Add TcpKeepalivePacketData to SystemApi

This is consistent with NattKeepalivePacketData, which is also a
subclass of KeepalivePacketData.

TcpKeepalivePacketData is already used by the wifi module, but
statically linked.

Bug: 172789687
Test: m
Change-Id: I6aee1ae205987521bea4a3838bbece279ffa0e37

9 files changed, 425 insertions, 285 deletions

diff --git a/core/api/system-current.txt b/core/api/system-current.txt
index a48ad95ea40e..3980774468ab 100644
--- a/core/api/system-current.txt
+++ b/core/api/system-current.txt
@@ -6400,6 +6400,19 @@ package android.net {
     method @NonNull public android.net.StaticIpConfiguration.Builder setIpAddress(@Nullable android.net.LinkAddress);
   }
 
+  public final class TcpKeepalivePacketData extends android.net.KeepalivePacketData implements android.os.Parcelable {
+    ctor public TcpKeepalivePacketData(@NonNull java.net.InetAddress, int, @NonNull java.net.InetAddress, int, @NonNull byte[], int, int, int, int, int, int) throws android.net.InvalidPacketException;
+    method public int describeContents();
+    method public void writeToParcel(@NonNull android.os.Parcel, int);
+    field @NonNull public static final android.os.Parcelable.Creator<android.net.TcpKeepalivePacketData> CREATOR;
+    field public final int ipTos;
+    field public final int ipTtl;
+    field public final int tcpAck;
+    field public final int tcpSeq;
+    field public final int tcpWindow;
+    field public final int tcpWindowScale;
+  }
+
   public class TrafficStats {
     method public static void setThreadStatsTagApp();
     method public static void setThreadStatsTagBackup();
diff --git a/core/java/android/net/TcpKeepalivePacketData.java b/core/java/android/net/TcpKeepalivePacketData.java
new file mode 100644
index 000000000000..ddb3a6a72fb4
--- /dev/null
+++ b/core/java/android/net/TcpKeepalivePacketData.java
@@ -0,0 +1,163 @@
+/*
+ * Copyright (C) 2020 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 android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.annotation.SystemApi;
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import java.net.InetAddress;
+import java.util.Objects;
+
+/**
+ * Represents the actual tcp keep alive packets which will be used for hardware offload.
+ * @hide
+ */
+@SystemApi
+public final class TcpKeepalivePacketData extends KeepalivePacketData implements Parcelable {
+    private static final String TAG = "TcpKeepalivePacketData";
+
+    /** TCP sequence number. */
+    public final int tcpSeq;
+
+    /** TCP ACK number. */
+    public final int tcpAck;
+
+    /** TCP RCV window. */
+    public final int tcpWindow;
+
+    /** TCP RCV window scale. */
+    public final int tcpWindowScale;
+
+    /** IP TOS. */
+    public final int ipTos;
+
+    /** IP TTL. */
+    public final int ipTtl;
+
+    public TcpKeepalivePacketData(@NonNull final InetAddress srcAddress, int srcPort,
+            @NonNull final InetAddress dstAddress, int dstPort, @NonNull final byte[] data,
+            int tcpSeq, int tcpAck, int tcpWindow, int tcpWindowScale, int ipTos, int ipTtl)
+            throws InvalidPacketException {
+        super(srcAddress, srcPort, dstAddress, dstPort, data);
+        this.tcpSeq = tcpSeq;
+        this.tcpAck = tcpAck;
+        this.tcpWindow = tcpWindow;
+        this.tcpWindowScale = tcpWindowScale;
+        this.ipTos = ipTos;
+        this.ipTtl = ipTtl;
+    }
+
+    @Override
+    public boolean equals(@Nullable final Object o) {
+        if (!(o instanceof TcpKeepalivePacketData)) return false;
+        final TcpKeepalivePacketData other = (TcpKeepalivePacketData) o;
+        final InetAddress srcAddress = getSrcAddress();
+        final InetAddress dstAddress = getDstAddress();
+        return srcAddress.equals(other.getSrcAddress())
+                && dstAddress.equals(other.getDstAddress())
+                && getSrcPort() == other.getSrcPort()
+                && getDstPort() == other.getDstPort()
+                && this.tcpAck == other.tcpAck
+                && this.tcpSeq == other.tcpSeq
+                && this.tcpWindow == other.tcpWindow
+                && this.tcpWindowScale == other.tcpWindowScale
+                && this.ipTos == other.ipTos
+                && this.ipTtl == other.ipTtl;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(getSrcAddress(), getDstAddress(), getSrcPort(), getDstPort(),
+                tcpAck, tcpSeq, tcpWindow, tcpWindowScale, ipTos, ipTtl);
+    }
+
+    /**
