/*
 * Copyright (c) 1999, 2006, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package sun.net.www.http;

import java.io.*;
import java.util.*;

import sun.net.*;
import sun.net.www.*;

A ChunkedInputStream provides a stream for reading a body of
a http message that can be sent as a series of chunks, each with its own
size indicator. Optionally the last chunk can be followed by trailers
containing entity-header fields.

A ChunkedInputStream is also Hurryable so it
can be hurried to the end of the stream if the bytes are available on
the underlying stream.
/**
 * A <code>ChunkedInputStream</code> provides a stream for reading a body of
 * a http message that can be sent as a series of chunks, each with its own
 * size indicator. Optionally the last chunk can be followed by trailers
 * containing entity-header fields.
 * <p>
 * A <code>ChunkedInputStream</code> is also <code>Hurryable</code> so it
 * can be hurried to the end of the stream if the bytes are available on
 * the underlying stream.
 */
public
class ChunkedInputStream extends InputStream implements Hurryable {

    
The underlying stream
/**
     * The underlying stream
     */
    private InputStream in;

    
The HttpClient that should be notified when the chunked stream has
completed.
/**
     * The <code>HttpClient</code> that should be notified when the chunked stream has
     * completed.
     */
    private HttpClient hc;

    
The MessageHeader that is populated with any optional trailer
that appear after the last chunk.
/**
     * The <code>MessageHeader</code> that is populated with any optional trailer
     * that appear after the last chunk.
     */
    private MessageHeader responses;

    
The size, in bytes, of the chunk that is currently being read.
This size is only valid if the current position in the underlying
input stream is inside a chunk (ie: state == STATE_READING_CHUNK).
/**
     * The size, in bytes, of the chunk that is currently being read.
     * This size is only valid if the current position in the underlying
     * input stream is inside a chunk (ie: state == STATE_READING_CHUNK).
     */
    private int chunkSize;

    
The number of bytes read from the underlying stream for the current
chunk. This value is always in the range 0 through to
chunkSize
/**
     * The number of bytes read from the underlying stream for the current
     * chunk. This value is always in the range <code>0</code> through to
     * <code>chunkSize</code>
     */
    private int chunkRead;

    
The internal buffer array where chunk data is available for the
application to read.
/**
     * The internal buffer array where chunk data is available for the
     * application to read.
     */
    private byte chunkData[] = new byte[4096];

    
The current position in the buffer. It contains the index
of the next byte to read from chunkData
/**
     * The current position in the buffer. It contains the index
     * of the next byte to read from <code>chunkData</code>
     */
    private int chunkPos;

    
The index one greater than the index of the last valid byte in the
buffer. This value is always in the range 0 through
chunkData.length.
/**
     * The index one greater than the index of the last valid byte in the
     * buffer. This value is always in the range <code>0</code> through
     * <code>chunkData.length</code>.
     */
    private int chunkCount;

    
The internal buffer where bytes from the underlying stream can be
read. It may contain bytes representing chunk-size, chunk-data, or
trailer fields.
/**
     * The internal buffer where bytes from the underlying stream can be
     * read. It may contain bytes representing chunk-size, chunk-data, or
     * trailer fields.
     */
    private byte rawData[] = new byte[32];

    
The current position in the buffer. It contains the index
of the next byte to read from rawData
/**
     * The current position in the buffer. It contains the index
     * of the next byte to read from <code>rawData</code>
     */
    private int rawPos;

    
The index one greater than the index of the last valid byte in the
buffer. This value is always in the range 0 through
rawData.length.
/**
     * The index one greater than the index of the last valid byte in the
     * buffer. This value is always in the range <code>0</code> through
     * <code>rawData.length</code>.
     */
    private int rawCount;

    
Indicates if an error was encountered when processing the chunked
stream.
/**
     * Indicates if an error was encountered when processing the chunked
     * stream.
     */
    private boolean error;

    
Indicates if the chunked stream has been closed using the
close method.
/**
     * Indicates if the chunked stream has been closed using the
     * <code>close</code> method.
     */
    private boolean closed;

    /*
     * Maximum chunk header size of 2KB + 2 bytes for CRLF
     */
    private final static int MAX_CHUNK_HEADER_SIZE = 2050;

    
State to indicate that next field should be :-
 chunk-size [ chunk-extension ] CRLF
/**
     * State to indicate that next field should be :-
     *  chunk-size [ chunk-extension ] CRLF
     */
    static final int STATE_AWAITING_CHUNK_HEADER    = 1;

    
State to indicate that we are currently reading the chunk-data.
/**
     * State to indicate that we are currently reading the chunk-data.
     */
    static final int STATE_READING_CHUNK            = 2;

