1 /* 2 * Copyright (C) 2024 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.net.module.util.netlink; 18 19 import android.net.IpPrefix; 20 import android.system.OsConstants; 21 22 import androidx.annotation.NonNull; 23 import androidx.annotation.Nullable; 24 import androidx.annotation.VisibleForTesting; 25 26 import java.net.Inet6Address; 27 import java.nio.ByteBuffer; 28 29 /** 30 * A NetlinkMessage subclass for rtnetlink address messages. 31 * 32 * RtNetlinkPrefixMessage.parse() must be called with a ByteBuffer that contains exactly one 33 * netlink message. 34 * 35 * see also: 36 * 37 * include/uapi/linux/rtnetlink.h 38 * 39 * @hide 40 */ 41 public class RtNetlinkPrefixMessage extends NetlinkMessage { 42 public static final short PREFIX_ADDRESS = 1; 43 public static final short PREFIX_CACHEINFO = 2; 44 45 @NonNull 46 private StructPrefixMsg mPrefixmsg; 47 @NonNull 48 private IpPrefix mPrefix; 49 private long mPreferredLifetime; 50 private long mValidLifetime; 51 52 @VisibleForTesting RtNetlinkPrefixMessage(@onNull final StructNlMsgHdr header, @NonNull final StructPrefixMsg prefixmsg, @NonNull final IpPrefix prefix, long preferred, long valid)53 public RtNetlinkPrefixMessage(@NonNull final StructNlMsgHdr header, 54 @NonNull final StructPrefixMsg prefixmsg, 55 @NonNull final IpPrefix prefix, 56 long preferred, long valid) { 57 super(header); 58 mPrefixmsg = prefixmsg; 59 mPrefix = prefix; 60 mPreferredLifetime = preferred; 61 mValidLifetime = valid; 62 } 63 RtNetlinkPrefixMessage(@onNull StructNlMsgHdr header)64 private RtNetlinkPrefixMessage(@NonNull StructNlMsgHdr header) { 65 this(header, null, null, 0 /* preferredLifetime */, 0 /* validLifetime */); 66 } 67 68 @NonNull getPrefixMsg()69 public StructPrefixMsg getPrefixMsg() { 70 return mPrefixmsg; 71 } 72 73 @NonNull getPrefix()74 public IpPrefix getPrefix() { 75 return mPrefix; 76 } 77 getPreferredLifetime()78 public long getPreferredLifetime() { 79 return mPreferredLifetime; 80 } 81 getValidLifetime()82 public long getValidLifetime() { 83 return mValidLifetime; 84 } 85 86 /** 87 * Parse rtnetlink prefix message from {@link ByteBuffer}. This method must be called with a 88 * ByteBuffer that contains exactly one netlink message. 89 * 90 * RTM_NEWPREFIX Message Format: 91 * +----------+- - -+-------------+- - -+---------------------+-----------------------+ 92 * | nlmsghdr | Pad | prefixmsg | Pad | PREFIX_ADDRESS attr | PREFIX_CACHEINFO attr | 93 * +----------+- - -+-------------+- - -+---------------------+-----------------------+ 94 * 95 * @param header netlink message header. 96 * @param byteBuffer the ByteBuffer instance that wraps the raw netlink message bytes. 97 */ 98 @Nullable parse(@onNull final StructNlMsgHdr header, @NonNull final ByteBuffer byteBuffer)99 public static RtNetlinkPrefixMessage parse(@NonNull final StructNlMsgHdr header, 100 @NonNull final ByteBuffer byteBuffer) { 101 try { 102 final RtNetlinkPrefixMessage msg = new RtNetlinkPrefixMessage(header); 103 msg.mPrefixmsg = StructPrefixMsg.parse(byteBuffer); 104 105 // PREFIX_ADDRESS 106 final int baseOffset = byteBuffer.position(); 107 StructNlAttr nlAttr = StructNlAttr.findNextAttrOfType(PREFIX_ADDRESS, byteBuffer); 108 if (nlAttr == null) return null; 109 final Inet6Address addr = (Inet6Address) nlAttr.getValueAsInetAddress(); 110 if (addr == null) return null; 111 msg.mPrefix = new IpPrefix(addr, msg.mPrefixmsg.prefix_len); 112 113 // PREFIX_CACHEINFO 114 byteBuffer.position(baseOffset); 115 nlAttr = StructNlAttr.findNextAttrOfType(PREFIX_CACHEINFO, byteBuffer); 116 if (nlAttr == null) return null; 117 final ByteBuffer buffer = nlAttr.getValueAsByteBuffer(); 118 if (buffer == null) return null; 119 final StructPrefixCacheInfo cacheinfo = StructPrefixCacheInfo.parse(buffer); 120 msg.mPreferredLifetime = cacheinfo.preferred_time; 121 msg.mValidLifetime = cacheinfo.valid_time; 122 123 return msg; 124 } catch (IllegalArgumentException e) { 125 return null; 126 } 127 } 128 129 /** 130 * Write a rtnetlink prefix message to {@link ByteBuffer}. 131 */ 132 @VisibleForTesting pack(ByteBuffer byteBuffer)133 protected void pack(ByteBuffer byteBuffer) { 134 getHeader().pack(byteBuffer); 135 mPrefixmsg.pack(byteBuffer); 136 137 // PREFIX_ADDRESS attribute 138 final StructNlAttr prefixAddress = 139 new StructNlAttr(PREFIX_ADDRESS, mPrefix.getRawAddress()); 140 prefixAddress.pack(byteBuffer); 141 142 // PREFIX_CACHEINFO attribute 143 final StructPrefixCacheInfo cacheinfo = 144 new StructPrefixCacheInfo(mPreferredLifetime, mValidLifetime); 145 final StructNlAttr prefixCacheinfo = 146 new StructNlAttr(PREFIX_CACHEINFO, cacheinfo.writeToBytes()); 147 prefixCacheinfo.pack(byteBuffer); 148 } 149 150 @Override toString()151 public String toString() { 152 return "RtNetlinkPrefixMessage{ " 153 + "nlmsghdr{" + mHeader.toString(OsConstants.NETLINK_ROUTE) + "}, " 154 + "prefixmsg{" + mPrefixmsg.toString() + "}, " 155 + "IP Prefix{" + mPrefix + "}, " 156 + "preferred lifetime{" + mPreferredLifetime + "}, " 157 + "valid lifetime{" + mValidLifetime + "} " 158 + "}"; 159 } 160 } 161