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
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
|
/*
* 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.SocketKeepalive.ERROR_INVALID_IP_ADDRESS;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.net.SocketKeepalive.InvalidPacketException;
import android.net.util.IpUtils;
import android.os.Parcel;
import android.os.Parcelable;
import android.system.OsConstants;
import java.net.Inet4Address;
import java.net.InetAddress;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.Objects;
/**
* Represents the actual tcp keep alive packets which will be used for hardware offload.
* @hide
*/
public class TcpKeepalivePacketData extends KeepalivePacketData implements Parcelable {
private static final String TAG = "TcpKeepalivePacketData";
/** TCP sequence number. */
public final int tcpSeq;
/** TCP ACK number. */
public final int tcpAck;
/** TCP RCV window. */
public final int tcpWnd;
/** TCP RCV window scale. */
public final int tcpWndScale;
private static final int IPV4_HEADER_LENGTH = 20;
private static final int IPV6_HEADER_LENGTH = 40;
private static final int TCP_HEADER_LENGTH = 20;
// This should only be constructed via static factory methods, such as
// tcpKeepalivePacket.
private TcpKeepalivePacketData(TcpSocketInfo tcpDetails, byte[] data)
throws InvalidPacketException {
super(tcpDetails.srcAddress, tcpDetails.srcPort, tcpDetails.dstAddress,
tcpDetails.dstPort, data);
tcpSeq = tcpDetails.seq;
tcpAck = tcpDetails.ack;
// In the packet, the window is shifted right by the window scale.
tcpWnd = tcpDetails.rcvWnd;
tcpWndScale = tcpDetails.rcvWndScale;
}
/**
* Factory method to create tcp keepalive packet structure.
*/
public static TcpKeepalivePacketData tcpKeepalivePacket(
TcpSocketInfo tcpDetails) throws InvalidPacketException {
final byte[] packet;
if ((tcpDetails.srcAddress instanceof Inet4Address)
&& (tcpDetails.dstAddress instanceof Inet4Address)) {
packet = buildV4Packet(tcpDetails);
} else {
// TODO: support ipv6
throw new InvalidPacketException(ERROR_INVALID_IP_ADDRESS);
}
return new TcpKeepalivePacketData(tcpDetails, packet);
}
/**
* Build ipv4 tcp keepalive packet, not including the link-layer header.
*/
// TODO : if this code is ever moved to the network stack, factorize constants with the ones
// over there.
private static byte[] buildV4Packet(TcpSocketInfo tcpDetails) {
final int length = IPV4_HEADER_LENGTH + TCP_HEADER_LENGTH;
ByteBuffer buf = ByteBuffer.allocate(length);
buf.order(ByteOrder.BIG_ENDIAN);
// IP version and TOS. TODO : fetch this from getsockopt(SOL_IP, IP_TOS)
buf.putShort((short) 0x4500);
buf.putShort((short) length);
buf.putInt(0x4000); // ID, flags=DF, offset
// TODO : fetch TTL from getsockopt(SOL_IP, IP_TTL)
buf.put((byte) 64);
buf.put((byte) OsConstants.IPPROTO_TCP);
final int ipChecksumOffset = buf.position();
buf.putShort((short) 0); // IP checksum
buf.put(tcpDetails.srcAddress.getAddress());
buf.put(tcpDetails.dstAddress.getAddress());
buf.putShort((short) tcpDetails.srcPort);
buf.putShort((short) tcpDetails.dstPort);
buf.putInt(tcpDetails.seq); // Sequence Number
buf.putInt(tcpDetails.ack); // ACK
buf.putShort((short) 0x5010); // TCP length=5, flags=ACK
buf.putShort((short) (tcpDetails.rcvWnd >> tcpDetails.rcvWndScale)); // Window size
final int tcpChecksumOffset = buf.position();
buf.putShort((short) 0); // TCP checksum
// URG is not set therefore the urgent pointer is not included
buf.putShort(ipChecksumOffset, IpUtils.ipChecksum(buf, 0));
buf.putShort(tcpChecksumOffset, IpUtils.tcpChecksum(
buf, 0, IPV4_HEADER_LENGTH, TCP_HEADER_LENGTH));
return buf.array();
}
// TODO: add buildV6Packet.
