1 /*
2 * Copyright 2020 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the License. You may obtain a copy of the License at:
7 *
8 * https://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, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package io.netty.handler.pcap;
17
18 import io.netty.buffer.ByteBuf;
19
20 final class UDPPacket {
21
22 private static final short UDP_HEADER_SIZE = 8;
23
24 private UDPPacket() {
25 // Prevent outside initialization
26 }
27
28 /**
29 * Write UDP Packet
30 *
31 * @param byteBuf ByteBuf where Packet data will be set
32 * @param payload Payload of this Packet
33 * @param srcPort Source Port
34 * @param dstPort Destination Port
35 */
36 static void writePacket(ByteBuf byteBuf, ByteBuf payload, int srcPort, int dstPort) {
37 byteBuf.writeShort(srcPort); // Source Port
38 byteBuf.writeShort(dstPort); // Destination Port
39 byteBuf.writeShort(UDP_HEADER_SIZE + payload.readableBytes()); // UDP Header Length + Payload Length
40 byteBuf.writeShort(0x0001); // Checksum
41 byteBuf.writeBytes(payload); // Payload of Data
42 }
43 }