Add an opt-out header for HTTP throttling. Never throttle for localhost.

net/base/net_util.cc

 // 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.
 
 #include "net/base/net_util.h"
 
 #include <unicode/regex.h>
 #include <unicode/ucnv.h>
 #include <unicode/uidna.h>
 #include <unicode/ulocdata.h>
@@ skipping 2093 matching lines @@
   }
 }
 
 int GetPortFromSockaddr(const struct sockaddr* address, socklen_t address_len) {
   const uint16* port_field = GetPortFieldFromSockaddr(address, address_len);
   if (!port_field)
     return -1;
   return ntohs(*port_field);
 }
 
+bool IsLocalhost(const std::string& host) {
+  if (host == "localhost" ||
+      host == "localhost.localdomain" ||
+      host == "localhost6" ||
+      host == "localhost6.localdomain6")
+    return true;
+
+  IPAddressNumber ip_number;
+  if (ParseIPLiteralToNumber(host, &ip_number)) {
+    size_t size = ip_number.size();
+    switch (size) {
+      case kIPv4AddressSize: {
+        IPAddressNumber localhost_prefix;
+        localhost_prefix.push_back(127);
+        for (int i = 0; i < 3; ++i) {
+          localhost_prefix.push_back(0);
+        }
+        return IPNumberMatchesPrefix(ip_number, localhost_prefix, 8);
+      }
+
+      case kIPv6AddressSize: {
+        struct in6_addr sin6_addr;
+        memcpy(&sin6_addr, &ip_number[0], kIPv6AddressSize);
+        return IN6_IS_ADDR_LOOPBACK(&sin6_addr) != FALSE;

[wtc, 2011/03/28 22:08:19]

The != FALSE part should be unnecessary.  I know why you
added it.  I've seen Chromium code that uses !! for this
purpose:
    return !!IN6_IS_ADDR_LOOPBACK(&sin6_addr);
which we should use only as a last resort.

Also, FALSE may not be defined on non-Windows platforms.

+      }
+
+      default:
+        NOTREACHED();
+    }
+  }
+
+  return false;
+}
+
 NetworkInterface::NetworkInterface() {
 }
 
 NetworkInterface::NetworkInterface(const std::string& name,
                                    const IPAddressNumber& address)
     : name(name), address(address) {
 }
 
 NetworkInterface::~NetworkInterface() {
 }
 
 }  // namespace net