DaapInputStream.java

/*
 * Digital Audio Access Protocol (DAAP) Library
 * Copyright (C) 2004-2010 Roger Kapsi
 *
 * 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 org.ardverk.daap;

import java.io.ByteArrayInputStream;
import java.io.EOFException;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;

import org.ardverk.daap.chunks.ByteChunk;
import org.ardverk.daap.chunks.Chunk;
import org.ardverk.daap.chunks.ChunkFactory;
import org.ardverk.daap.chunks.ContainerChunk;
import org.ardverk.daap.chunks.DateChunk;
import org.ardverk.daap.chunks.IntChunk;
import org.ardverk.daap.chunks.LongChunk;
import org.ardverk.daap.chunks.ShortChunk;
import org.ardverk.daap.chunks.StringChunk;
import org.ardverk.daap.chunks.VersionChunk;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class DaapInputStream extends FilterInputStream {

    private static final Logger LOG = LoggerFactory
            .getLogger(DaapInputStream.class);

    private ChunkFactory factory = null;

    public DaapInputStream(InputStream in) {
        super(in);
    }

    public int read() throws IOException {
        int b = super.read();
        if (b < 0) {
            throw new EOFException();
        }
        return b;
    }

    /*
     * Re: skip(length-Chunk.XYZ_LENGTH);
     * 
     * iTunes states in Content-Codes responses that Chunk X is of type Y and
     * has hence the length Z. A Byte has for example the length 1. But in some
     * cases iTunes uses a different length for Bytes! It's probably a bug in
     * iTunes...
     */

    public int read(int length) throws IOException {
        skip(length - Chunk.BYTE_LENGTH);
        return read();
    }

    public int readShort(int length) throws IOException {
        skip(length - Chunk.SHORT_LENGTH);
        return (read() << 8) | read();
    }

    public int readInt(int length) throws IOException {
        skip(length - Chunk.INT_LENGTH);
        return (read() << 24) | (read() << 16) | (read() << 8) | read();
    }

    public long readLong(int length) throws IOException {
        skip(length - Chunk.LONG_LENGTH);
        return (read() << 54l) | (read() << 48l) | (read() << 40l)
                | (read() << 32l) | (read() << 24l) | (read() << 16l)
                | (read() << 8l) | read();
    }

    public String readString(int length) throws IOException {
        if (length == 0) {
            return null;
        }

        byte[] b = new byte[length];
        read(b, 0, b.length);
        return new String(b, DaapUtil.UTF_8);
    }

    public int readContentCode() throws IOException {
        return readInt(Chunk.INT_LENGTH);
    }

    public int readLength() throws IOException {
        return readInt(Chunk.INT_LENGTH);
    }

    public Chunk readChunk() throws IOException {
        int contentCode = readContentCode();
        int length = readLength();

        if (factory == null) {
            factory = new ChunkFactory();
        }

        Chunk chunk = factory.newChunk(contentCode);

        if (length > 0) {
            if (chunk instanceof ByteChunk) {
                checkLength(chunk, Chunk.BYTE_LENGTH, length);
                ((ByteChunk) chunk).setValue(read(length));
            } else if (chunk instanceof ShortChunk) {
                checkLength(chunk, Chunk.SHORT_LENGTH, length);
                ((ShortChunk) chunk).setValue(readShort(length));
            } else if (chunk instanceof IntChunk) {
                checkLength(chunk, Chunk.INT_LENGTH, length);
                ((IntChunk) chunk).setValue(readInt(length));
            } else if (chunk instanceof LongChunk) {
                checkLength(chunk, Chunk.LONG_LENGTH, length);
                ((LongChunk) chunk).setValue(readLong(length));
            } else if (chunk instanceof StringChunk) {
                ((StringChunk) chunk).setValue(readString(length));
            } else if (chunk instanceof DateChunk) {
                checkLength(chunk, Chunk.DATE_LENGTH, length);
                ((DateChunk) chunk).setValue(readInt(length));
            } else if (chunk instanceof VersionChunk) {
                checkLength(chunk, Chunk.VERSION_LENGTH, length);
                ((VersionChunk) chunk).setValue(readInt(length));
            } else if (chunk instanceof ContainerChunk) {
                byte[] b = new byte[length];
                read(b, 0, b.length);
                DaapInputStream in = new DaapInputStream(
                        new ByteArrayInputStream(b));
                while (in.available() > 0) {
                    ((ContainerChunk) chunk).add(in.readChunk());
                }
                in.close();
            } else {
                throw new IOException("Unknown Chunk Type: " + chunk);
            }
        }

        return chunk;
    }

    /**
     * Throws an IOE if expected differs from length
     */
    private static void checkLength(Chunk chunk, int expected, int length) {
        if (expected != length) {
            // throw new IOException("Expected a chunk with length " + expected
            // + " but got " + length + " (" + chunk.getContentCodeString() +
            // ")");

            if (LOG.isWarnEnabled()) {
                LOG.warn("Expected a chunk with length " + expected
                        + " but got " + length + " ("
                        + chunk.getContentCodeString() + ")");
            }
        }
    }
}