+     * Parcelable Implementation.
+     * Note that this object implements parcelable (and needs to keep doing this as it inherits
+     * from a class that does), but should usually be parceled as a stable parcelable using
+     * the toStableParcelable() and fromStableParcelable() methods.
+     */
+    @Override
+    public int describeContents() {
+        return 0;
+    }
+
+    /** Write to parcel. */
+    @Override
+    public void writeToParcel(@NonNull Parcel out, int flags) {
+        out.writeString(getSrcAddress().getHostAddress());
+        out.writeString(getDstAddress().getHostAddress());
+        out.writeInt(getSrcPort());
+        out.writeInt(getDstPort());
+        out.writeByteArray(getPacket());
+        out.writeInt(tcpSeq);
+        out.writeInt(tcpAck);
+        out.writeInt(tcpWindow);
+        out.writeInt(tcpWindowScale);
+        out.writeInt(ipTos);
+        out.writeInt(ipTtl);
+    }
+
+    private static TcpKeepalivePacketData readFromParcel(Parcel in) throws InvalidPacketException {
+        InetAddress srcAddress = InetAddresses.parseNumericAddress(in.readString());
+        InetAddress dstAddress = InetAddresses.parseNumericAddress(in.readString());
+        int srcPort = in.readInt();
+        int dstPort = in.readInt();
+        byte[] packet = in.createByteArray();
+        int tcpSeq = in.readInt();
+        int tcpAck = in.readInt();
+        int tcpWnd = in.readInt();
+        int tcpWndScale = in.readInt();
+        int ipTos = in.readInt();
+        int ipTtl = in.readInt();
+        return new TcpKeepalivePacketData(srcAddress, srcPort, dstAddress, dstPort, packet, tcpSeq,
+                tcpAck, tcpWnd, tcpWndScale, ipTos, ipTtl);
+    }
+
+    /** Parcelable Creator. */
+    public static final @NonNull Parcelable.Creator<TcpKeepalivePacketData> CREATOR =
+            new Parcelable.Creator<TcpKeepalivePacketData>() {
+                public TcpKeepalivePacketData createFromParcel(Parcel in) {
+                    try {
+                        return readFromParcel(in);
+                    } catch (InvalidPacketException e) {
+                        throw new IllegalArgumentException(
+                                "Invalid TCP keepalive data: " + e.getError());
+                    }
+                }
+
+                public TcpKeepalivePacketData[] newArray(int size) {
+                    return new TcpKeepalivePacketData[size];
+                }
+            };
+
+    @Override
+    public String toString() {
+        return "saddr: " + getSrcAddress()
+                + " daddr: " + getDstAddress()
+                + " sport: " + getSrcPort()
+                + " dport: " + getDstPort()
+                + " seq: " + tcpSeq
+                + " ack: " + tcpAck
+                + " window: " + tcpWindow
+                + " windowScale: " + tcpWindowScale
+                + " tos: " + ipTos
+                + " ttl: " + ipTtl;
+    }
+}
diff --git a/services/core/java/com/android/server/connectivity/TcpKeepaliveController.java b/services/core/java/com/android/server/connectivity/TcpKeepaliveController.java
index 1129899ee3ff..b5f20d70db7f 100644
--- a/services/core/java/com/android/server/connectivity/TcpKeepaliveController.java
+++ b/services/core/java/com/android/server/connectivity/TcpKeepaliveController.java
@@ -36,6 +36,7 @@ import android.net.SocketKeepalive.InvalidSocketException;
 import android.net.TcpKeepalivePacketData;
 import android.net.TcpKeepalivePacketDataParcelable;
 import android.net.TcpRepairWindow;
+import android.net.util.KeepalivePacketDataUtil;
 import android.os.Handler;
 import android.os.MessageQueue;
 import android.os.Messenger;
@@ -112,7 +113,7 @@ public class TcpKeepaliveController {
             throws InvalidPacketException, InvalidSocketException {
         try {
             final TcpKeepalivePacketDataParcelable tcpDetails = switchToRepairMode(fd);
-            return TcpKeepalivePacketData.tcpKeepalivePacket(tcpDetails);
+            return KeepalivePacketDataUtil.fromStableParcelable(tcpDetails);
         } catch (InvalidPacketException | InvalidSocketException e) {
             switchOutOfRepairMode(fd);
             throw e;
@@ -122,7 +123,7 @@ public class TcpKeepaliveController {
      * Switch the tcp socket to repair mode and query detail tcp information.
      *
      * @param fd the fd of socket on which to use keepalive offload.
-     * @return a {@link TcpKeepalivePacketData#TcpKeepalivePacketDataParcelable} object for current
