Android Open Source - wototoplayer Name Value Block Reader

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License

The source code is released under:

Copyright (c) 2015, Chris Greenhalgh All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met...

Java Source Code

/*
 * Copyright (C) 2012 Square, Inc.//  w ww .j  a v  a 2 s  . c o m
 *
 * 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.squareup.okhttp.internal.spdy;

import com.squareup.okhttp.internal.Util;
import java.io.Closeable;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.zip.DataFormatException;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;

/**
 * Reads a SPDY/3 Name/Value header block. This class is made complicated by the
 * requirement that we're strict with which bytes we put in the compressed bytes
 * buffer. We need to put all compressed bytes into that buffer -- but no other
 * bytes.
 */
class NameValueBlockReader implements Closeable {
  private final DataInputStream nameValueBlockIn;
  private final FillableInflaterInputStream fillableInflaterInputStream;
  private int compressedLimit;

  NameValueBlockReader(final InputStream in) {
    // Limit the inflater input stream to only those bytes in the Name/Value block. We cut the
    // inflater off at its source because we can't predict the ratio of compressed bytes to
    // uncompressed bytes.
    InputStream throttleStream = new InputStream() {
      @Override public int read() throws IOException {
        return Util.readSingleByte(this);
      }

      @Override public int read(byte[] buffer, int offset, int byteCount) throws IOException {
        byteCount = Math.min(byteCount, compressedLimit);
        int consumed = in.read(buffer, offset, byteCount);
        compressedLimit -= consumed;
        return consumed;
      }

      @Override public void close() throws IOException {
        in.close();
      }
    };

    // Subclass inflater to install a dictionary when it's needed.
    Inflater inflater = new Inflater() {
      @Override public int inflate(byte[] buffer, int offset, int count)
          throws DataFormatException {
        int result = super.inflate(buffer, offset, count);
        if (result == 0 && needsDictionary()) {
          setDictionary(Spdy3.DICTIONARY);
          result = super.inflate(buffer, offset, count);
        }
        return result;
      }
    };

    fillableInflaterInputStream = new FillableInflaterInputStream(throttleStream, inflater);
    nameValueBlockIn = new DataInputStream(fillableInflaterInputStream);
  }

  /** Extend the inflater stream so we can eagerly fill the compressed bytes buffer if necessary. */
  static class FillableInflaterInputStream extends InflaterInputStream {
    public FillableInflaterInputStream(InputStream in, Inflater inf) {
      super(in, inf);
    }

    @Override public void fill() throws IOException {
      super.fill(); // This method is protected in the superclass.
    }
  }

  public List<String> readNameValueBlock(int length) throws IOException {
    this.compressedLimit += length;
    try {
      int numberOfPairs = nameValueBlockIn.readInt();
      if (numberOfPairs < 0) {
        throw new IOException("numberOfPairs < 0: " + numberOfPairs);
      }
      if (numberOfPairs > 1024) {
        throw new IOException("numberOfPairs > 1024: " + numberOfPairs);
      }
      List<String> entries = new ArrayList<String>(numberOfPairs * 2);
      for (int i = 0; i < numberOfPairs; i++) {
        String name = readString();
        String values = readString();
        if (name.length() == 0) throw new IOException("name.length == 0");
        entries.add(name);
        entries.add(values);
      }

      doneReading();

      return entries;
    } catch (DataFormatException e) {
      throw new IOException(e.getMessage());
    }
  }

  private void doneReading() throws IOException {
    if (compressedLimit == 0) return;

    // Read any outstanding unread bytes. One side-effect of deflate compression is that sometimes
    // there are bytes remaining in the stream after we've consumed all of the content.
    fillableInflaterInputStream.fill();

    if (compressedLimit != 0) {
      throw new IOException("compressedLimit > 0: " + compressedLimit);
    }
  }

  private String readString() throws DataFormatException, IOException {
    int length = nameValueBlockIn.readInt();
    byte[] bytes = new byte[length];
    Util.readFully(nameValueBlockIn, bytes);
    return new String(bytes, 0, length, "UTF-8");
  }

  @Override public void close() throws IOException {
    nameValueBlockIn.close();
  }
}

Java Source Code List

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