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 import java.io.IOException;
21 import java.io.OutputStream;
22
23 final class PcapHeaders {
24
25 /**
26 * Pcap Global Header built from:
27 * <ol>
28 * <li> magic_number </li>
29 * <li> version_major </li>
30 * <li> version_minor </li>
31 * <li> thiszone </li>
32 * <li> sigfigs </li>
33 * <li> snaplen </li>
34 * <li> network </li>
35 * </ol>
36 */
37 private static final byte[] GLOBAL_HEADER = {-95, -78, -61, -44, 0, 2, 0, 4, 0, 0,
38 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, 0, 0, 0, 1};
39
40 private PcapHeaders() {
41 // Prevent outside initialization
42 }
43
44 /**
45 * Writes the Pcap Global Header to the provided {@code OutputStream}
46 *
47 * @param outputStream OutputStream where Pcap data will be written.
48 * @throws IOException if there is an error writing to the {@code OutputStream}
49 */
50 static void writeGlobalHeader(OutputStream outputStream) throws IOException {
51 outputStream.write(GLOBAL_HEADER);
52 }
53
54 /**
55 * Write Pcap Packet Header
56 *
57 * @param byteBuf ByteBuf where we'll write header data
58 * @param ts_sec timestamp seconds
59 * @param ts_usec timestamp microseconds
60 * @param incl_len number of octets of packet saved in file
61 * @param orig_len actual length of packet
62 */
63 static void writePacketHeader(ByteBuf byteBuf, int ts_sec, int ts_usec, int incl_len, int orig_len) {
64 byteBuf.writeInt(ts_sec);
65 byteBuf.writeInt(ts_usec);
66 byteBuf.writeInt(incl_len);
67 byteBuf.writeInt(orig_len);
68 }
69 }