/** Represents tcp/ip information. */
// TODO: Replace TcpSocketInfo with TcpKeepalivePacketDataParcelable.
public static class TcpSocketInfo {
public final InetAddress srcAddress;
public final InetAddress dstAddress;
public final int srcPort;
public final int dstPort;
public final int seq;
public final int ack;
public final int rcvWnd;
public final int rcvWndScale;
public TcpSocketInfo(InetAddress sAddr, int sPort, InetAddress dAddr,
int dPort, int writeSeq, int readSeq, int rWnd, int rWndScale) {
srcAddress = sAddr;
dstAddress = dAddr;
srcPort = sPort;
dstPort = dPort;
seq = writeSeq;
ack = readSeq;
rcvWnd = rWnd;
rcvWndScale = rWndScale;
}
}
@Override
public boolean equals(@Nullable final Object o) {
if (!(o instanceof TcpKeepalivePacketData)) return false;
final TcpKeepalivePacketData other = (TcpKeepalivePacketData) o;
return this.srcAddress.equals(other.srcAddress)
&& this.dstAddress.equals(other.dstAddress)
&& this.srcPort == other.srcPort
&& this.dstPort == other.dstPort
&& this.tcpAck == other.tcpAck
&& this.tcpSeq == other.tcpSeq
&& this.tcpWnd == other.tcpWnd
&& this.tcpWndScale == other.tcpWndScale;
}
@Override
public int hashCode() {
return Objects.hash(srcAddress, dstAddress, srcPort, dstPort, tcpAck, tcpSeq, tcpWnd,
tcpWndScale);
}
/* Parcelable Implementation. */
/* Note that this object implements parcelable (and needs to keep doing this as it inherits
* from a class that does), but should usually be parceled as a stable parcelable using
* the toStableParcelable() and fromStableParcelable() methods.
*/
public int describeContents() {
return 0;
}
/** Write to parcel. */
public void writeToParcel(Parcel out, int flags) {
super.writeToParcel(out, flags);
out.writeInt(tcpSeq);
out.writeInt(tcpAck);
out.writeInt(tcpWnd);
out.writeInt(tcpWndScale);
}
private TcpKeepalivePacketData(Parcel in) {
super(in);
tcpSeq = in.readInt();
tcpAck = in.readInt();
tcpWnd = in.readInt();
tcpWndScale = in.readInt();
}
/** Parcelable Creator. */
public static final Parcelable.Creator<TcpKeepalivePacketData> CREATOR =
new Parcelable.Creator<TcpKeepalivePacketData>() {
public TcpKeepalivePacketData createFromParcel(Parcel in) {
return new TcpKeepalivePacketData(in);
}
public TcpKeepalivePacketData[] newArray(int size) {
return new TcpKeepalivePacketData[size];
}
};
/**
* Convert this TcpKeepalivePacketData to a TcpKeepalivePacketDataParcelable.
*/
@NonNull
public TcpKeepalivePacketDataParcelable toStableParcelable() {
final TcpKeepalivePacketDataParcelable parcel = new TcpKeepalivePacketDataParcelable();
parcel.srcAddress = srcAddress.getAddress();
parcel.srcPort = srcPort;
parcel.dstAddress = dstAddress.getAddress();
parcel.dstPort = dstPort;
parcel.seq = tcpSeq;
parcel.ack = tcpAck;
return parcel;
}
@Override
public String toString() {
return "saddr: " + srcAddress
+ " daddr: " + dstAddress
+ " sport: " + srcPort
+ " dport: " + dstPort
+ " seq: " + tcpSeq
+ " ack: " + tcpAck
+ " wnd: " + tcpWnd
+ " wndScale: " + tcpWndScale;
}
}
|
