Move NetworkUtils used by NetworkStack

Depending on usage move into NetworkStackUtils or shared
Inet4AddressUtils.

Test: atest FrameworksNetTests NetworkStackTests
Bug: 112869080
(Cherry-pick of aosp/881952)
Change-Id: Ie20dcee375b377236004a7689890729493aca857
diff --git a/Android.bp b/Android.bp
index 56f3c23..813e98c 100644
--- a/Android.bp
+++ b/Android.bp
@@ -912,6 +912,27 @@
     api_dir: "aidl/networkstack",
 }
 
+filegroup {
+    name: "framework-networkstack-shared-srcs",
+    srcs: [
+        // TODO: remove these annotations as soon as we can use andoid.support.annotations.*
+        "core/java/android/annotation/NonNull.java",
+        "core/java/android/annotation/Nullable.java",
+        "core/java/android/annotation/IntDef.java",
+        "core/java/android/annotation/UnsupportedAppUsage.java",
+        "core/java/android/util/LocalLog.java",
+        "core/java/com/android/internal/annotations/VisibleForTesting.java",
+        "core/java/com/android/internal/util/HexDump.java",
+        "core/java/com/android/internal/util/IState.java",
+        "core/java/com/android/internal/util/MessageUtils.java",
+        "core/java/com/android/internal/util/Preconditions.java",
+        "core/java/com/android/internal/util/State.java",
+        "core/java/com/android/internal/util/StateMachine.java",
+        "core/java/com/android/internal/util/WakeupMessage.java",
+        "core/java/android/net/shared/*.java",
+    ]
+}
+
 // Build ext.jar
 // ============================================================
 java_library {
diff --git a/core/java/android/net/NetworkUtils.java b/core/java/android/net/NetworkUtils.java
index c996d01..39db4fe 100644
--- a/core/java/android/net/NetworkUtils.java
+++ b/core/java/android/net/NetworkUtils.java
@@ -21,8 +21,10 @@
 
 import android.annotation.NonNull;
 import android.annotation.UnsupportedAppUsage;
+import android.net.shared.Inet4AddressUtils;
 import android.os.Build;
 import android.os.Parcel;
+import android.system.ErrnoException;
 import android.system.Os;
 import android.util.Log;
 import android.util.Pair;
@@ -39,8 +41,6 @@
 import java.util.Locale;
 import java.util.TreeSet;
 
-import android.system.ErrnoException;
-
 /**
  * Native methods for managing network interfaces.
  *
@@ -177,119 +177,37 @@
             FileDescriptor fd) throws IOException;
 
     /**
-     * @see #intToInet4AddressHTL(int)
-     * @deprecated Use either {@link #intToInet4AddressHTH(int)}
-     *             or {@link #intToInet4AddressHTL(int)}
+     * @see Inet4AddressUtils#intToInet4AddressHTL(int)
+     * @deprecated Use either {@link Inet4AddressUtils#intToInet4AddressHTH(int)}
+     *             or {@link Inet4AddressUtils#intToInet4AddressHTL(int)}
      */
     @Deprecated
     @UnsupportedAppUsage
     public static InetAddress intToInetAddress(int hostAddress) {
-        return intToInet4AddressHTL(hostAddress);
+        return Inet4AddressUtils.intToInet4AddressHTL(hostAddress);
     }
 
     /**
-     * Convert a IPv4 address from an integer to an InetAddress (0x04030201 -> 1.2.3.4)
-     *
-     * <p>This method uses the higher-order int bytes as the lower-order IPv4 address bytes,
-     * which is an unusual convention. Consider {@link #intToInet4AddressHTH(int)} instead.
-     * @param hostAddress an int coding for an IPv4 address, where higher-order int byte is
-     *                    lower-order IPv4 address byte
-     */
-    public static Inet4Address intToInet4AddressHTL(int hostAddress) {
-        return intToInet4AddressHTH(Integer.reverseBytes(hostAddress));
-    }
-
-    /**
-     * Convert a IPv4 address from an integer to an InetAddress (0x01020304 -> 1.2.3.4)
-     * @param hostAddress an int coding for an IPv4 address
-     */
-    public static Inet4Address intToInet4AddressHTH(int hostAddress) {
-        byte[] addressBytes = { (byte) (0xff & (hostAddress >> 24)),
-                (byte) (0xff & (hostAddress >> 16)),
-                (byte) (0xff & (hostAddress >> 8)),
-                (byte) (0xff & hostAddress) };
-
-        try {
-            return (Inet4Address) InetAddress.getByAddress(addressBytes);
-        } catch (UnknownHostException e) {
-            throw new AssertionError();
-        }
-    }
-
-    /**
-     * @see #inet4AddressToIntHTL(Inet4Address)
-     * @deprecated Use either {@link #inet4AddressToIntHTH(Inet4Address)}
-     *             or {@link #inet4AddressToIntHTL(Inet4Address)}
+     * @see Inet4AddressUtils#inet4AddressToIntHTL(Inet4Address)
+     * @deprecated Use either {@link Inet4AddressUtils#inet4AddressToIntHTH(Inet4Address)}
+     *             or {@link Inet4AddressUtils#inet4AddressToIntHTL(Inet4Address)}
      */
     @Deprecated
     public static int inetAddressToInt(Inet4Address inetAddr)
             throws IllegalArgumentException {
-        return inet4AddressToIntHTL(inetAddr);
+        return Inet4AddressUtils.inet4AddressToIntHTL(inetAddr);
     }
 
