Relocate KeepalivePacketData to frameworks/base

Due to an issue resolving the boot classpath, the
KeepalivePacketData structure cannot be referenced
by frameworks/opt/telephony while it is in services.

-Move KeepalivePacketData to android.net
-Also, relocate IpUtils without changing the package
 name.

Bug: 38350389
Test: compilation
Change-Id: If5fc63e9ad8b9b2d4c2fee47ff4bab2ab190a05a
(cherry picked from commit bd4093be7cab51d6ad031854324134a9c8637c2c)

core/java/android/net/KeepalivePacketData.java

@@ -0,0 +1,137 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+package android.net;
+
+import static android.net.util.NetworkConstants.IPV4_HEADER_MIN_LEN;
+import static android.net.util.NetworkConstants.UDP_HEADER_LEN;
+
+import android.system.OsConstants;
+import android.net.ConnectivityManager;
+import android.net.NetworkUtils;
+import android.net.util.IpUtils;
+
+import java.net.Inet4Address;
+import java.net.Inet6Address;
+import java.net.InetAddress;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+
+import static android.net.ConnectivityManager.PacketKeepalive.*;
+
+/**
+ * Represents the actual packets that are sent by the
+ * {@link android.net.ConnectivityManager.PacketKeepalive} API.
+ *
+ * @hide
+ */
+public class KeepalivePacketData {
+    /** Protocol of the packet to send; one of the OsConstants.ETH_P_* values. */
+    public final int protocol;
+
+    /** Source IP address */
+    public final InetAddress srcAddress;
+
+    /** Destination IP address */
+    public final InetAddress dstAddress;
+
+    /** Source port */
+    public final int srcPort;
+
+    /** Destination port */
+    public final int dstPort;
+
+    /** Destination MAC address. Can change if routing changes. */
+    public byte[] dstMac;
+
+    /** Packet data. A raw byte string of packet data, not including the link-layer header. */
+    public final byte[] data;
+
+    protected KeepalivePacketData(InetAddress srcAddress, int srcPort,
+            InetAddress dstAddress, int dstPort, byte[] data) throws InvalidPacketException {
+        this.srcAddress = srcAddress;
+        this.dstAddress = dstAddress;
+        this.srcPort = srcPort;
+        this.dstPort = dstPort;
+        this.data = data;
+
+        // Check we have two IP addresses of the same family.
+        if (srcAddress == null || dstAddress == null ||
+                !srcAddress.getClass().getName().equals(dstAddress.getClass().getName())) {
+            throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS);
+        }
+
+        // Set the protocol.
+        if (this.dstAddress instanceof Inet4Address) {
+            this.protocol = OsConstants.ETH_P_IP;
+        } else if (this.dstAddress instanceof Inet6Address) {
+            this.protocol = OsConstants.ETH_P_IPV6;
+        } else {
+            throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS);
+        }
+
+        // Check the ports.
+        if (!IpUtils.isValidUdpOrTcpPort(srcPort) || !IpUtils.isValidUdpOrTcpPort(dstPort)) {
+            throw new InvalidPacketException(ERROR_INVALID_PORT);
+        }
+    }
+
+    public static class InvalidPacketException extends Exception {
+        final public int error;
+        public InvalidPacketException(int error) {
+            this.error = error;
+        }
+    }
+
+    /**
+     * Creates an IPsec NAT-T keepalive packet with the specified parameters.
+     */
+    public static KeepalivePacketData nattKeepalivePacket(
+            InetAddress srcAddress, int srcPort,
+            InetAddress dstAddress, int dstPort) throws InvalidPacketException {
+
+        if (!(srcAddress instanceof Inet4Address) || !(dstAddress instanceof Inet4Address)) {
+            throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS);
+        }
+
+        if (dstPort != NATT_PORT) {
+            throw new InvalidPacketException(ERROR_INVALID_PORT);
+        }
+
+        int length = IPV4_HEADER_MIN_LEN + UDP_HEADER_LEN + 1;
+        ByteBuffer buf = ByteBuffer.allocate(length);
+        buf.order(ByteOrder.BIG_ENDIAN);
+        buf.putShort((short) 0x4500);             // IP version and TOS
+        buf.putShort((short) length);
+        buf.putInt(0);                            // ID, flags, offset
+        buf.put((byte) 64);                       // TTL
+        buf.put((byte) OsConstants.IPPROTO_UDP);
+        int ipChecksumOffset = buf.position();
+        buf.putShort((short) 0);                  // IP checksum
+        buf.put(srcAddress.getAddress());
+        buf.put(dstAddress.getAddress());
+        buf.putShort((short) srcPort);
+        buf.putShort((short) dstPort);
+        buf.putShort((short) (length - 20));      // UDP length
+        int udpChecksumOffset = buf.position();
+        buf.putShort((short) 0);                  // UDP checksum
+        buf.put((byte) 0xff);                     // NAT-T keepalive
+        buf.putShort(ipChecksumOffset, IpUtils.ipChecksum(buf, 0));
+        buf.putShort(udpChecksumOffset, IpUtils.udpChecksum(buf, 0, IPV4_HEADER_MIN_LEN));
+
+        return new KeepalivePacketData(srcAddress, srcPort, dstAddress, dstPort, buf.array());
+    }
+}