Add two utility methods for IPv4 netmasks. (e5ef28f5) · Commits · e / os / android_frameworks_base

core/java/android/net/NetworkUtils.java

+35 −0

Original line number	Diff line number	Diff line
		@@ -229,6 +229,25 @@ public class NetworkUtils {
		return Integer.bitCount(netmask);
		}

		/**
		* 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 = 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;
		}


		/**
		* Create an InetAddress from a string where the string must be a standard
		* representation of a V4 or V6 address. Avoids doing a DNS lookup on failure
		@@ -308,6 +327,22 @@ public class NetworkUtils {
		return netPart;
		}

		/**
		* 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.
		}
		}

		/**
		* Utility method to parse strings such as "192.0.2.5/24" or "2001:db8::cafe:d00d/64".
		* @hide

core/tests/coretests/src/android/net/NetworkUtilsTest.java

0 → 100644

+70 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2015 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		package android.net;

		import android.net.NetworkUtils;
		import android.test.suitebuilder.annotation.SmallTest;

		import java.net.Inet4Address;
		import java.net.InetAddress;

		import junit.framework.TestCase;

		public class NetworkUtilsTest extends TestCase {

		private InetAddress Address(String addr) {
		return InetAddress.parseNumericAddress(addr);
		}

		private Inet4Address IPv4Address(String addr) {
		return (Inet4Address) Address(addr);
		}

		@SmallTest
		public void testGetImplicitNetmask() {
		assertEquals(8, NetworkUtils.getImplicitNetmask(IPv4Address("4.2.2.2")));
		assertEquals(8, NetworkUtils.getImplicitNetmask(IPv4Address("10.5.6.7")));
		assertEquals(16, NetworkUtils.getImplicitNetmask(IPv4Address("173.194.72.105")));
		assertEquals(16, NetworkUtils.getImplicitNetmask(IPv4Address("172.23.68.145")));
		assertEquals(24, NetworkUtils.getImplicitNetmask(IPv4Address("192.0.2.1")));
		assertEquals(24, NetworkUtils.getImplicitNetmask(IPv4Address("192.168.5.1")));
		assertEquals(32, NetworkUtils.getImplicitNetmask(IPv4Address("224.0.0.1")));
		assertEquals(32, NetworkUtils.getImplicitNetmask(IPv4Address("255.6.7.8")));
		}

		private void assertInvalidNetworkMask(Inet4Address addr) {
		try {
		NetworkUtils.netmaskToPrefixLength(addr);
		fail("Invalid netmask " + addr.getHostAddress() + " did not cause exception");
		} catch (IllegalArgumentException expected) {
		}
		}

		@SmallTest
		public void testNetmaskToPrefixLength() {
		assertEquals(0, NetworkUtils.netmaskToPrefixLength(IPv4Address("0.0.0.0")));
		assertEquals(9, NetworkUtils.netmaskToPrefixLength(IPv4Address("255.128.0.0")));
		assertEquals(17, NetworkUtils.netmaskToPrefixLength(IPv4Address("255.255.128.0")));
		assertEquals(23, NetworkUtils.netmaskToPrefixLength(IPv4Address("255.255.254.0")));
		assertEquals(31, NetworkUtils.netmaskToPrefixLength(IPv4Address("255.255.255.254")));
		assertEquals(32, NetworkUtils.netmaskToPrefixLength(IPv4Address("255.255.255.255")));

		assertInvalidNetworkMask(IPv4Address("0.0.0.1"));
		assertInvalidNetworkMask(IPv4Address("255.255.255.253"));
		assertInvalidNetworkMask(IPv4Address("255.255.0.255"));
		}
		}