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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  import io.netty.util.internal.logging.InternalLogger;
20  import io.netty.util.internal.logging.InternalLoggerFactory;
21  
22  import java.io.Closeable;
23  import java.io.IOException;
24  import java.io.OutputStream;
25  
26  final class PcapWriter implements Closeable {
27  
28      /**
29       * Logger
30       */
31      private static final InternalLogger logger = InternalLoggerFactory.getInstance(PcapWriter.class);
32  
33      private final PcapWriteHandler pcapWriteHandler;
34  
35      /**
36       * Reference declared so that we can use this as mutex in clean way.
37       */
38      private final OutputStream outputStream;
39  
40      /**
41       * This uses {@link OutputStream} for writing Pcap data.
42       *
43       * @throws IOException If {@link OutputStream#write(byte[])} throws an exception
44       */
45      PcapWriter(PcapWriteHandler pcapWriteHandler) throws IOException {
46          this.pcapWriteHandler = pcapWriteHandler;
47          outputStream = pcapWriteHandler.outputStream();
48  
49          // If OutputStream is not shared then we have to write Global Header.
50          if (!pcapWriteHandler.sharedOutputStream()) {
51              PcapHeaders.writeGlobalHeader(pcapWriteHandler.outputStream());
52          }
53      }
54  
55      /**
56       * Write Packet in Pcap OutputStream.
57       *
58       * @param packetHeaderBuf Packer Header {@link ByteBuf}
59       * @param packet          Packet
60       * @throws IOException If {@link OutputStream#write(byte[])} throws an exception
61       */
62      void writePacket(ByteBuf packetHeaderBuf, ByteBuf packet) throws IOException {
63          if (pcapWriteHandler.state() == State.CLOSED) {
64              logger.debug("Pcap Write attempted on closed PcapWriter");
65          }
66  
67          long timestamp = System.currentTimeMillis();
68  
69          PcapHeaders.writePacketHeader(
70                  packetHeaderBuf,
71                  (int) (timestamp / 1000L),
72                  (int) (timestamp % 1000L * 1000L),
73                  packet.readableBytes(),
74                  packet.readableBytes()
75          );
76  
77          if (pcapWriteHandler.sharedOutputStream()) {
78              synchronized (outputStream) {
79                  packetHeaderBuf.readBytes(outputStream, packetHeaderBuf.readableBytes());
80                  packet.readBytes(outputStream, packet.readableBytes());
81              }
82          } else {
83              packetHeaderBuf.readBytes(outputStream, packetHeaderBuf.readableBytes());
84              packet.readBytes(outputStream, packet.readableBytes());
85          }
86      }
87  
88      @Override
89      public String toString() {
90          return "PcapWriter{" +
91                  "outputStream=" + outputStream +
92                  '}';
93      }
94  
95      @Override
96      public void close() throws IOException {
97          if (pcapWriteHandler.state() == State.CLOSED) {
98              logger.debug("PcapWriter is already closed");
99          } else {
100             if (pcapWriteHandler.sharedOutputStream()) {
101                 synchronized (outputStream) {
102                     outputStream.flush();
103                 }
104             } else {
105                 outputStream.flush();
106                 outputStream.close();
107             }
108             pcapWriteHandler.markClosed();
109             logger.debug("PcapWriter is now closed");
110         }
111     }
112 }