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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  
28  package org.apache.http.impl.nio.codecs;
29  
30  import java.io.IOException;
31  import java.nio.ByteBuffer;
32  import java.nio.channels.FileChannel;
33  import java.nio.channels.ReadableByteChannel;
34  
35  import org.apache.http.ConnectionClosedException;
36  import org.apache.http.impl.io.HttpTransportMetricsImpl;
37  import org.apache.http.nio.FileContentDecoder;
38  import org.apache.http.nio.reactor.SessionInputBuffer;
39  import org.apache.http.util.Args;
40  
41  /**
42   * Content decoder that cuts off after a defined number of bytes. This class
43   * is used to receive content of HTTP messages where the end of the content
44   * entity is determined by the value of the {@code Content-Length header}.
45   * Entities transferred using this stream can be maximum {@link Long#MAX_VALUE}
46   * long.
47   * <p>
48   * This decoder is optimized to transfer data directly from the underlying
49   * I/O session's channel to a {@link FileChannel}, whenever
50   * possible avoiding intermediate buffering in the session buffer.
51   *
52   * @since 4.0
53   */
54  public class LengthDelimitedDecoder extends AbstractContentDecoder
55          implements FileContentDecoder {
56  
57      private final long contentLength;
58  
59      private long len;
60  
61      public LengthDelimitedDecoder(
62              final ReadableByteChannel channel,
63              final SessionInputBuffer buffer,
64              final HttpTransportMetricsImpl metrics,
65              final long contentLength) {
66          super(channel, buffer, metrics);
67          Args.notNegative(contentLength, "Content length");
68          this.contentLength = contentLength;
69      }
70  
71      @Override
72      public int read(final ByteBuffer dst) throws IOException {
73          Args.notNull(dst, "Byte buffer");
74          if (this.completed) {
75              return -1;
76          }
77          final int chunk = (int) Math.min((this.contentLength - this.len), Integer.MAX_VALUE);
78  
79          final int bytesRead;
80          if (this.buffer.hasData()) {
81              final int maxLen = Math.min(chunk, this.buffer.length());
82              bytesRead = this.buffer.read(dst, maxLen);
83          } else {
84              bytesRead = readFromChannel(dst, chunk);
85          }
86          if (bytesRead == -1) {
87              this.completed = true;
88              if (this.len < this.contentLength) {
89                  throw new ConnectionClosedException(
90                          "Premature end of Content-Length delimited message body (expected: "
91                          + this.contentLength + "; received: " + this.len);
92              }
93          }
94          this.len += bytesRead;
95          if (this.len >= this.contentLength) {
96              this.completed = true;
97          }
98          if (this.completed && bytesRead == 0) {
99              return -1;
100         } else {
101             return bytesRead;
102         }
103     }
104 
105     @Override
106     public long transfer(
107             final FileChannel dst,
108             final long position,
109             final long count) throws IOException {
110 
111         if (dst == null) {
112             return 0;
113         }
114         if (this.completed) {
115             return -1;
116         }
117 
118         final int chunk = (int) Math.min((this.contentLength - this.len), Integer.MAX_VALUE);
119 
120         final long bytesRead;
121         if (this.buffer.hasData()) {
122             final int maxLen = Math.min(chunk, this.buffer.length());
123             dst.position(position);
124             bytesRead = this.buffer.read(dst, maxLen);
125         } else {
126             if (this.channel.isOpen()) {
127                 if (position > dst.size()) {
128                     throw new IOException("Position past end of file [" + position +
129                             " > " + dst.size() + "]");
130                 }
131                 bytesRead = dst.transferFrom(this.channel, position, count < chunk ? count : chunk);
132             } else {
133                 bytesRead = -1;
134             }
135             if (bytesRead > 0) {
136                 this.metrics.incrementBytesTransferred(bytesRead);
137             }
138         }
139         if (bytesRead == -1) {
140             this.completed = true;
141             if (this.len < this.contentLength) {
142                 throw new ConnectionClosedException(
143                         "Premature end of Content-Length delimited message body (expected: "
144                         + this.contentLength + "; received: " + this.len);
145             }
146         }
147         this.len += bytesRead;
148         if (this.len >= this.contentLength) {
149             this.completed = true;
150         }
151         return bytesRead;
152     }
153 
154     @Override
155     public String toString() {
156         final StringBuilder sb = new StringBuilder();
157         sb.append("[content length: ");
158         sb.append(this.contentLength);
159         sb.append("; pos: ");
160         sb.append(this.len);
161         sb.append("; completed: ");
162         sb.append(this.completed);
163         sb.append("]");
164         return sb.toString();
165     }
166 }