     /**
-     * Convert an IPv4 address from an InetAddress to an integer (1.2.3.4 -> 0x01020304)
-     *
-     * <p>This conversion can help order IP addresses: considering the ordering
-     * 192.0.2.1 < 192.0.2.2 < ..., resulting ints will follow that ordering if read as unsigned
-     * integers with {@link Integer#toUnsignedLong}.
-     * @param inetAddr is an InetAddress corresponding to the IPv4 address
-     * @return the IP address as integer
-     */
-    public static int inet4AddressToIntHTH(Inet4Address inetAddr)
-            throws IllegalArgumentException {
-        byte [] addr = inetAddr.getAddress();
-        return ((addr[0] & 0xff) << 24) | ((addr[1] & 0xff) << 16)
-                | ((addr[2] & 0xff) << 8) | (addr[3] & 0xff);
-    }
-
-    /**
-     * Convert a IPv4 address from an InetAddress to an integer (1.2.3.4 -> 0x04030201)
-     *
-     * <p>This method stores the higher-order IPv4 address bytes in the lower-order int bytes,
-     * which is an unusual convention. Consider {@link #inet4AddressToIntHTH(Inet4Address)} instead.
-     * @param inetAddr is an InetAddress corresponding to the IPv4 address
-     * @return the IP address as integer
-     */
-    public static int inet4AddressToIntHTL(Inet4Address inetAddr) {
-        return Integer.reverseBytes(inet4AddressToIntHTH(inetAddr));
-    }
-
-    /**
-     * @see #prefixLengthToV4NetmaskIntHTL(int)
-     * @deprecated Use either {@link #prefixLengthToV4NetmaskIntHTH(int)}
-     *             or {@link #prefixLengthToV4NetmaskIntHTL(int)}
+     * @see Inet4AddressUtils#prefixLengthToV4NetmaskIntHTL(int)
+     * @deprecated Use either {@link Inet4AddressUtils#prefixLengthToV4NetmaskIntHTH(int)}
+     *             or {@link Inet4AddressUtils#prefixLengthToV4NetmaskIntHTL(int)}
      */
     @Deprecated
     @UnsupportedAppUsage
     public static int prefixLengthToNetmaskInt(int prefixLength)
             throws IllegalArgumentException {
-        return prefixLengthToV4NetmaskIntHTL(prefixLength);
-    }
-
-    /**
-     * Convert a network prefix length to an IPv4 netmask integer (prefixLength 17 -> 0xffff8000)
-     * @return the IPv4 netmask as an integer
-     */
-    public static int prefixLengthToV4NetmaskIntHTH(int prefixLength)
-            throws IllegalArgumentException {
-        if (prefixLength < 0 || prefixLength > 32) {
-            throw new IllegalArgumentException("Invalid prefix length (0 <= prefix <= 32)");
-        }
-        // (int)a << b is equivalent to a << (b & 0x1f): can't shift by 32 (-1 << 32 == -1)
-        return prefixLength == 0 ? 0 : 0xffffffff << (32 - prefixLength);
-    }
-
-    /**
-     * Convert a network prefix length to an IPv4 netmask integer (prefixLength 17 -> 0x0080ffff).
-     *
-     * <p>This method stores the higher-order IPv4 address bytes in the lower-order int bytes,
-     * which is an unusual convention. Consider {@link #prefixLengthToV4NetmaskIntHTH(int)} instead.
-     * @return the IPv4 netmask as an integer
-     */
-    public static int prefixLengthToV4NetmaskIntHTL(int prefixLength)
-            throws IllegalArgumentException {
-        return Integer.reverseBytes(prefixLengthToV4NetmaskIntHTH(prefixLength));
+        return Inet4AddressUtils.prefixLengthToV4NetmaskIntHTL(prefixLength);
     }
 
     /**
@@ -307,17 +225,13 @@
      * @return the network prefix length
      * @throws IllegalArgumentException the specified netmask was not contiguous.
      * @hide
+     * @deprecated use {@link Inet4AddressUtils#netmaskToPrefixLength(Inet4Address)}
      */
     @UnsupportedAppUsage
+    @Deprecated
     public static int netmaskToPrefixLength(Inet4Address netmask) {
-        // inetAddressToInt returns an int in *network* byte order.
-        int i = Integer.reverseBytes(inetAddressToInt(netmask));
-        int prefixLength = Integer.bitCount(i);
-        int trailingZeros = Integer.numberOfTrailingZeros(i);
-        if (trailingZeros != 32 - prefixLength) {
-            throw new IllegalArgumentException("Non-contiguous netmask: " + Integer.toHexString(i));
-        }
-        return prefixLength;
+        // This is only here because some apps seem to be using it (@UnsupportedAppUsage).
+        return Inet4AddressUtils.netmaskToPrefixLength(netmask);
     }
 
 
@@ -408,16 +322,8 @@
      */
     @UnsupportedAppUsage
     public static int getImplicitNetmask(Inet4Address address) {
-        int firstByte = address.getAddress()[0] & 0xff;  // Convert to an unsigned value.
-        if (firstByte < 128) {
-            return 8;
-        } else if (firstByte < 192) {
-            return 16;
-        } else if (firstByte < 224) {
-            return 24;
-        } else {
-            return 32;  // Will likely not end well for other reasons.
-        }
+        // Only here because it seems to be used by apps
+        return Inet4AddressUtils.getImplicitNetmask(address);
     }
 
