[NETD-BPF#1] Move libnetdutils to frameworks/libs/net/...

libnetdutils is referenced by netd.c and TrafficController.cpp, which
are going to be mainlined. Therefore, move libnetdutils to a common
place where both mainline module and platform code (Netd) can refer to.

Bug: 202086915
Test: build; flash; cd system/netd; atest
Ignore-AOSP-First: the netd change(same topic) would not automerge from
aosp.
No-Typo-Check: Clean code move with no other changes.
BYPASS_INCLUSIVE_LANGUAGE_REASON=Clean code move with no other changes.
Change-Id: I645bfe35f6543149c9a9f894cd4158d27a481abe
diff --git a/staticlibs/netd/libnetdutils/include/netdutils/Netlink.h b/staticlibs/netd/libnetdutils/include/netdutils/Netlink.h
new file mode 100644
index 0000000..ee5183a
--- /dev/null
+++ b/staticlibs/netd/libnetdutils/include/netdutils/Netlink.h
@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef NETUTILS_NETLINK_H
+#define NETUTILS_NETLINK_H
+
+#include <functional>
+#include <ostream>
+#include <linux/netlink.h>
+
+#include "netdutils/Slice.h"
+
+namespace android {
+namespace netdutils {
+
+// Invoke onMsg once for each netlink message in buf. onMsg will be
+// invoked with an aligned and deserialized header along with a Slice
+// containing the message payload.
+//
+// Assume that the first message begins at offset zero within buf.
+void forEachNetlinkMessage(const Slice buf,
+                           const std::function<void(const nlmsghdr&, const Slice)>& onMsg);
+
+// Invoke onAttr once for each netlink attribute in buf. onAttr will be
+// invoked with an aligned and deserialized header along with a Slice
+// containing the attribute payload.
+//
+// Assume that the first attribute begins at offset zero within buf.
+void forEachNetlinkAttribute(const Slice buf,
+                             const std::function<void(const nlattr&, const Slice)>& onAttr);
+
+}  // namespace netdutils
+}  // namespace android
+
+bool operator==(const sockaddr_nl& lhs, const sockaddr_nl& rhs);
+bool operator!=(const sockaddr_nl& lhs, const sockaddr_nl& rhs);
+
+std::ostream& operator<<(std::ostream& os, const nlmsghdr& hdr);
+std::ostream& operator<<(std::ostream& os, const nlattr& attr);
+std::ostream& operator<<(std::ostream& os, const sockaddr_nl& addr);
+
+#endif /* NETUTILS_NETLINK_H */