[net/dns] Resolve AF_UNSPEC on dual-stacked systems. Sort addresses according to RFC3484.

net/base/net_util.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/base/net_util.h"
 
 #include <algorithm>
 #include <iterator>
 #include <map>
 
@@ skipping 2198 matching lines @@
 
   // Otherwise the string is an IPv4 address.
   ip_number->resize(4);  // 32 bits.
   url_parse::Component host_comp(0, ip_literal.size());
   int num_components;
   url_canon::CanonHostInfo::Family family = url_canon::IPv4AddressToNumber(
       ip_literal.data(), host_comp, &(*ip_number)[0], &num_components);
   return family == url_canon::CanonHostInfo::IPV4;
 }
 
+namespace {
+
+const unsigned char kIPv4MappedPrefix[] =
+    { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF };
+}
+
 IPAddressNumber ConvertIPv4NumberToIPv6Number(
     const IPAddressNumber& ipv4_number) {
   DCHECK(ipv4_number.size() == 4);
 
   // IPv4-mapped addresses are formed by:
   // <80 bits of zeros>  + <16 bits of ones> + <32-bit IPv4 address>.
   IPAddressNumber ipv6_number;
   ipv6_number.reserve(16);
-  ipv6_number.insert(ipv6_number.end(), 10, 0);
-  ipv6_number.push_back(0xFF);
-  ipv6_number.push_back(0xFF);
+  ipv6_number.insert(ipv6_number.end(),
+                     kIPv4MappedPrefix,
+                     kIPv4MappedPrefix + arraysize(kIPv4MappedPrefix));
   ipv6_number.insert(ipv6_number.end(), ipv4_number.begin(), ipv4_number.end());
   return ipv6_number;
 }
 
+bool IsIPv4Mapped(const IPAddressNumber& address) {
+  if (address.size() != kIPv6AddressSize)
+    return false;
+  return std::equal(address.begin(),
+                    address.begin() + arraysize(kIPv4MappedPrefix),
+                    kIPv4MappedPrefix);
+}
+
+IPAddressNumber ConvertIPv4MappedToIPv4(const IPAddressNumber& address) {
+  DCHECK(IsIPv4Mapped(address));
+  return IPAddressNumber(address.begin() + arraysize(kIPv4MappedPrefix),
+                         address.end());
+}
+
 bool ParseCIDRBlock(const std::string& cidr_literal,
                     IPAddressNumber* ip_number,
                     size_t* prefix_length_in_bits) {
   // We expect CIDR notation to match one of these two templates:
   //   <IPv4-literal> "/" <number of bits>
   //   <IPv6-literal> "/" <number of bits>
 
   std::vector<std::string> parts;
   base::SplitString(cidr_literal, '/', &parts);
   if (parts.size() != 2)
@@ skipping 124 matching lines @@
 
 NetworkInterface::NetworkInterface(const std::string& name,
                                    const IPAddressNumber& address)
     : name(name), address(address) {
 }
 
 NetworkInterface::~NetworkInterface() {
 }
 
 }  // namespace net