     /**
@@ -445,28 +351,6 @@
     }
 
     /**
-     * Get a prefix mask as Inet4Address for a given prefix length.
-     *
-     * <p>For example 20 -> 255.255.240.0
-     */
-    public static Inet4Address getPrefixMaskAsInet4Address(int prefixLength)
-            throws IllegalArgumentException {
-        return intToInet4AddressHTH(prefixLengthToV4NetmaskIntHTH(prefixLength));
-    }
-
-    /**
-     * Get the broadcast address for a given prefix.
-     *
-     * <p>For example 192.168.0.1/24 -> 192.168.0.255
-     */
-    public static Inet4Address getBroadcastAddress(Inet4Address addr, int prefixLength)
-            throws IllegalArgumentException {
-        final int intBroadcastAddr = inet4AddressToIntHTH(addr)
-                | ~prefixLengthToV4NetmaskIntHTH(prefixLength);
-        return intToInet4AddressHTH(intBroadcastAddr);
-    }
-
-    /**
      * Check if IP address type is consistent between two InetAddress.
      * @return true if both are the same type.  False otherwise.
      */
diff --git a/core/java/android/net/shared/Inet4AddressUtils.java b/core/java/android/net/shared/Inet4AddressUtils.java
new file mode 100644
index 0000000..bec0c84
--- /dev/null
+++ b/core/java/android/net/shared/Inet4AddressUtils.java
@@ -0,0 +1,166 @@
+/*
+ * 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.shared;
+
+import java.net.Inet4Address;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
+/**
+ * Collection of utilities to work with IPv4 addresses.
+ * @hide
+ */
+public class Inet4AddressUtils {
+
+    /**
+     * Convert a IPv4 address from an integer to an InetAddress (0x04030201 -> 1.2.3.4)
+     *
+     * <p>This method uses the higher-order int bytes as the lower-order IPv4 address bytes,
+     * which is an unusual convention. Consider {@link #intToInet4AddressHTH(int)} instead.
+     * @param hostAddress an int coding for an IPv4 address, where higher-order int byte is
+     *                    lower-order IPv4 address byte
+     */
+    public static Inet4Address intToInet4AddressHTL(int hostAddress) {
+        return intToInet4AddressHTH(Integer.reverseBytes(hostAddress));
+    }
+
+    /**
+     * Convert a IPv4 address from an integer to an InetAddress (0x01020304 -> 1.2.3.4)
+     * @param hostAddress an int coding for an IPv4 address
+     */
+    public static Inet4Address intToInet4AddressHTH(int hostAddress) {
+        byte[] addressBytes = { (byte) (0xff & (hostAddress >> 24)),
+                (byte) (0xff & (hostAddress >> 16)),
+                (byte) (0xff & (hostAddress >> 8)),
+                (byte) (0xff & hostAddress) };
+
+        try {
+            return (Inet4Address) InetAddress.getByAddress(addressBytes);
+        } catch (UnknownHostException e) {
+            throw new AssertionError();
+        }
+    }
+
+    /**
+     * Convert an IPv4 address from an InetAddress to an integer (1.2.3.4 -> 0x01020304)
+     *
+     * <p>This conversion can help order IP addresses: considering the ordering
+     * 192.0.2.1 < 192.0.2.2 < ..., resulting ints will follow that ordering if read as unsigned
+     * integers with {@link Integer#toUnsignedLong}.
+     * @param inetAddr is an InetAddress corresponding to the IPv4 address
+     * @return the IP address as integer
+     */
+    public static int inet4AddressToIntHTH(Inet4Address inetAddr)
+            throws IllegalArgumentException {
+        byte [] addr = inetAddr.getAddress();
+        return ((addr[0] & 0xff) << 24) | ((addr[1] & 0xff) << 16)
+                | ((addr[2] & 0xff) << 8) | (addr[3] & 0xff);
+    }
+
+    /**
+     * Convert a IPv4 address from an InetAddress to an integer (1.2.3.4 -> 0x04030201)
+     *
+     * <p>This method stores the higher-order IPv4 address bytes in the lower-order int bytes,
+     * which is an unusual convention. Consider {@link #inet4AddressToIntHTH(Inet4Address)} instead.
+     * @param inetAddr is an InetAddress corresponding to the IPv4 address
+     * @return the IP address as integer
+     */
+    public static int inet4AddressToIntHTL(Inet4Address inetAddr) {
+        return Integer.reverseBytes(inet4AddressToIntHTH(inetAddr));
+    }
+
+    /**
+     * Convert a network prefix length to an IPv4 netmask integer (prefixLength 17 -> 0xffff8000)
+     * @return the IPv4 netmask as an integer
+     */
+    public static int prefixLengthToV4NetmaskIntHTH(int prefixLength)
+            throws IllegalArgumentException {
+        if (prefixLength < 0 || prefixLength > 32) {
+            throw new IllegalArgumentException("Invalid prefix length (0 <= prefix <= 32)");
+        }
+        // (int)a << b is equivalent to a << (b & 0x1f): can't shift by 32 (-1 << 32 == -1)
+        return prefixLength == 0 ? 0 : 0xffffffff << (32 - prefixLength);
+    }
+
+    /**
+     * Convert a network prefix length to an IPv4 netmask integer (prefixLength 17 -> 0x0080ffff).
+     *
+     * <p>This method stores the higher-order IPv4 address bytes in the lower-order int bytes,
+     * which is an unusual convention. Consider {@link #prefixLengthToV4NetmaskIntHTH(int)} instead.
+     * @return the IPv4 netmask as an integer
+     */
+    public static int prefixLengthToV4NetmaskIntHTL(int prefixLength)
+            throws IllegalArgumentException {
+        return Integer.reverseBytes(prefixLengthToV4NetmaskIntHTH(prefixLength));
+    }
+
+    /**
+     * Convert an IPv4 netmask to a prefix length, checking that the netmask is contiguous.
+     * @param netmask as a {@code Inet4Address}.
+     * @return the network prefix length
+     * @throws IllegalArgumentException the specified netmask was not contiguous.
+     * @hide
+     */
+    public static int netmaskToPrefixLength(Inet4Address netmask) {
+        // inetAddressToInt returns an int in *network* byte order.
+        int i = inet4AddressToIntHTH(netmask);
+        int prefixLength = Integer.bitCount(i);
+        int trailingZeros = Integer.numberOfTrailingZeros(i);
+        if (trailingZeros != 32 - prefixLength) {
+            throw new IllegalArgumentException("Non-contiguous netmask: " + Integer.toHexString(i));
+        }
+        return prefixLength;
+    }
+
+    /**
+     * Returns the implicit netmask of an IPv4 address, as was the custom before 1993.
+     */
+    public static int getImplicitNetmask(Inet4Address address) {
+        int firstByte = address.getAddress()[0] & 0xff;  // Convert to an unsigned value.
+        if (firstByte < 128) {
+            return 8;
+        } else if (firstByte < 192) {
+            return 16;
+        } else if (firstByte < 224) {
+            return 24;
+        } else {
+            return 32;  // Will likely not end well for other reasons.
+        }
+    }
+
+    /**
+     * Get the broadcast address for a given prefix.
+     *
+     * <p>For example 192.168.0.1/24 -> 192.168.0.255
+     */
+    public static Inet4Address getBroadcastAddress(Inet4Address addr, int prefixLength)
+            throws IllegalArgumentException {
+        final int intBroadcastAddr = inet4AddressToIntHTH(addr)
+                | ~prefixLengthToV4NetmaskIntHTH(prefixLength);
+        return intToInet4AddressHTH(intBroadcastAddr);
+    }
+
+    /**
+     * Get a prefix mask as Inet4Address for a given prefix length.
+     *
+     * <p>For example 20 -> 255.255.240.0
+     */
+    public static Inet4Address getPrefixMaskAsInet4Address(int prefixLength)
+            throws IllegalArgumentException {
+        return intToInet4AddressHTH(prefixLengthToV4NetmaskIntHTH(prefixLength));
+    }
+}
diff --git a/packages/NetworkStack/Android.bp b/packages/NetworkStack/Android.bp
index a2da0a0..9b0d896 100644
--- a/packages/NetworkStack/Android.bp
+++ b/packages/NetworkStack/Android.bp
@@ -21,6 +21,7 @@
     installable: true,
     srcs: [
         "src/**/*.java",
+        ":framework-networkstack-shared-srcs",
         ":services-networkstack-shared-srcs",
     ],
     static_libs: [
diff --git a/packages/NetworkStack/src/android/net/dhcp/DhcpLeaseRepository.java b/packages/NetworkStack/src/android/net/dhcp/DhcpLeaseRepository.java
index 0d298de..8187279 100644
--- a/packages/NetworkStack/src/android/net/dhcp/DhcpLeaseRepository.java
+++ b/packages/NetworkStack/src/android/net/dhcp/DhcpLeaseRepository.java
@@ -16,11 +16,11 @@
 
 package android.net.dhcp;
 
-import static android.net.NetworkUtils.inet4AddressToIntHTH;
-import static android.net.NetworkUtils.intToInet4AddressHTH;
-import static android.net.NetworkUtils.prefixLengthToV4NetmaskIntHTH;
 import static android.net.dhcp.DhcpLease.EXPIRATION_NEVER;
 import static android.net.dhcp.DhcpLease.inet4AddrToString;
+import static android.net.shared.Inet4AddressUtils.inet4AddressToIntHTH;
+import static android.net.shared.Inet4AddressUtils.intToInet4AddressHTH;
+import static android.net.shared.Inet4AddressUtils.prefixLengthToV4NetmaskIntHTH;
 
 import static com.android.server.util.NetworkStackConstants.IPV4_ADDR_BITS;
 
diff --git a/packages/NetworkStack/src/android/net/dhcp/DhcpPacket.java b/packages/NetworkStack/src/android/net/dhcp/DhcpPacket.java
index ce8b7e7..74c4e72 100644
--- a/packages/NetworkStack/src/android/net/dhcp/DhcpPacket.java
+++ b/packages/NetworkStack/src/android/net/dhcp/DhcpPacket.java
@@ -3,8 +3,8 @@
 import android.annotation.Nullable;
 import android.net.DhcpResults;
 import android.net.LinkAddress;
-import android.net.NetworkUtils;
 import android.net.metrics.DhcpErrorEvent;
+import android.net.shared.Inet4AddressUtils;
 import android.os.Build;
 import android.os.SystemProperties;
 import android.system.OsConstants;
@@ -1222,13 +1222,13 @@
         int prefixLength;
         if (mSubnetMask != null) {
             try {
-                prefixLength = NetworkUtils.netmaskToPrefixLength(mSubnetMask);
+                prefixLength = Inet4AddressUtils.netmaskToPrefixLength(mSubnetMask);
             } catch (IllegalArgumentException e) {
                 // Non-contiguous netmask.
                 return null;
             }
         } else {
-            prefixLength = NetworkUtils.getImplicitNetmask(ipAddress);
+            prefixLength = Inet4AddressUtils.getImplicitNetmask(ipAddress);
         }
 
