shill: Add IPAddress class

Add class that holds IP Addresses.  Routing will need these.
Move address family constants out of IPConfig to this new class.

BUG=chromium-os:17277
TEST=New unittest

Change-Id: I69d9c4d551061de890ed6919462597a15ae51857
Reviewed-on: http://gerrit.chromium.org/gerrit/4180
Reviewed-by: Darin Petkov <petkov@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
diff --git a/ip_address.cc b/ip_address.cc
new file mode 100644
index 0000000..9d300bd
--- /dev/null
+++ b/ip_address.cc
@@ -0,0 +1,54 @@
+// Copyright (c) 2011 The Chromium OS 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 "shill/ip_address.h"
+
+#include <netinet/in.h>
+
+#include <string>
+
+#include "shill/byte_string.h"
+
+namespace shill {
+
+IPAddress::IPAddress(Family family, const ByteString &address)
+    : family_(family) ,
+      address_(address) {}
+
+IPAddress::IPAddress(Family family)
+    : family_(family) {}
+
+IPAddress::~IPAddress() {}
+
+int IPAddress::GetAddressLength(Family family) {
+  switch (family) {
+  case kAddressFamilyIPv4:
+    return sizeof(in_addr);
+  case kAddressFamilyIPv6:
+    return sizeof(in6_addr);
+  default:
+    return 0;
+  }
+}
+
+bool IPAddress::SetAddressFromString(const std::string &address_string) {
+  int address_length = GetAddressLength(family_);
+
+  if (!address_length) {
+    return false;
+  }
+
+  ByteString address(address_length);
+  if (inet_pton(family_, address_string.c_str(), address.GetData()) <= 0) {
+    return false;
+  }
+  address_ = address;
+  return true;
+}
+
+void IPAddress::SetAddressToDefault() {
+  address_ = ByteString(GetAddressLength(family_));
+}
+
+}  // namespace shill