+     * @return a {@link TcpKeepalivePacketDataParcelable} object for current
      * tcp/ip information.
      */
     private static TcpKeepalivePacketDataParcelable switchToRepairMode(FileDescriptor fd)
diff --git a/services/net/Android.bp b/services/net/Android.bp
index 29bf37460568..ae9bd41b9db0 100644
--- a/services/net/Android.bp
+++ b/services/net/Android.bp
@@ -37,7 +37,6 @@ java_library {
         "java/android/net/util/NetworkConstants.java",
         "java/android/net/IpMemoryStore.java",
         "java/android/net/NetworkMonitorManager.java",
-        "java/android/net/TcpKeepalivePacketData.java",
     ],
     sdk_version: "module_current",
     min_sdk_version: "30",
diff --git a/services/net/java/android/net/TcpKeepalivePacketData.java b/services/net/java/android/net/TcpKeepalivePacketData.java
deleted file mode 100644
index 4875c7cc4263..000000000000
--- a/services/net/java/android/net/TcpKeepalivePacketData.java
+++ /dev/null
@@ -1,268 +0,0 @@
-/*
- * Copyright (C) 2019 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.SocketKeepalive.ERROR_INVALID_IP_ADDRESS;
-
-import android.annotation.NonNull;
-import android.annotation.Nullable;
-import android.os.Parcel;
-import android.os.Parcelable;
-import android.system.OsConstants;
-
-import com.android.net.module.util.IpUtils;
-
-import java.net.InetAddress;
-import java.net.UnknownHostException;
-import java.nio.ByteBuffer;
-import java.nio.ByteOrder;
-import java.util.Objects;
-
-/**
- * Represents the actual tcp keep alive packets which will be used for hardware offload.
- * @hide
- */
-public class TcpKeepalivePacketData extends KeepalivePacketData implements Parcelable {
-    private static final String TAG = "TcpKeepalivePacketData";
-
-    /** TCP sequence number. */
-    public final int tcpSeq;
-
-    /** TCP ACK number. */
-    public final int tcpAck;
-
-    /** TCP RCV window. */
-    public final int tcpWnd;
-
-    /** TCP RCV window scale. */
-    public final int tcpWndScale;
-
-    /** IP TOS. */
-    public final int ipTos;
-
-    /** IP TTL. */
-    public final int ipTtl;
-
-    private static final int IPV4_HEADER_LENGTH = 20;
-    private static final int IPV6_HEADER_LENGTH = 40;
-    private static final int TCP_HEADER_LENGTH = 20;
-
-    // This should only be constructed via static factory methods, such as
-    // tcpKeepalivePacket.
-    private TcpKeepalivePacketData(final TcpKeepalivePacketDataParcelable tcpDetails,
-            final byte[] data) throws InvalidPacketException, UnknownHostException {
-        super(InetAddress.getByAddress(tcpDetails.srcAddress), tcpDetails.srcPort,
-                InetAddress.getByAddress(tcpDetails.dstAddress), tcpDetails.dstPort, data);
-        tcpSeq = tcpDetails.seq;
-        tcpAck = tcpDetails.ack;
-        // In the packet, the window is shifted right by the window scale.
-        tcpWnd = tcpDetails.rcvWnd;
-        tcpWndScale = tcpDetails.rcvWndScale;
-        ipTos = tcpDetails.tos;
-        ipTtl = tcpDetails.ttl;
-    }
-
-    private TcpKeepalivePacketData(final InetAddress srcAddress, int srcPort,
-            final InetAddress dstAddress, int dstPort, final byte[] data, int tcpSeq,
-            int tcpAck, int tcpWnd, int tcpWndScale, int ipTos, int ipTtl)
-            throws InvalidPacketException {
-        super(srcAddress, srcPort, dstAddress, dstPort, data);
-        this.tcpSeq = tcpSeq;
-        this.tcpAck = tcpAck;
-        this.tcpWnd = tcpWnd;
-        this.tcpWndScale = tcpWndScale;
-        this.ipTos = ipTos;
-        this.ipTtl = ipTtl;
-    }
-
-    /**
-     * Factory method to create tcp keepalive packet structure.
-     */
-    public static TcpKeepalivePacketData tcpKeepalivePacket(
-            TcpKeepalivePacketDataParcelable tcpDetails) throws InvalidPacketException {
-        final byte[] packet;
-        try {
-            if ((tcpDetails.srcAddress != null) && (tcpDetails.dstAddress != null)
-                    && (tcpDetails.srcAddress.length == 4 /* V4 IP length */)
-                    && (tcpDetails.dstAddress.length == 4 /* V4 IP length */)) {
-                packet = buildV4Packet(tcpDetails);
-            } else {
-                // TODO: support ipv6
-                throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS);
-            }
-            return new TcpKeepalivePacketData(tcpDetails, packet);
-        } catch (UnknownHostException e) {