         DhcpResults results = new DhcpResults();
diff --git a/packages/NetworkStack/src/android/net/dhcp/DhcpServer.java b/packages/NetworkStack/src/android/net/dhcp/DhcpServer.java
index 7b112df..c41c1c9 100644
--- a/packages/NetworkStack/src/android/net/dhcp/DhcpServer.java
+++ b/packages/NetworkStack/src/android/net/dhcp/DhcpServer.java
@@ -16,8 +16,6 @@
 
 package android.net.dhcp;
 
-import static android.net.NetworkUtils.getBroadcastAddress;
-import static android.net.NetworkUtils.getPrefixMaskAsInet4Address;
 import static android.net.TrafficStats.TAG_SYSTEM_DHCP_SERVER;
 import static android.net.dhcp.DhcpPacket.DHCP_CLIENT;
 import static android.net.dhcp.DhcpPacket.DHCP_HOST_NAME;
@@ -25,6 +23,8 @@
 import static android.net.dhcp.DhcpPacket.ENCAP_BOOTP;
 import static android.net.dhcp.IDhcpServer.STATUS_INVALID_ARGUMENT;
 import static android.net.dhcp.IDhcpServer.STATUS_SUCCESS;
+import static android.net.shared.Inet4AddressUtils.getBroadcastAddress;
+import static android.net.shared.Inet4AddressUtils.getPrefixMaskAsInet4Address;
 import static android.system.OsConstants.AF_INET;
 import static android.system.OsConstants.IPPROTO_UDP;
 import static android.system.OsConstants.SOCK_DGRAM;
diff --git a/packages/NetworkStack/src/android/net/dhcp/DhcpServingParams.java b/packages/NetworkStack/src/android/net/dhcp/DhcpServingParams.java
index 868f3be..31ce95b 100644
--- a/packages/NetworkStack/src/android/net/dhcp/DhcpServingParams.java
+++ b/packages/NetworkStack/src/android/net/dhcp/DhcpServingParams.java
@@ -16,8 +16,8 @@
 
 package android.net.dhcp;
 
-import static android.net.NetworkUtils.getPrefixMaskAsInet4Address;
-import static android.net.NetworkUtils.intToInet4AddressHTH;
+import static android.net.shared.Inet4AddressUtils.getPrefixMaskAsInet4Address;
+import static android.net.shared.Inet4AddressUtils.intToInet4AddressHTH;
 
 import static com.android.server.util.NetworkStackConstants.INFINITE_LEASE;
 import static com.android.server.util.NetworkStackConstants.IPV4_MAX_MTU;
@@ -29,7 +29,7 @@
 import android.annotation.Nullable;
 import android.net.IpPrefix;
 import android.net.LinkAddress;
-import android.net.NetworkUtils;
+import android.net.shared.Inet4AddressUtils;
 import android.util.ArraySet;
 
 import java.net.Inet4Address;
@@ -164,7 +164,8 @@
      */
     @NonNull
     public Inet4Address getBroadcastAddress() {
-        return NetworkUtils.getBroadcastAddress(getServerInet4Addr(), serverAddr.getPrefixLength());
+        return Inet4AddressUtils.getBroadcastAddress(
+                getServerInet4Addr(), serverAddr.getPrefixLength());
     }
 
     /**
diff --git a/packages/NetworkStack/tests/src/android/net/dhcp/DhcpPacketTest.java b/packages/NetworkStack/tests/src/android/net/dhcp/DhcpPacketTest.java
index a592809..38f45f7 100644
--- a/packages/NetworkStack/tests/src/android/net/dhcp/DhcpPacketTest.java
+++ b/packages/NetworkStack/tests/src/android/net/dhcp/DhcpPacketTest.java
@@ -16,9 +16,27 @@
 
 package android.net.dhcp;
 
-import static android.net.NetworkUtils.getBroadcastAddress;
-import static android.net.NetworkUtils.getPrefixMaskAsInet4Address;
-import static android.net.dhcp.DhcpPacket.*;
+import static android.net.dhcp.DhcpPacket.DHCP_BROADCAST_ADDRESS;
+import static android.net.dhcp.DhcpPacket.DHCP_DNS_SERVER;
+import static android.net.dhcp.DhcpPacket.DHCP_DOMAIN_NAME;
+import static android.net.dhcp.DhcpPacket.DHCP_LEASE_TIME;
+import static android.net.dhcp.DhcpPacket.DHCP_MESSAGE_TYPE_ACK;
+import static android.net.dhcp.DhcpPacket.DHCP_MESSAGE_TYPE_OFFER;
+import static android.net.dhcp.DhcpPacket.DHCP_MTU;
+import static android.net.dhcp.DhcpPacket.DHCP_REBINDING_TIME;
+import static android.net.dhcp.DhcpPacket.DHCP_RENEWAL_TIME;
+import static android.net.dhcp.DhcpPacket.DHCP_ROUTER;
+import static android.net.dhcp.DhcpPacket.DHCP_SUBNET_MASK;
+import static android.net.dhcp.DhcpPacket.DHCP_VENDOR_INFO;
+import static android.net.dhcp.DhcpPacket.ENCAP_BOOTP;
+import static android.net.dhcp.DhcpPacket.ENCAP_L2;
+import static android.net.dhcp.DhcpPacket.ENCAP_L3;
+import static android.net.dhcp.DhcpPacket.INADDR_ANY;
+import static android.net.dhcp.DhcpPacket.INFINITE_LEASE;
+import static android.net.dhcp.DhcpPacket.ParseException;
+import static android.net.shared.Inet4AddressUtils.getBroadcastAddress;
+import static android.net.shared.Inet4AddressUtils.getPrefixMaskAsInet4Address;
+
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
@@ -30,11 +48,15 @@
 import android.net.LinkAddress;
 import android.net.NetworkUtils;
 import android.net.metrics.DhcpErrorEvent;
-import android.support.test.runner.AndroidJUnit4;
 import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
 
 import com.android.internal.util.HexDump;
 
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
 import java.io.ByteArrayOutputStream;
 import java.net.Inet4Address;
 import java.nio.ByteBuffer;
@@ -44,10 +66,6 @@
 import java.util.Collections;
 import java.util.Random;
 
