1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
|
/*
* 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;
import static android.net.InvalidPacketException.ERROR_INVALID_IP_ADDRESS;
import static android.net.InvalidPacketException.ERROR_INVALID_PORT;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.annotation.SystemApi;
import android.os.Parcel;
import android.os.Parcelable;
import android.system.OsConstants;
import com.android.net.module.util.IpUtils;
import java.net.Inet4Address;
import java.net.InetAddress;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.Objects;
/** @hide */
@SystemApi
public final class NattKeepalivePacketData extends KeepalivePacketData implements Parcelable {
private static final int IPV4_HEADER_LENGTH = 20;
private static final int UDP_HEADER_LENGTH = 8;
// This should only be constructed via static factory methods, such as
// nattKeepalivePacket
public NattKeepalivePacketData(@NonNull InetAddress srcAddress, int srcPort,
@NonNull InetAddress dstAddress, int dstPort, @NonNull byte[] data) throws
InvalidPacketException {
super(srcAddress, srcPort, dstAddress, dstPort, data);
}
/**
* Factory method to create Nat-T keepalive packet structure.
* @hide
*/
public static NattKeepalivePacketData nattKeepalivePacket(
InetAddress srcAddress, int srcPort, InetAddress dstAddress, int dstPort)
throws InvalidPacketException {
if (!(srcAddress instanceof Inet4Address) || !(dstAddress instanceof Inet4Address)) {
throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS);
}
if (dstPort != NattSocketKeepalive.NATT_PORT) {
throw new InvalidPacketException(ERROR_INVALID_PORT);
}
int length = IPV4_HEADER_LENGTH + UDP_HEADER_LENGTH + 1;
ByteBuffer buf = ByteBuffer.allocate(length);
buf.order(ByteOrder.BIG_ENDIAN);
buf.putShort((short) 0x4500); // IP version and TOS
buf.putShort((short) length);
buf.putInt(0); // ID, flags, offset
buf.put((byte) 64); // TTL
buf.put((byte) OsConstants.IPPROTO_UDP);
int ipChecksumOffset = buf.position();
buf.putShort((short) 0); // IP checksum
buf.put(srcAddress.getAddress());
buf.put(dstAddress.getAddress());
buf.putShort((short) srcPort);
buf.putShort((short) dstPort);
buf.putShort((short) (length - 20)); // UDP length
int udpChecksumOffset = buf.position();
buf.putShort((short) 0); // UDP checksum
buf.put((byte) 0xff); // NAT-T keepalive
buf.putShort(ipChecksumOffset, IpUtils.ipChecksum(buf, 0));
buf.putShort(udpChecksumOffset, IpUtils.udpChecksum(buf, 0, IPV4_HEADER_LENGTH));
return new NattKeepalivePacketData(srcAddress, srcPort, dstAddress, dstPort, buf.array());
}
/** Parcelable Implementation */
public int describeContents() {
return 0;
}
/** Write to parcel */
public void writeToParcel(@NonNull Parcel out, int flags) {
out.writeString(getSrcAddress().getHostAddress());
out.writeString(getDstAddress().getHostAddress());
out.writeInt(getSrcPort());
out.writeInt(getDstPort());
}
/** Parcelable Creator */
public static final @NonNull Parcelable.Creator<NattKeepalivePacketData> CREATOR =
new Parcelable.Creator<NattKeepalivePacketData>() {
public NattKeepalivePacketData createFromParcel(Parcel in) {
final InetAddress srcAddress =
InetAddresses.parseNumericAddress(in.readString());
final InetAddress dstAddress =
InetAddresses.parseNumericAddress(in.readString());
final int srcPort = in.readInt();
final int dstPort = in.readInt();
try {
return NattKeepalivePacketData.nattKeepalivePacket(srcAddress, srcPort,
dstAddress, dstPort);
} catch (InvalidPacketException e) {
throw new IllegalArgumentException(
"Invalid NAT-T keepalive data: " + e.getError());
}
}
public NattKeepalivePacketData[] newArray(int size) {
return new NattKeepalivePacketData[size];
}
};
@Override
public boolean equals(@Nullable final Object o) {
if (!(o instanceof NattKeepalivePacketData)) return false;
final NattKeepalivePacketData other = (NattKeepalivePacketData) o;
final InetAddress srcAddress = getSrcAddress();
final InetAddress dstAddress = getDstAddress();
return srcAddress.equals(other.getSrcAddress())
&& dstAddress.equals(other.getDstAddress())
&& getSrcPort() == other.getSrcPort()
&& getDstPort() == other.getDstPort();
}
@Override
public int hashCode() {
return Objects.hash(getSrcAddress(), getDstAddress(), getSrcPort(), getDstPort());
}
}
|