-            throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS);
-        }
-
-    }
-
-    /**
-     * Build ipv4 tcp keepalive packet, not including the link-layer header.
-     */
-    // TODO : if this code is ever moved to the network stack, factorize constants with the ones
-    // over there.
-    private static byte[] buildV4Packet(TcpKeepalivePacketDataParcelable tcpDetails) {
-        final int length = IPV4_HEADER_LENGTH + TCP_HEADER_LENGTH;
-        ByteBuffer buf = ByteBuffer.allocate(length);
-        buf.order(ByteOrder.BIG_ENDIAN);
-        buf.put((byte) 0x45);                       // IP version and IHL
-        buf.put((byte) tcpDetails.tos);             // TOS
-        buf.putShort((short) length);
-        buf.putInt(0x00004000);                     // ID, flags=DF, offset
-        buf.put((byte) tcpDetails.ttl);             // TTL
-        buf.put((byte) OsConstants.IPPROTO_TCP);
-        final int ipChecksumOffset = buf.position();
-        buf.putShort((short) 0);                    // IP checksum
-        buf.put(tcpDetails.srcAddress);
-        buf.put(tcpDetails.dstAddress);
-        buf.putShort((short) tcpDetails.srcPort);
-        buf.putShort((short) tcpDetails.dstPort);
-        buf.putInt(tcpDetails.seq);                 // Sequence Number
-        buf.putInt(tcpDetails.ack);                 // ACK
-        buf.putShort((short) 0x5010);               // TCP length=5, flags=ACK
-        buf.putShort((short) (tcpDetails.rcvWnd >> tcpDetails.rcvWndScale));   // Window size
-        final int tcpChecksumOffset = buf.position();
-        buf.putShort((short) 0);                    // TCP checksum
-        // URG is not set therefore the urgent pointer is zero.
-        buf.putShort((short) 0);                    // Urgent pointer
-
-        buf.putShort(ipChecksumOffset, IpUtils.ipChecksum(buf, 0));
-        buf.putShort(tcpChecksumOffset, IpUtils.tcpChecksum(
-                buf, 0, IPV4_HEADER_LENGTH, TCP_HEADER_LENGTH));
-
-        return buf.array();
-    }
-
-    // TODO: add buildV6Packet.
-
-    @Override
-    public boolean equals(@Nullable final Object o) {
-        if (!(o instanceof TcpKeepalivePacketData)) return false;
-        final TcpKeepalivePacketData other = (TcpKeepalivePacketData) o;
-        final InetAddress srcAddress = getSrcAddress();
-        final InetAddress dstAddress = getDstAddress();
-        return srcAddress.equals(other.getSrcAddress())
-                && dstAddress.equals(other.getDstAddress())
-                && getSrcPort() == other.getSrcPort()
-                && getDstPort() == other.getDstPort()
-                && this.tcpAck == other.tcpAck
-                && this.tcpSeq == other.tcpSeq
-                && this.tcpWnd == other.tcpWnd
-                && this.tcpWndScale == other.tcpWndScale
-                && this.ipTos == other.ipTos
-                && this.ipTtl == other.ipTtl;
-    }
-
-    @Override
-    public int hashCode() {
-        return Objects.hash(getSrcAddress(), getDstAddress(), getSrcPort(), getDstPort(),
-                tcpAck, tcpSeq, tcpWnd, tcpWndScale, ipTos, ipTtl);
-    }
-
-    /**
-     * Parcelable Implementation.
-     * Note that this object implements parcelable (and needs to keep doing this as it inherits
-     * from a class that does), but should usually be parceled as a stable parcelable using
-     * the toStableParcelable() and fromStableParcelable() methods.
-     */
-    public int describeContents() {
-        return 0;
-    }
-
-    /** Write to parcel. */
-    public void writeToParcel(Parcel out, int flags) {
-        out.writeString(getSrcAddress().getHostAddress());
-        out.writeString(getDstAddress().getHostAddress());
-        out.writeInt(getSrcPort());
-        out.writeInt(getDstPort());
-        out.writeByteArray(getPacket());
-        out.writeInt(tcpSeq);
-        out.writeInt(tcpAck);
-        out.writeInt(tcpWnd);
-        out.writeInt(tcpWndScale);
-        out.writeInt(ipTos);
-        out.writeInt(ipTtl);
-    }
-
-    private static TcpKeepalivePacketData readFromParcel(Parcel in) throws InvalidPacketException {
-        InetAddress srcAddress = InetAddresses.parseNumericAddress(in.readString());
-        InetAddress dstAddress = InetAddresses.parseNumericAddress(in.readString());
-        int srcPort = in.readInt();
-        int dstPort = in.readInt();
-        byte[] packet = in.createByteArray();
-        int tcpSeq = in.readInt();
-        int tcpAck = in.readInt();