-import org.junit.Before;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-
 @RunWith(AndroidJUnit4.class)
 @SmallTest
 public class DhcpPacketTest {
diff --git a/packages/NetworkStack/tests/src/android/net/dhcp/DhcpServingParamsTest.java b/packages/NetworkStack/tests/src/android/net/dhcp/DhcpServingParamsTest.java
index 3ca0564..1004382 100644
--- a/packages/NetworkStack/tests/src/android/net/dhcp/DhcpServingParamsTest.java
+++ b/packages/NetworkStack/tests/src/android/net/dhcp/DhcpServingParamsTest.java
@@ -17,8 +17,8 @@
 package android.net.dhcp;
 
 import static android.net.InetAddresses.parseNumericAddress;
-import static android.net.NetworkUtils.inet4AddressToIntHTH;
 import static android.net.dhcp.DhcpServingParams.MTU_UNSET;
+import static android.net.shared.Inet4AddressUtils.inet4AddressToIntHTH;
 
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.assertFalse;
@@ -27,8 +27,8 @@
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.net.LinkAddress;
-import android.net.NetworkUtils;
 import android.net.dhcp.DhcpServingParams.InvalidParameterException;
+import android.net.shared.Inet4AddressUtils;
 import android.support.test.filters.SmallTest;
 import android.support.test.runner.AndroidJUnit4;
 
@@ -200,7 +200,7 @@
     }
 
     private static int[] toIntArray(Collection<Inet4Address> addrs) {
-        return addrs.stream().mapToInt(NetworkUtils::inet4AddressToIntHTH).toArray();
+        return addrs.stream().mapToInt(Inet4AddressUtils::inet4AddressToIntHTH).toArray();
     }
 
     private static <T> void assertContains(@NonNull Set<T> set, @NonNull Set<T> subset) {
diff --git a/services/ipmemorystore/java/com/android/server/net/ipmemorystore/IpMemoryStoreDatabase.java b/services/ipmemorystore/java/com/android/server/net/ipmemorystore/IpMemoryStoreDatabase.java
index e99dd4f..bbecc63 100644
--- a/services/ipmemorystore/java/com/android/server/net/ipmemorystore/IpMemoryStoreDatabase.java
+++ b/services/ipmemorystore/java/com/android/server/net/ipmemorystore/IpMemoryStoreDatabase.java
@@ -16,6 +16,9 @@
 
 package com.android.server.net.ipmemorystore;
 
+import static android.net.shared.Inet4AddressUtils.inet4AddressToIntHTH;
+import static android.net.shared.Inet4AddressUtils.intToInet4AddressHTH;
+
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.content.ContentValues;
@@ -27,7 +30,6 @@
 import android.database.sqlite.SQLiteException;
 import android.database.sqlite.SQLiteOpenHelper;
 import android.database.sqlite.SQLiteQuery;
-import android.net.NetworkUtils;
 import android.net.ipmemorystore.NetworkAttributes;
 import android.net.ipmemorystore.Status;
 import android.util.Log;
@@ -200,7 +202,7 @@
         if (null == attributes) return values;
         if (null != attributes.assignedV4Address) {
             values.put(NetworkAttributesContract.COLNAME_ASSIGNEDV4ADDRESS,
-                    NetworkUtils.inet4AddressToIntHTH(attributes.assignedV4Address));
+                    inet4AddressToIntHTH(attributes.assignedV4Address));
         }
         if (null != attributes.groupHint) {
             values.put(NetworkAttributesContract.COLNAME_GROUPHINT, attributes.groupHint);
@@ -254,7 +256,7 @@
                 getBlob(cursor, NetworkAttributesContract.COLNAME_DNSADDRESSES);
         final int mtu = getInt(cursor, NetworkAttributesContract.COLNAME_MTU, -1);
         if (0 != assignedV4AddressInt) {
-            builder.setAssignedV4Address(NetworkUtils.intToInet4AddressHTH(assignedV4AddressInt));
+            builder.setAssignedV4Address(intToInet4AddressHTH(assignedV4AddressInt));
         }
         builder.setGroupHint(groupHint);
         if (null != dnsAddressesBlob) {
diff --git a/services/net/java/android/net/dhcp/DhcpServingParamsParcelExt.java b/services/net/java/android/net/dhcp/DhcpServingParamsParcelExt.java
index f068c3a..1fe2328 100644
--- a/services/net/java/android/net/dhcp/DhcpServingParamsParcelExt.java
+++ b/services/net/java/android/net/dhcp/DhcpServingParamsParcelExt.java
@@ -16,7 +16,7 @@
 
 package android.net.dhcp;
 
-import static android.net.NetworkUtils.inet4AddressToIntHTH;
+import static android.net.shared.Inet4AddressUtils.inet4AddressToIntHTH;
 
 import android.annotation.NonNull;
 import android.net.LinkAddress;
diff --git a/tests/net/java/android/net/NetworkUtilsTest.java b/tests/net/java/android/net/NetworkUtilsTest.java
index 3452819..ba6e0f2 100644
--- a/tests/net/java/android/net/NetworkUtilsTest.java
+++ b/tests/net/java/android/net/NetworkUtilsTest.java
@@ -16,161 +16,19 @@
 
 package android.net;
 
-import static android.net.NetworkUtils.getImplicitNetmask;
-import static android.net.NetworkUtils.inet4AddressToIntHTH;
-import static android.net.NetworkUtils.inet4AddressToIntHTL;
-import static android.net.NetworkUtils.intToInet4AddressHTH;
-import static android.net.NetworkUtils.intToInet4AddressHTL;
-import static android.net.NetworkUtils.netmaskToPrefixLength;
-import static android.net.NetworkUtils.prefixLengthToV4NetmaskIntHTH;
-import static android.net.NetworkUtils.prefixLengthToV4NetmaskIntHTL;
-import static android.net.NetworkUtils.getBroadcastAddress;
-import static android.net.NetworkUtils.getPrefixMaskAsInet4Address;
-
 import static junit.framework.Assert.assertEquals;
 
-import static org.junit.Assert.fail;
-
 import android.support.test.runner.AndroidJUnit4;
 
