-
Notifications
You must be signed in to change notification settings - Fork 573
/
Packetizer.java
84 lines (69 loc) · 2.91 KB
/
Packetizer.java
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
/*
* Copyright (C) 2017 Genymobile
*
* 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 com.genymobile.gnirehtet.relay;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;
/**
* Convert from level 5 to level 3 by appending correct IP and transport headers.
*/
public class Packetizer {
private final ByteBuffer buffer = ByteBuffer.allocate(IPv4Packet.MAX_PACKET_LENGTH);
private final ByteBuffer payloadBuffer;
private final IPv4Header responseIPv4Header;
private final TransportHeader responseTransportHeader;
public Packetizer(IPv4Header ipv4Header, TransportHeader transportHeader) {
responseIPv4Header = ipv4Header.copyTo(buffer);
responseTransportHeader = transportHeader.copyTo(buffer);
payloadBuffer = buffer.slice();
}
public IPv4Header getResponseIPv4Header() {
return responseIPv4Header;
}
public TransportHeader getResponseTransportHeader() {
return responseTransportHeader;
}
public IPv4Packet packetizeEmptyPayload() {
payloadBuffer.limit(0).position(0);
return inflate();
}
public IPv4Packet packetize(ReadableByteChannel channel, int maxChunkSize) throws IOException {
payloadBuffer.limit(maxChunkSize).position(0);
int payloadLength = channel.read(payloadBuffer);
if (payloadLength == -1) {
return null;
}
payloadBuffer.flip();
return inflate();
}
public IPv4Packet packetize(ReadableByteChannel channel) throws IOException {
return packetize(channel, payloadBuffer.capacity());
}
private IPv4Packet inflate() {
int payloadLength = payloadBuffer.remaining();
buffer.limit(payloadBuffer.arrayOffset() + payloadBuffer.limit()).position(0);
int ipv4HeaderLength = responseIPv4Header.getHeaderLength();
int transportHeaderLength = responseTransportHeader.getHeaderLength();
int totalLength = ipv4HeaderLength + transportHeaderLength + payloadLength;
responseIPv4Header.setTotalLength(totalLength);
responseTransportHeader.setPayloadLength(payloadLength);
// In order to avoid copies, buffer is shared with this IPv4Packet instance that is returned.
// Don't use it after another call to packetize()!
IPv4Packet packet = new IPv4Packet(buffer);
packet.computeChecksums();
return packet;
}
}