-        int tcpWnd = in.readInt();
-        int tcpWndScale = in.readInt();
-        int ipTos = in.readInt();
-        int ipTtl = in.readInt();
-        return new TcpKeepalivePacketData(srcAddress, srcPort, dstAddress, dstPort, packet, tcpSeq,
-                tcpAck, tcpWnd, tcpWndScale, ipTos, ipTtl);
-    }
-
-    /** Parcelable Creator. */
-    public static final @NonNull Parcelable.Creator<TcpKeepalivePacketData> CREATOR =
-            new Parcelable.Creator<TcpKeepalivePacketData>() {
-                public TcpKeepalivePacketData createFromParcel(Parcel in) {
-                    try {
-                        return readFromParcel(in);
-                    } catch (InvalidPacketException e) {
-                        throw new IllegalArgumentException(
-                                "Invalid NAT-T keepalive data: " + e.getError());
-                    }
-                }
-
-                public TcpKeepalivePacketData[] newArray(int size) {
-                    return new TcpKeepalivePacketData[size];
-                }
-            };
-
-    /**
-     * Convert this TcpKeepalivePacketData to a TcpKeepalivePacketDataParcelable.
-     */
-    @NonNull
-    public TcpKeepalivePacketDataParcelable toStableParcelable() {
-        final TcpKeepalivePacketDataParcelable parcel = new TcpKeepalivePacketDataParcelable();
-        final InetAddress srcAddress = getSrcAddress();
-        final InetAddress dstAddress = getDstAddress();
-        parcel.srcAddress = srcAddress.getAddress();
-        parcel.srcPort = getSrcPort();
-        parcel.dstAddress = dstAddress.getAddress();
-        parcel.dstPort = getDstPort();
-        parcel.seq = tcpSeq;
-        parcel.ack = tcpAck;
-        parcel.rcvWnd = tcpWnd;
-        parcel.rcvWndScale = tcpWndScale;
-        parcel.tos = ipTos;
-        parcel.ttl = ipTtl;
-        return parcel;
-    }
-
-    @Override
-    public String toString() {
-        return "saddr: " + getSrcAddress()
-                + " daddr: " + getDstAddress()
-                + " sport: " + getSrcPort()
-                + " dport: " + getDstPort()
-                + " seq: " + tcpSeq
-                + " ack: " + tcpAck
-                + " wnd: " + tcpWnd
-                + " wndScale: " + tcpWndScale
-                + " tos: " + ipTos
-                + " ttl: " + ipTtl;
-    }
-}
diff --git a/services/net/java/android/net/ip/IpClientManager.java b/services/net/java/android/net/ip/IpClientManager.java
index db464e732e91..274b6dc1769b 100644
--- a/services/net/java/android/net/ip/IpClientManager.java
+++ b/services/net/java/android/net/ip/IpClientManager.java
@@ -21,6 +21,7 @@ import android.annotation.NonNull;
 import android.net.NattKeepalivePacketData;
 import android.net.ProxyInfo;
 import android.net.TcpKeepalivePacketData;
+import android.net.TcpKeepalivePacketDataParcelable;
 import android.net.shared.Layer2Information;
 import android.net.shared.ProvisioningConfiguration;
 import android.net.util.KeepalivePacketDataUtil;
@@ -215,9 +216,20 @@ public class IpClientManager {
      * Add a TCP keepalive packet filter before setting up keepalive offload.
      */
     public boolean addKeepalivePacketFilter(int slot, TcpKeepalivePacketData pkt) {
+        return addKeepalivePacketFilter(slot, KeepalivePacketDataUtil.toStableParcelable(pkt));
+    }
+
+    /**
+     * Add a TCP keepalive packet filter before setting up keepalive offload.
+     * @deprecated This method is for use on pre-S platforms where TcpKeepalivePacketData is not
+     *             system API. On newer platforms use
+     *             addKeepalivePacketFilter(int, TcpKeepalivePacketData) instead.
+     */
+    @Deprecated
+    public boolean addKeepalivePacketFilter(int slot, TcpKeepalivePacketDataParcelable pkt) {
         final long token = Binder.clearCallingIdentity();
         try {
-            mIpClient.addKeepalivePacketFilter(slot, pkt.toStableParcelable());
+            mIpClient.addKeepalivePacketFilter(slot, pkt);
             return true;
         } catch (RemoteException e) {
             log("Error adding Keepalive Packet Filter ", e);
diff --git a/services/net/java/android/net/util/KeepalivePacketDataUtil.java b/services/net/java/android/net/util/KeepalivePacketDataUtil.java
index 4466ea0abe0e..f06070b6870d 100644
--- a/services/net/java/android/net/util/KeepalivePacketDataUtil.java
+++ b/services/net/java/android/net/util/KeepalivePacketDataUtil.java
@@ -16,20 +16,41 @@
 