-import java.math.BigInteger;
-import java.net.Inet4Address;
-import java.net.InetAddress;
-import java.util.TreeSet;
-
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
+import java.math.BigInteger;
+import java.util.TreeSet;
+
 @RunWith(AndroidJUnit4.class)
 @android.support.test.filters.SmallTest
 public class NetworkUtilsTest {
-
-    private InetAddress Address(String addr) {
-        return InetAddress.parseNumericAddress(addr);
-    }
-
-    private Inet4Address IPv4Address(String addr) {
-        return (Inet4Address) Address(addr);
-    }
-
-    @Test
-    public void testGetImplicitNetmask() {
-        assertEquals(8, getImplicitNetmask(IPv4Address("4.2.2.2")));
-        assertEquals(8, getImplicitNetmask(IPv4Address("10.5.6.7")));
-        assertEquals(16, getImplicitNetmask(IPv4Address("173.194.72.105")));
-        assertEquals(16, getImplicitNetmask(IPv4Address("172.23.68.145")));
-        assertEquals(24, getImplicitNetmask(IPv4Address("192.0.2.1")));
-        assertEquals(24, getImplicitNetmask(IPv4Address("192.168.5.1")));
-        assertEquals(32, getImplicitNetmask(IPv4Address("224.0.0.1")));
-        assertEquals(32, getImplicitNetmask(IPv4Address("255.6.7.8")));
-    }
-
-    private void assertInvalidNetworkMask(Inet4Address addr) {
-        try {
-            netmaskToPrefixLength(addr);
-            fail("Invalid netmask " + addr.getHostAddress() + " did not cause exception");
-        } catch (IllegalArgumentException expected) {
-        }
-    }
-
-    @Test
-    public void testInet4AddressToIntHTL() {
-        assertEquals(0, inet4AddressToIntHTL(IPv4Address("0.0.0.0")));
-        assertEquals(0x000080ff, inet4AddressToIntHTL(IPv4Address("255.128.0.0")));
-        assertEquals(0x0080ff0a, inet4AddressToIntHTL(IPv4Address("10.255.128.0")));
-        assertEquals(0x00feff0a, inet4AddressToIntHTL(IPv4Address("10.255.254.0")));
-        assertEquals(0xfeffa8c0, inet4AddressToIntHTL(IPv4Address("192.168.255.254")));
-        assertEquals(0xffffa8c0, inet4AddressToIntHTL(IPv4Address("192.168.255.255")));
-    }
-
-    @Test
-    public void testIntToInet4AddressHTL() {
-        assertEquals(IPv4Address("0.0.0.0"), intToInet4AddressHTL(0));
-        assertEquals(IPv4Address("255.128.0.0"), intToInet4AddressHTL(0x000080ff));
-        assertEquals(IPv4Address("10.255.128.0"), intToInet4AddressHTL(0x0080ff0a));
-        assertEquals(IPv4Address("10.255.254.0"), intToInet4AddressHTL(0x00feff0a));
-        assertEquals(IPv4Address("192.168.255.254"), intToInet4AddressHTL(0xfeffa8c0));
-        assertEquals(IPv4Address("192.168.255.255"), intToInet4AddressHTL(0xffffa8c0));
-    }
-
-    @Test
-    public void testInet4AddressToIntHTH() {
-        assertEquals(0, inet4AddressToIntHTH(IPv4Address("0.0.0.0")));
-        assertEquals(0xff800000, inet4AddressToIntHTH(IPv4Address("255.128.0.0")));
-        assertEquals(0x0aff8000, inet4AddressToIntHTH(IPv4Address("10.255.128.0")));
-        assertEquals(0x0afffe00, inet4AddressToIntHTH(IPv4Address("10.255.254.0")));
-        assertEquals(0xc0a8fffe, inet4AddressToIntHTH(IPv4Address("192.168.255.254")));
-        assertEquals(0xc0a8ffff, inet4AddressToIntHTH(IPv4Address("192.168.255.255")));
-    }
-
-    @Test
-    public void testIntToInet4AddressHTH() {
-        assertEquals(IPv4Address("0.0.0.0"), intToInet4AddressHTH(0));
-        assertEquals(IPv4Address("255.128.0.0"), intToInet4AddressHTH(0xff800000));
-        assertEquals(IPv4Address("10.255.128.0"), intToInet4AddressHTH(0x0aff8000));
-        assertEquals(IPv4Address("10.255.254.0"), intToInet4AddressHTH(0x0afffe00));
-        assertEquals(IPv4Address("192.168.255.254"), intToInet4AddressHTH(0xc0a8fffe));
-        assertEquals(IPv4Address("192.168.255.255"), intToInet4AddressHTH(0xc0a8ffff));
-    }
-
-    @Test
-    public void testNetmaskToPrefixLength() {
-        assertEquals(0, netmaskToPrefixLength(IPv4Address("0.0.0.0")));
-        assertEquals(9, netmaskToPrefixLength(IPv4Address("255.128.0.0")));
-        assertEquals(17, netmaskToPrefixLength(IPv4Address("255.255.128.0")));
-        assertEquals(23, netmaskToPrefixLength(IPv4Address("255.255.254.0")));
-        assertEquals(31, netmaskToPrefixLength(IPv4Address("255.255.255.254")));
-        assertEquals(32, netmaskToPrefixLength(IPv4Address("255.255.255.255")));
-
-        assertInvalidNetworkMask(IPv4Address("0.0.0.1"));
-        assertInvalidNetworkMask(IPv4Address("255.255.255.253"));
-        assertInvalidNetworkMask(IPv4Address("255.255.0.255"));
-    }
-
-    @Test
-    public void testPrefixLengthToV4NetmaskIntHTL() {
-        assertEquals(0, prefixLengthToV4NetmaskIntHTL(0));
-        assertEquals(0x000080ff /* 255.128.0.0 */, prefixLengthToV4NetmaskIntHTL(9));
-        assertEquals(0x0080ffff /* 255.255.128.0 */, prefixLengthToV4NetmaskIntHTL(17));
-        assertEquals(0x00feffff /* 255.255.254.0 */, prefixLengthToV4NetmaskIntHTL(23));
-        assertEquals(0xfeffffff /* 255.255.255.254 */, prefixLengthToV4NetmaskIntHTL(31));
-        assertEquals(0xffffffff /* 255.255.255.255 */, prefixLengthToV4NetmaskIntHTL(32));
-    }
-
-    @Test
-    public void testPrefixLengthToV4NetmaskIntHTH() {
-        assertEquals(0, prefixLengthToV4NetmaskIntHTH(0));
-        assertEquals(0xff800000 /* 255.128.0.0 */, prefixLengthToV4NetmaskIntHTH(9));
-        assertEquals(0xffff8000 /* 255.255.128.0 */, prefixLengthToV4NetmaskIntHTH(17));
-        assertEquals(0xfffffe00 /* 255.255.254.0 */, prefixLengthToV4NetmaskIntHTH(23));
-        assertEquals(0xfffffffe /* 255.255.255.254 */, prefixLengthToV4NetmaskIntHTH(31));
-        assertEquals(0xffffffff /* 255.255.255.255 */, prefixLengthToV4NetmaskIntHTH(32));
-    }
-
-    @Test(expected = IllegalArgumentException.class)
-    public void testPrefixLengthToV4NetmaskIntHTH_NegativeLength() {
-        prefixLengthToV4NetmaskIntHTH(-1);
-    }
-
-    @Test(expected = IllegalArgumentException.class)
-    public void testPrefixLengthToV4NetmaskIntHTH_LengthTooLarge() {
-        prefixLengthToV4NetmaskIntHTH(33);
-    }
-
-    private void checkAddressMasking(String expectedAddr, String addr, int prefixLength) {
-        final int prefix = prefixLengthToV4NetmaskIntHTH(prefixLength);
-        final int addrInt = inet4AddressToIntHTH(IPv4Address(addr));
