/* * Copyright (C) 2014 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.os.Parcel; import android.os.Parcelable; import android.util.Pair; import java.net.InetAddress; import java.net.UnknownHostException; import java.util.Arrays; /** * This class represents an IP prefix, i.e., a contiguous block of IP addresses aligned on a * power of two boundary (also known as an "IP subnet"). A prefix is specified by two pieces of * information: * * * * For example, the prefix 192.0.2.0/24 covers the 256 IPv4 addresses from * 192.0.2.0 to 192.0.2.255, inclusive, and the prefix * 2001:db8:1:2 covers the 2^64 IPv6 addresses from 2001:db8:1:2:: to * 2001:db8:1:2:ffff:ffff:ffff:ffff, inclusive. * * Objects of this class are immutable. */ public final class IpPrefix implements Parcelable { private final byte[] address; // network byte order private final int prefixLength; private void checkAndMaskAddressAndPrefixLength() { if (address.length != 4 && address.length != 16) { throw new IllegalArgumentException( "IpPrefix has " + address.length + " bytes which is neither 4 nor 16"); } NetworkUtils.maskRawAddress(address, prefixLength); } /** * Constructs a new {@code IpPrefix} from a byte array containing an IPv4 or IPv6 address in * network byte order and a prefix length. Silently truncates the address to the prefix length, * so for example {@code 192.0.2.1/24} is silently converted to {@code 192.0.2.0/24}. * * @param address the IP address. Must be non-null and exactly 4 or 16 bytes long. * @param prefixLength the prefix length. Must be >= 0 and <= (32 or 128) (IPv4 or IPv6). * * @hide */ public IpPrefix(byte[] address, int prefixLength) { this.address = address.clone(); this.prefixLength = prefixLength; checkAndMaskAddressAndPrefixLength(); } /** * Constructs a new {@code IpPrefix} from an IPv4 or IPv6 address and a prefix length. Silently * truncates the address to the prefix length, so for example {@code 192.0.2.1/24} is silently * converted to {@code 192.0.2.0/24}. * * @param address the IP address. Must be non-null. * @param prefixLength the prefix length. Must be >= 0 and <= (32 or 128) (IPv4 or IPv6). * @hide */ public IpPrefix(InetAddress address, int prefixLength) { // We don't reuse the (byte[], int) constructor because it calls clone() on the byte array, // which is unnecessary because getAddress() already returns a clone. this.address = address.getAddress(); this.prefixLength = prefixLength; checkAndMaskAddressAndPrefixLength(); } /** * Constructs a new IpPrefix from a string such as "192.0.2.1/24" or "2001:db8::1/64". * Silently truncates the address to the prefix length, so for example {@code 192.0.2.1/24} * is silently converted to {@code 192.0.2.0/24}. * * @param prefix the prefix to parse * * @hide */ public IpPrefix(String prefix) { // We don't reuse the (InetAddress, int) constructor because "error: call to this must be // first statement in constructor". We could factor out setting the member variables to an // init() method, but if we did, then we'd have to make the members non-final, or "error: // cannot assign a value to final variable address". So we just duplicate the code here. Pair ipAndMask = NetworkUtils.parseIpAndMask(prefix); this.address = ipAndMask.first.getAddress(); this.prefixLength = ipAndMask.second; checkAndMaskAddressAndPrefixLength(); } /** * Compares this {@code IpPrefix} object against the specified object in {@code obj}. Two * objects are equal if they have the same startAddress and prefixLength. * * @param obj the object to be tested for equality. * @return {@code true} if both objects are equal, {@code false} otherwise. */ @Override public boolean equals(Object obj) { if (!(obj instanceof IpPrefix)) { return false; } IpPrefix that = (IpPrefix) obj; return Arrays.equals(this.address, that.address) && this.prefixLength == that.prefixLength; } /** * Gets the hashcode of the represented IP prefix. * * @return the appropriate hashcode value. */ @Override public int hashCode() { return Arrays.hashCode(address) + 11 * prefixLength; } /** * Returns a copy of the first IP address in the prefix. Modifying the returned object does not * change this object's contents. * * @return the address in the form of a byte array. */ public InetAddress getAddress() { try { return InetAddress.getByAddress(address); } catch (UnknownHostException e) { // Cannot happen. InetAddress.getByAddress can only throw an exception if the byte // array is the wrong length, but we check that in the constructor. return null; } } /** * Returns a copy of the IP address bytes in network order (the highest order byte is the zeroth * element). Modifying the returned array does not change this object's contents. * * @return the address in the form of a byte array. */ public byte[] getRawAddress() { return address.clone(); } /** * Returns the prefix length of this {@code IpPrefix}. * * @return the prefix length. */ public int getPrefixLength() { return prefixLength; } /** * Returns a string representation of this {@code IpPrefix}. * * @return a string such as {@code "192.0.2.0/24"} or {@code "2001:db8:1:2::/64"}. */ public String toString() { try { return InetAddress.getByAddress(address).getHostAddress() + "/" + prefixLength; } catch(UnknownHostException e) { // Cosmic rays? throw new IllegalStateException("IpPrefix with invalid address! Shouldn't happen.", e); } } /** * Implement the Parcelable interface. */ public int describeContents() { return 0; } /** * Implement the Parcelable interface. */ public void writeToParcel(Parcel dest, int flags) { dest.writeByteArray(address); dest.writeInt(prefixLength); } /** * Implement the Parcelable interface. */ public static final Creator CREATOR = new Creator() { public IpPrefix createFromParcel(Parcel in) { byte[] address = in.createByteArray(); int prefixLength = in.readInt(); return new IpPrefix(address, prefixLength); } public IpPrefix[] newArray(int size) { return new IpPrefix[size]; } }; }