 package android.net.util;
 
+import static android.net.SocketKeepalive.ERROR_INVALID_IP_ADDRESS;
+
 import android.annotation.NonNull;
+import android.net.InvalidPacketException;
 import android.net.NattKeepalivePacketData;
 import android.net.NattKeepalivePacketDataParcelable;
+import android.net.TcpKeepalivePacketData;
+import android.net.TcpKeepalivePacketDataParcelable;
+import android.system.OsConstants;
+
+import com.android.net.module.util.IpUtils;
 
 import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
 
-/** @hide */
+/**
+ * Utility class to convert to/from keepalive data parcelables.
+ *
+ * TODO: move to networkstack-client library when it is moved to frameworks/libs/net.
+ * This class cannot go into other shared libraries as it depends on NetworkStack AIDLs.
+ * @hide
+ */
 public final class KeepalivePacketDataUtil {
-     /**
-     * Convert this NattKeepalivePacketData to a NattKeepalivePacketDataParcelable.
+    private static final int IPV4_HEADER_LENGTH = 20;
+    private static final int IPV6_HEADER_LENGTH = 40;
+    private static final int TCP_HEADER_LENGTH = 20;
+
+    /**
+     * Convert a NattKeepalivePacketData to a NattKeepalivePacketDataParcelable.
      */
     @NonNull
     public static NattKeepalivePacketDataParcelable toStableParcelable(
-            NattKeepalivePacketData pkt) {
+            @NonNull NattKeepalivePacketData pkt) {
         final NattKeepalivePacketDataParcelable parcel = new NattKeepalivePacketDataParcelable();
         final InetAddress srcAddress = pkt.getSrcAddress();
         final InetAddress dstAddress = pkt.getDstAddress();
@@ -39,4 +60,95 @@ public final class KeepalivePacketDataUtil {
         parcel.dstPort = pkt.getDstPort();
         return parcel;
     }
+
+    /**
+     * Convert a TcpKeepalivePacketData to a TcpKeepalivePacketDataParcelable.
+     */
+    @NonNull
+    public static TcpKeepalivePacketDataParcelable toStableParcelable(
+            @NonNull TcpKeepalivePacketData pkt) {
+        final TcpKeepalivePacketDataParcelable parcel = new TcpKeepalivePacketDataParcelable();
+        final InetAddress srcAddress = pkt.getSrcAddress();
+        final InetAddress dstAddress = pkt.getDstAddress();
+        parcel.srcAddress = srcAddress.getAddress();
+        parcel.srcPort = pkt.getSrcPort();
+        parcel.dstAddress = dstAddress.getAddress();
+        parcel.dstPort = pkt.getDstPort();
+        parcel.seq = pkt.tcpSeq;
+        parcel.ack = pkt.tcpAck;
+        parcel.rcvWnd = pkt.tcpWindow;
+        parcel.rcvWndScale = pkt.tcpWindowScale;
+        parcel.tos = pkt.ipTos;
+        parcel.ttl = pkt.ipTtl;
+        return parcel;
+    }
+
+    /**
+     * Factory method to create tcp keepalive packet structure.
+     * @hide
+     */
+    public static TcpKeepalivePacketData fromStableParcelable(
+            TcpKeepalivePacketDataParcelable tcpDetails) throws InvalidPacketException {
+        final byte[] packet;
+        try {
+            if ((tcpDetails.srcAddress != null) && (tcpDetails.dstAddress != null)
+                    && (tcpDetails.srcAddress.length == 4 /* V4 IP length */)
+                    && (tcpDetails.dstAddress.length == 4 /* V4 IP length */)) {
+                packet = buildV4Packet(tcpDetails);
+            } else {
+                // TODO: support ipv6
+                throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS);
+            }
+            return new TcpKeepalivePacketData(
+                    InetAddress.getByAddress(tcpDetails.srcAddress),
+                    tcpDetails.srcPort,
+                    InetAddress.getByAddress(tcpDetails.dstAddress),
+                    tcpDetails.dstPort,
+                    packet,
+                    tcpDetails.seq, tcpDetails.ack, tcpDetails.rcvWnd, tcpDetails.rcvWndScale,
+                    tcpDetails.tos, tcpDetails.ttl);
+        } catch (UnknownHostException e) {
+            throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS);
+        }
+
+    }
+
+    /**
+     * Build ipv4 tcp keepalive packet, not including the link-layer header.
+     */
+    // TODO : if this code is ever moved to the network stack, factorize constants with the ones
+    // over there.
+    private static byte[] buildV4Packet(TcpKeepalivePacketDataParcelable tcpDetails) {
+        final int length = IPV4_HEADER_LENGTH + TCP_HEADER_LENGTH;
+        ByteBuffer buf = ByteBuffer.allocate(length);
+        buf.order(ByteOrder.BIG_ENDIAN);
+        buf.put((byte) 0x45);                       // IP version and IHL
+        buf.put((byte) tcpDetails.tos);             // TOS
+        buf.putShort((short) length);
+        buf.putInt(0x00004000);                     // ID, flags=DF, offset
+        buf.put((byte) tcpDetails.ttl);             // TTL
+        buf.put((byte) OsConstants.IPPROTO_TCP);
+        final int ipChecksumOffset = buf.position();
+        buf.putShort((short) 0);                    // IP checksum
+        buf.put(tcpDetails.srcAddress);
+        buf.put(tcpDetails.dstAddress);
+        buf.putShort((short) tcpDetails.srcPort);
+        buf.putShort((short) tcpDetails.dstPort);
+        buf.putInt(tcpDetails.seq);                 // Sequence Number
+        buf.putInt(tcpDetails.ack);                 // ACK