-        assertEquals(IPv4Address(expectedAddr), intToInet4AddressHTH(prefix & addrInt));
-    }
-
-    @Test
-    public void testPrefixLengthToV4NetmaskIntHTH_MaskAddr() {
-        checkAddressMasking("192.168.0.0", "192.168.128.1", 16);
-        checkAddressMasking("255.240.0.0", "255.255.255.255", 12);
-        checkAddressMasking("255.255.255.255", "255.255.255.255", 32);
-        checkAddressMasking("0.0.0.0", "255.255.255.255", 0);
-    }
-
     @Test
     public void testRoutedIPv4AddressCount() {
         final TreeSet<IpPrefix> set = new TreeSet<>(IpPrefix.lengthComparator());
@@ -267,44 +125,4 @@
         assertEquals(BigInteger.valueOf(7l - 4 + 4 + 16 + 65536),
                 NetworkUtils.routedIPv6AddressCount(set));
     }
-
-    @Test
-    public void testGetPrefixMaskAsAddress() {
-        assertEquals("255.255.240.0", getPrefixMaskAsInet4Address(20).getHostAddress());
-        assertEquals("255.0.0.0", getPrefixMaskAsInet4Address(8).getHostAddress());
-        assertEquals("0.0.0.0", getPrefixMaskAsInet4Address(0).getHostAddress());
-        assertEquals("255.255.255.255", getPrefixMaskAsInet4Address(32).getHostAddress());
-    }
-
-    @Test(expected = IllegalArgumentException.class)
-    public void testGetPrefixMaskAsAddress_PrefixTooLarge() {
-        getPrefixMaskAsInet4Address(33);
-    }
-
-    @Test(expected = IllegalArgumentException.class)
-    public void testGetPrefixMaskAsAddress_NegativePrefix() {
-        getPrefixMaskAsInet4Address(-1);
-    }
-
-    @Test
-    public void testGetBroadcastAddress() {
-        assertEquals("192.168.15.255",
-                getBroadcastAddress(IPv4Address("192.168.0.123"), 20).getHostAddress());
-        assertEquals("192.255.255.255",
-                getBroadcastAddress(IPv4Address("192.168.0.123"), 8).getHostAddress());
-        assertEquals("192.168.0.123",
-                getBroadcastAddress(IPv4Address("192.168.0.123"), 32).getHostAddress());
-        assertEquals("255.255.255.255",
-                getBroadcastAddress(IPv4Address("192.168.0.123"), 0).getHostAddress());
-    }
-
-    @Test(expected = IllegalArgumentException.class)
-    public void testGetBroadcastAddress_PrefixTooLarge() {
-        getBroadcastAddress(IPv4Address("192.168.0.123"), 33);
-    }
-
-    @Test(expected = IllegalArgumentException.class)
-    public void testGetBroadcastAddress_NegativePrefix() {
-        getBroadcastAddress(IPv4Address("192.168.0.123"), -1);
-    }
 }
diff --git a/tests/net/java/android/net/ip/IpServerTest.java b/tests/net/java/android/net/ip/IpServerTest.java
index 80aac04..f7542a7 100644
--- a/tests/net/java/android/net/ip/IpServerTest.java
+++ b/tests/net/java/android/net/ip/IpServerTest.java
@@ -22,11 +22,11 @@
 import static android.net.ConnectivityManager.TETHER_ERROR_ENABLE_NAT_ERROR;
 import static android.net.ConnectivityManager.TETHER_ERROR_NO_ERROR;
 import static android.net.ConnectivityManager.TETHER_ERROR_TETHER_IFACE_ERROR;
-import static android.net.NetworkUtils.intToInet4AddressHTH;
 import static android.net.dhcp.IDhcpServer.STATUS_SUCCESS;
 import static android.net.ip.IpServer.STATE_AVAILABLE;
 import static android.net.ip.IpServer.STATE_TETHERED;
 import static android.net.ip.IpServer.STATE_UNAVAILABLE;
+import static android.net.shared.Inet4AddressUtils.intToInet4AddressHTH;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
diff --git a/tests/net/java/android/net/shared/Inet4AddressUtilsTest.java b/tests/net/java/android/net/shared/Inet4AddressUtilsTest.java
new file mode 100644
index 0000000..6da8514
--- /dev/null
+++ b/tests/net/java/android/net/shared/Inet4AddressUtilsTest.java
@@ -0,0 +1,209 @@
+/*
+ * 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.shared;
+
+import static android.net.shared.Inet4AddressUtils.getBroadcastAddress;
+import static android.net.shared.Inet4AddressUtils.getImplicitNetmask;
+import static android.net.shared.Inet4AddressUtils.getPrefixMaskAsInet4Address;
+import static android.net.shared.Inet4AddressUtils.inet4AddressToIntHTH;
+import static android.net.shared.Inet4AddressUtils.inet4AddressToIntHTL;
+import static android.net.shared.Inet4AddressUtils.intToInet4AddressHTH;
+import static android.net.shared.Inet4AddressUtils.intToInet4AddressHTL;
+import static android.net.shared.Inet4AddressUtils.netmaskToPrefixLength;
+import static android.net.shared.Inet4AddressUtils.prefixLengthToV4NetmaskIntHTH;
+import static android.net.shared.Inet4AddressUtils.prefixLengthToV4NetmaskIntHTL;
+
+import static junit.framework.Assert.assertEquals;
+
+import static org.junit.Assert.fail;
+
+import android.net.InetAddresses;
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.net.Inet4Address;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class Inet4AddressUtilsTest {
+
+    @Test
+    public void testInet4AddressToIntHTL() {
+        assertEquals(0, inet4AddressToIntHTL(ipv4Address("0.0.0.0")));
+        assertEquals(0x000080ff, inet4AddressToIntHTL(ipv4Address("255.128.0.0")));
+        assertEquals(0x0080ff0a, inet4AddressToIntHTL(ipv4Address("10.255.128.0")));
+        assertEquals(0x00feff0a, inet4AddressToIntHTL(ipv4Address("10.255.254.0")));
+        assertEquals(0xfeffa8c0, inet4AddressToIntHTL(ipv4Address("192.168.255.254")));
+        assertEquals(0xffffa8c0, inet4AddressToIntHTL(ipv4Address("192.168.255.255")));
+    }
+
+    @Test
+    public void testIntToInet4AddressHTL() {
+        assertEquals(ipv4Address("0.0.0.0"), intToInet4AddressHTL(0));
+        assertEquals(ipv4Address("255.128.0.0"), intToInet4AddressHTL(0x000080ff));
+        assertEquals(ipv4Address("10.255.128.0"), intToInet4AddressHTL(0x0080ff0a));
+        assertEquals(ipv4Address("10.255.254.0"), intToInet4AddressHTL(0x00feff0a));
+        assertEquals(ipv4Address("192.168.255.254"), intToInet4AddressHTL(0xfeffa8c0));
+        assertEquals(ipv4Address("192.168.255.255"), intToInet4AddressHTL(0xffffa8c0));
+    }
+
+    @Test
+    public void testInet4AddressToIntHTH() {
+        assertEquals(0, inet4AddressToIntHTH(ipv4Address("0.0.0.0")));
+        assertEquals(0xff800000, inet4AddressToIntHTH(ipv4Address("255.128.0.0")));
+        assertEquals(0x0aff8000, inet4AddressToIntHTH(ipv4Address("10.255.128.0")));
+        assertEquals(0x0afffe00, inet4AddressToIntHTH(ipv4Address("10.255.254.0")));
