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

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 1a8aa8962ffac5393f49848a33a0db768100ef46..4ed2e528e605feaff218533c261806f8023fad52 100644
--- a/net/base/net_util.cc
+++ b/net/base/net_util.cc
@@ -2111,6 +2111,46 @@ int GetPortFromSockaddr(const struct sockaddr* address, socklen_t address_len) {
   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: {

[wtc, 2011/03/25 19:06:24]

Thank you for considering the byte order issue.  We do need
to support both big endian and little endian machines.

IPAddressNumber is defined to be in network byte order.
struct in6_addr is also in network byte order.
(The IN6_ADDR macro is only available on Windows.)
So we can do a straight memcpy:
  struct in6_addr sin6_addr;
  memcpy(&sin6_addr, &ip_number[0], kIPv6AddressSize);
  return IN6_IS_ADDR_LOOPBACK(&sin6_addr);

Note: the copying to a struct in6_addr is necessary to
deal with alignment issue.

[Jói, 2011/03/25 21:26:51]

Done.

+        if (ip_number[15] != 1)
+          return false;
+
+        for (int i = 0; i < 15; ++i) {
+          if (ip_number[i] != 0)
+            return false;
+        }
+
+        return true;
+      }
+
+      default:
+        NOTREACHED();
+    }
+  }
+
+  return false;
+}
+
 NetworkInterface::NetworkInterface() {
 }