+        buf.putShort((short) 0x5010);               // TCP length=5, flags=ACK
+        buf.putShort((short) (tcpDetails.rcvWnd >> tcpDetails.rcvWndScale));   // Window size
+        final int tcpChecksumOffset = buf.position();
+        buf.putShort((short) 0);                    // TCP checksum
+        // URG is not set therefore the urgent pointer is zero.
+        buf.putShort((short) 0);                    // Urgent pointer
+
+        buf.putShort(ipChecksumOffset, com.android.net.module.util.IpUtils.ipChecksum(buf, 0));
+        buf.putShort(tcpChecksumOffset, IpUtils.tcpChecksum(
+                buf, 0, IPV4_HEADER_LENGTH, TCP_HEADER_LENGTH));
+
+        return buf.array();
+    }
+
+    // TODO: add buildV6Packet.
 }
diff --git a/tests/net/common/java/android/net/TcpKeepalivePacketDataTest.kt b/tests/net/common/java/android/net/TcpKeepalivePacketDataTest.kt
new file mode 100644
index 000000000000..677006692f84
--- /dev/null
+++ b/tests/net/common/java/android/net/TcpKeepalivePacketDataTest.kt
@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2020 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 android.net.InetAddresses.parseNumericAddress
+import android.os.Build
+import com.android.testutils.DevSdkIgnoreRule
+import com.android.testutils.DevSdkIgnoreRunner
+import com.android.testutils.assertFieldCountEquals
+import com.android.testutils.assertParcelSane
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.net.InetAddress
+import kotlin.test.assertEquals
+import kotlin.test.assertNotEquals
+import kotlin.test.assertTrue
+
+@RunWith(DevSdkIgnoreRunner::class)
+@DevSdkIgnoreRule.IgnoreUpTo(Build.VERSION_CODES.R) // TcpKeepalivePacketData added to SDK in S
+class TcpKeepalivePacketDataTest {
+    private fun makeData(
+        srcAddress: InetAddress = parseNumericAddress("192.0.2.123"),
+        srcPort: Int = 1234,
+        dstAddress: InetAddress = parseNumericAddress("192.0.2.231"),
+        dstPort: Int = 4321,
+        data: ByteArray = byteArrayOf(1, 2, 3),
+        tcpSeq: Int = 135,
+        tcpAck: Int = 246,
+        tcpWnd: Int = 1234,
+        tcpWndScale: Int = 2,
+        ipTos: Int = 0x12,
+        ipTtl: Int = 10
+    ) = TcpKeepalivePacketData(srcAddress, srcPort, dstAddress, dstPort, data, tcpSeq, tcpAck,
+            tcpWnd, tcpWndScale, ipTos, ipTtl)
+
+    @Test
+    fun testEquals() {
+        val data1 = makeData()
+        val data2 = makeData()
+        assertEquals(data1, data2)
+        assertEquals(data1.hashCode(), data2.hashCode())
+    }
+
+    @Test
+    fun testNotEquals() {
+        assertNotEquals(makeData(srcAddress = parseNumericAddress("192.0.2.124")), makeData())
+        assertNotEquals(makeData(srcPort = 1235), makeData())
+        assertNotEquals(makeData(dstAddress = parseNumericAddress("192.0.2.232")), makeData())
+        assertNotEquals(makeData(dstPort = 4322), makeData())
+        // .equals does not test .packet, as it should be generated from the other fields
+        assertNotEquals(makeData(tcpSeq = 136), makeData())
+        assertNotEquals(makeData(tcpAck = 247), makeData())
+        assertNotEquals(makeData(tcpWnd = 1235), makeData())
+        assertNotEquals(makeData(tcpWndScale = 3), makeData())
+        assertNotEquals(makeData(ipTos = 0x14), makeData())
+        assertNotEquals(makeData(ipTtl = 11), makeData())
+
+        // Update above assertions if field is added
+        assertFieldCountEquals(5, KeepalivePacketData::class.java)
+        assertFieldCountEquals(6, TcpKeepalivePacketData::class.java)
+    }
+
+    @Test
+    fun testParcelUnparcel() {
+        assertParcelSane(makeData(), fieldCount = 6) { a, b ->
+            // .equals() does not verify .packet
+            a == b && a.packet contentEquals b.packet
+        }
+    }
+
+    @Test
+    fun testToString() {
+        val data = makeData()
+        val str = data.toString()
+
+        assertTrue(str.contains(data.srcAddress.hostAddress))
+        assertTrue(str.contains(data.srcPort.toString()))
+        assertTrue(str.contains(data.dstAddress.hostAddress))
+        assertTrue(str.contains(data.dstPort.toString()))
+        // .packet not included in toString()
+        assertTrue(str.contains(data.tcpSeq.toString()))
+        assertTrue(str.contains(data.tcpAck.toString()))
+        assertTrue(str.contains(data.tcpWindow.toString()))
+        assertTrue(str.contains(data.tcpWindowScale.toString()))
+        assertTrue(str.contains(data.ipTos.toString()))
+        assertTrue(str.contains(data.ipTtl.toString()))
+
+        // Update above assertions if field is added
+        assertFieldCountEquals(5, KeepalivePacketData::class.java)
+        assertFieldCountEquals(6, TcpKeepalivePacketData::class.java)
+    }
+}
\ No newline at end of file
diff --git a/tests/net/java/android/net/TcpKeepalivePacketDataTest.java b/tests/net/java/android/net/KeepalivePacketDataUtilTest.java
index c5b25bdcac48..9ae3595adbdb 100644
--- a/tests/net/java/android/net/TcpKeepalivePacketDataTest.java
+++ b/tests/net/java/android/net/KeepalivePacketDataUtilTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019 The Android Open Source Project
+ * Copyright (C) 2020 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.
@@ -22,6 +22,8 @@ import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
 