+        assertEquals(0xc0a8fffe, inet4AddressToIntHTH(ipv4Address("192.168.255.254")));
+        assertEquals(0xc0a8ffff, inet4AddressToIntHTH(ipv4Address("192.168.255.255")));
+    }
+
+    @Test
+    public void testIntToInet4AddressHTH() {
+        assertEquals(ipv4Address("0.0.0.0"), intToInet4AddressHTH(0));
+        assertEquals(ipv4Address("255.128.0.0"), intToInet4AddressHTH(0xff800000));
+        assertEquals(ipv4Address("10.255.128.0"), intToInet4AddressHTH(0x0aff8000));
+        assertEquals(ipv4Address("10.255.254.0"), intToInet4AddressHTH(0x0afffe00));
+        assertEquals(ipv4Address("192.168.255.254"), intToInet4AddressHTH(0xc0a8fffe));
+        assertEquals(ipv4Address("192.168.255.255"), intToInet4AddressHTH(0xc0a8ffff));
+    }
+
+
+    @Test
+    public void testPrefixLengthToV4NetmaskIntHTL() {
+        assertEquals(0, prefixLengthToV4NetmaskIntHTL(0));
+        assertEquals(0x000080ff /* 255.128.0.0 */, prefixLengthToV4NetmaskIntHTL(9));
+        assertEquals(0x0080ffff /* 255.255.128.0 */, prefixLengthToV4NetmaskIntHTL(17));
+        assertEquals(0x00feffff /* 255.255.254.0 */, prefixLengthToV4NetmaskIntHTL(23));
+        assertEquals(0xfeffffff /* 255.255.255.254 */, prefixLengthToV4NetmaskIntHTL(31));
+        assertEquals(0xffffffff /* 255.255.255.255 */, prefixLengthToV4NetmaskIntHTL(32));
+    }
+
+    @Test
+    public void testPrefixLengthToV4NetmaskIntHTH() {
+        assertEquals(0, prefixLengthToV4NetmaskIntHTH(0));
+        assertEquals(0xff800000 /* 255.128.0.0 */, prefixLengthToV4NetmaskIntHTH(9));
+        assertEquals(0xffff8000 /* 255.255.128.0 */, prefixLengthToV4NetmaskIntHTH(17));
+        assertEquals(0xfffffe00 /* 255.255.254.0 */, prefixLengthToV4NetmaskIntHTH(23));
+        assertEquals(0xfffffffe /* 255.255.255.254 */, prefixLengthToV4NetmaskIntHTH(31));
+        assertEquals(0xffffffff /* 255.255.255.255 */, prefixLengthToV4NetmaskIntHTH(32));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testPrefixLengthToV4NetmaskIntHTH_NegativeLength() {
+        prefixLengthToV4NetmaskIntHTH(-1);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testPrefixLengthToV4NetmaskIntHTH_LengthTooLarge() {
+        prefixLengthToV4NetmaskIntHTH(33);
+    }
+
+    private void checkAddressMasking(String expectedAddr, String addr, int prefixLength) {
+        final int prefix = prefixLengthToV4NetmaskIntHTH(prefixLength);
+        final int addrInt = inet4AddressToIntHTH(ipv4Address(addr));
+        assertEquals(ipv4Address(expectedAddr), intToInet4AddressHTH(prefix & addrInt));
+    }
+
+    @Test
+    public void testPrefixLengthToV4NetmaskIntHTH_MaskAddr() {
+        checkAddressMasking("192.168.0.0", "192.168.128.1", 16);
+        checkAddressMasking("255.240.0.0", "255.255.255.255", 12);
+        checkAddressMasking("255.255.255.255", "255.255.255.255", 32);
+        checkAddressMasking("0.0.0.0", "255.255.255.255", 0);
+    }
+
+    @Test
+    public void testGetImplicitNetmask() {
+        assertEquals(8, getImplicitNetmask(ipv4Address("4.2.2.2")));
+        assertEquals(8, getImplicitNetmask(ipv4Address("10.5.6.7")));
+        assertEquals(16, getImplicitNetmask(ipv4Address("173.194.72.105")));
+        assertEquals(16, getImplicitNetmask(ipv4Address("172.23.68.145")));
+        assertEquals(24, getImplicitNetmask(ipv4Address("192.0.2.1")));
+        assertEquals(24, getImplicitNetmask(ipv4Address("192.168.5.1")));
+        assertEquals(32, getImplicitNetmask(ipv4Address("224.0.0.1")));
+        assertEquals(32, getImplicitNetmask(ipv4Address("255.6.7.8")));
+    }
+
+    private void assertInvalidNetworkMask(Inet4Address addr) {
+        try {
+            netmaskToPrefixLength(addr);
+            fail("Invalid netmask " + addr.getHostAddress() + " did not cause exception");
+        } catch (IllegalArgumentException expected) {
+        }
+    }
+
+    @Test
+    public void testNetmaskToPrefixLength() {
+        assertEquals(0, netmaskToPrefixLength(ipv4Address("0.0.0.0")));
+        assertEquals(9, netmaskToPrefixLength(ipv4Address("255.128.0.0")));
+        assertEquals(17, netmaskToPrefixLength(ipv4Address("255.255.128.0")));
+        assertEquals(23, netmaskToPrefixLength(ipv4Address("255.255.254.0")));
+        assertEquals(31, netmaskToPrefixLength(ipv4Address("255.255.255.254")));
+        assertEquals(32, netmaskToPrefixLength(ipv4Address("255.255.255.255")));
+
+        assertInvalidNetworkMask(ipv4Address("0.0.0.1"));
+        assertInvalidNetworkMask(ipv4Address("255.255.255.253"));
+        assertInvalidNetworkMask(ipv4Address("255.255.0.255"));
+    }
+
+    @Test
+    public void testGetPrefixMaskAsAddress() {
+        assertEquals("255.255.240.0", getPrefixMaskAsInet4Address(20).getHostAddress());
+        assertEquals("255.0.0.0", getPrefixMaskAsInet4Address(8).getHostAddress());
+        assertEquals("0.0.0.0", getPrefixMaskAsInet4Address(0).getHostAddress());
+        assertEquals("255.255.255.255", getPrefixMaskAsInet4Address(32).getHostAddress());
+    }
+
+    @Test
+    public void testGetBroadcastAddress() {
+        assertEquals("192.168.15.255",
+                getBroadcastAddress(ipv4Address("192.168.0.123"), 20).getHostAddress());
+        assertEquals("192.255.255.255",
+                getBroadcastAddress(ipv4Address("192.168.0.123"), 8).getHostAddress());
+        assertEquals("192.168.0.123",
+                getBroadcastAddress(ipv4Address("192.168.0.123"), 32).getHostAddress());
+        assertEquals("255.255.255.255",
+                getBroadcastAddress(ipv4Address("192.168.0.123"), 0).getHostAddress());
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testGetBroadcastAddress_PrefixTooLarge() {
+        getBroadcastAddress(ipv4Address("192.168.0.123"), 33);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testGetBroadcastAddress_NegativePrefix() {
+        getBroadcastAddress(ipv4Address("192.168.0.123"), -1);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testGetPrefixMaskAsAddress_PrefixTooLarge() {
+        getPrefixMaskAsInet4Address(33);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testGetPrefixMaskAsAddress_NegativePrefix() {
+        getPrefixMaskAsInet4Address(-1);
+    }
+
+    private Inet4Address ipv4Address(String addr) {
+        return (Inet4Address) InetAddresses.parseNumericAddress(addr);
+    }
+}