Allow hyphens at the beginning of domain components, except for the last domain component.

net/base/net_util.h

 // Copyright (c) 2011 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.
 
 #ifndef NET_BASE_NET_UTIL_H_
 #define NET_BASE_NET_UTIL_H_
 #pragma once
 
 #include "build/build_config.h"
 
@@ skipping 188 matching lines @@
 
 // Canonicalizes |host| and returns it.  Also fills |host_info| with
 // IP address information.  |host_info| must not be NULL.
 NET_API std::string CanonicalizeHost(const std::string& host,
                                      url_canon::CanonHostInfo* host_info);
 
 // Returns true if |host| is not an IP address and is compliant with a set of
 // rules based on RFC 1738 and tweaked to be compatible with the real world.
 // The rules are:
 //   * One or more components separated by '.'
-//   * Each component begins and ends with an alphanumeric character
+//   * Each component begins with an alphanumeric character or '-'
 //   * Each component contains only alphanumeric characters and '-' or '_'
-//   * The last component does not begin with a digit
+//   * Each component ends with an alphanumeric character
+//   * The last component begins with an alphabetic character
 //   * Optional trailing dot after last component (means "treat as FQDN")
 // If |desired_tld| is non-NULL, the host will only be considered invalid if
 // appending it as a trailing component still results in an invalid host.  This
 // helps us avoid marking as "invalid" user attempts to open "www.401k.com" by
 // typing 4-0-1-k-<ctrl>+<enter>.
 //
 // NOTE: You should only pass in hosts that have been returned from
 // CanonicalizeHost(), or you may not get accurate results.
 NET_API bool IsCanonicalizedHostCompliant(const std::string& host,
                                           const std::string& desired_tld);
@@ skipping 235 matching lines @@
 
 // Returns list of network interfaces except loopback interface. If an
 // interface has more than one address, a separate entry is added to
 // the list for each address.
 // Can be called only on a thread that allows IO.
 NET_API bool GetNetworkList(NetworkInterfaceList* networks);
 
 }  // namespace net
 
 #endif  // NET_BASE_NET_UTIL_H_