+import android.net.util.KeepalivePacketDataUtil;
+
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -31,7 +33,7 @@ import java.net.InetAddress;
 import java.nio.ByteBuffer;
 
 @RunWith(JUnit4.class)
-public final class TcpKeepalivePacketDataTest {
+public final class KeepalivePacketDataUtilTest {
     private static final byte[] IPV4_KEEPALIVE_SRC_ADDR = {10, 0, 0, 1};
     private static final byte[] IPV4_KEEPALIVE_DST_ADDR = {10, 0, 0, 5};
 
@@ -39,7 +41,7 @@ public final class TcpKeepalivePacketDataTest {
     public void setUp() {}
 
     @Test
-    public void testV4TcpKeepalivePacket() throws Exception {
+    public void testFromTcpKeepaliveStableParcelable() throws Exception {
         final int srcPort = 1234;
         final int dstPort = 4321;
         final int seq = 0x11111111;
@@ -61,7 +63,7 @@ public final class TcpKeepalivePacketDataTest {
         testInfo.tos = tos;
         testInfo.ttl = ttl;
         try {
-            resultData = TcpKeepalivePacketData.tcpKeepalivePacket(testInfo);
+            resultData = KeepalivePacketDataUtil.fromStableParcelable(testInfo);
         } catch (InvalidPacketException e) {
             fail("InvalidPacketException: " + e);
         }
@@ -72,8 +74,8 @@ public final class TcpKeepalivePacketDataTest {
         assertEquals(testInfo.dstPort, resultData.getDstPort());
         assertEquals(testInfo.seq, resultData.tcpSeq);
         assertEquals(testInfo.ack, resultData.tcpAck);
-        assertEquals(testInfo.rcvWnd, resultData.tcpWnd);
-        assertEquals(testInfo.rcvWndScale, resultData.tcpWndScale);
+        assertEquals(testInfo.rcvWnd, resultData.tcpWindow);
+        assertEquals(testInfo.rcvWndScale, resultData.tcpWindowScale);
         assertEquals(testInfo.tos, resultData.ipTos);
         assertEquals(testInfo.ttl, resultData.ipTtl);
 
@@ -113,7 +115,7 @@ public final class TcpKeepalivePacketDataTest {
     //TODO: add ipv6 test when ipv6 supported
 
     @Test
-    public void testParcel() throws Exception {
+    public void testToTcpKeepaliveStableParcelable() throws Exception {
         final int srcPort = 1234;
         final int dstPort = 4321;
         final int sequence = 0x11111111;
@@ -135,8 +137,8 @@ public final class TcpKeepalivePacketDataTest {
         testInfo.ttl = ttl;
         TcpKeepalivePacketData testData = null;
         TcpKeepalivePacketDataParcelable resultData = null;
-        testData = TcpKeepalivePacketData.tcpKeepalivePacket(testInfo);
-        resultData = testData.toStableParcelable();
+        testData = KeepalivePacketDataUtil.fromStableParcelable(testInfo);
+        resultData = KeepalivePacketDataUtil.toStableParcelable(testData);
         assertArrayEquals(resultData.srcAddress, IPV4_KEEPALIVE_SRC_ADDR);
         assertArrayEquals(resultData.dstAddress, IPV4_KEEPALIVE_DST_ADDR);
         assertEquals(resultData.srcPort, srcPort);