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

2 files changed, 186 insertions, 136 deletions

diff --git a/core/java/android/net/NetworkUtils.java b/core/java/android/net/NetworkUtils.java
index c996d01fe8e4..39db4fef78b5 100644
--- a/core/java/android/net/NetworkUtils.java
+++ b/core/java/android/net/NetworkUtils.java
@@ -21,8 +21,10 @@ import static android.system.OsConstants.AF_INET6;
 
 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.Collection;
 import java.util.Locale;
 import java.util.TreeSet;
 
-import android.system.ErrnoException;
-
 /**
  * Native methods for managing network interfaces.
  *
@@ -177,119 +177,37 @@ public class NetworkUtils {
             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);
-    }
-
-    /**
-     * 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));
+        return Inet4AddressUtils.intToInet4AddressHTL(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);
-    }
-
-    /**
-     * 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));
+        return Inet4AddressUtils.inet4AddressToIntHTL(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 @@ public class NetworkUtils {
      * @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 @@ public class NetworkUtils {
      */
     @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 @@ public class NetworkUtils {
     }
 
     /**
-     * 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 000000000000..bec0c84fa689
--- /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));
+    }
+}