164 matching lines @@
 }
 
 bool IsYoutubeDomainUrl(const GURL& url,
                         SubdomainPermission subdomain_permission,
                         PortPermission port_permission) {
   return IsValidURL(url, port_permission) &&
       IsValidHostName(url.host_piece(), "youtube", subdomain_permission);
 }
 
 }  // namespace google_util