    
Indicates that a chunk has been completely read and the next
fields to be examine should be CRLF
/**
     * Indicates that a chunk has been completely read and the next
     * fields to be examine should be CRLF
     */
    static final int STATE_AWAITING_CHUNK_EOL       = 3;

    
Indicates that all chunks have been read and the next field
should be optional trailers or an indication that the chunked
stream is complete.
/**
     * Indicates that all chunks have been read and the next field
     * should be optional trailers or an indication that the chunked
     * stream is complete.
     */
    static final int STATE_AWAITING_TRAILERS        = 4;

    
State to indicate that the chunked stream is complete and
no further bytes should be read from the underlying stream.
/**
     * State to indicate that the chunked stream is complete and
     * no further bytes should be read from the underlying stream.
     */
    static final int STATE_DONE                     = 5;

    
Indicates the current state.
/**
     * Indicates the current state.
     */
    private int state;


    
Check to make sure that this stream has not been closed.
/**
     * Check to make sure that this stream has not been closed.
     */
    private void ensureOpen() throws IOException {
        if (closed) {
            throw new IOException("stream is closed");
        }
    }


    
Ensures there is size bytes available in
rawData. This requires that we either
shift the bytes in use to the begining of the buffer
or allocate a large buffer with sufficient space available.
/**
     * Ensures there is <code>size</code> bytes available in
     * <code>rawData</code>. This requires that we either
     * shift the bytes in use to the begining of the buffer
     * or allocate a large buffer with sufficient space available.
     */
    private void ensureRawAvailable(int size) {
        if (rawCount + size > rawData.length) {
            int used = rawCount - rawPos;
            if (used + size > rawData.length) {
                byte tmp[] = new byte[used + size];
                if (used > 0) {
                    System.arraycopy(rawData, rawPos, tmp, 0, used);
                }
                rawData = tmp;
            } else {
                if (used > 0) {
                    System.arraycopy(rawData, rawPos, rawData, 0, used);
                }
            }
            rawCount = used;
            rawPos = 0;
        }
    }


    
Close the underlying input stream by either returning it to the
keep alive cache or closing the stream.

As a chunked stream is inheritly persistent (see HTTP 1.1 RFC) the
underlying stream can be returned to the keep alive cache if the
stream can be completely read without error.
/**
     * Close the underlying input stream by either returning it to the
     * keep alive cache or closing the stream.
     * <p>
     * As a chunked stream is inheritly persistent (see HTTP 1.1 RFC) the
     * underlying stream can be returned to the keep alive cache if the
     * stream can be completely read without error.
     */
    private void closeUnderlying() throws IOException {
        if (in == null) {
            return;
        }

        if (!error && state == STATE_DONE) {
            hc.finished();
        } else {
            if (!hurry()) {
                hc.closeServer();
            }
        }

        in = null;
    }

    
Attempt to read the remainder of a chunk directly into the
caller's buffer.

Return the number of bytes read.
/**
     * Attempt to read the remainder of a chunk directly into the
     * caller's buffer.
     * <p>
     * Return the number of bytes read.
     */
    private int fastRead(byte[] b, int off, int len) throws IOException {

        // assert state == STATE_READING_CHUNKS;

        int remaining = chunkSize - chunkRead;
        int cnt = (remaining < len) ? remaining : len;
        if (cnt > 0) {
            int nread;
            try {
                nread = in.read(b, off, cnt);
            } catch (IOException e) {
                error = true;
                throw e;
            }
            if (nread > 0) {
                chunkRead += nread;
                if (chunkRead >= chunkSize) {
                    state = STATE_AWAITING_CHUNK_EOL;
                }
                return nread;
            }
            error = true;
            throw new IOException("Premature EOF");
        } else {
            return 0;
        }
    }

    
Process any outstanding bytes that have already been read into
rawData.

The parsing of the chunked stream is performed as a state machine with
state representing the current state of the processing.

Returns when either all the outstanding bytes in rawData have been
processed or there is insufficient bytes available to continue
processing. When the latter occurs rawPos will not have
been updated and thus the processing can be restarted once further
bytes have been read into rawData.
/**
     * Process any outstanding bytes that have already been read into
     * <code>rawData</code>.
     * <p>
     * The parsing of the chunked stream is performed as a state machine with
     * <code>state</code> representing the current state of the processing.
     * <p>
     * Returns when either all the outstanding bytes in rawData have been
     * processed or there is insufficient bytes available to continue
     * processing. When the latter occurs <code>rawPos</code> will not have
     * been updated and thus the processing can be restarted once further
     * bytes have been read into <code>rawData</code>.
     */
    private void processRaw() throws IOException {
        int pos;
        int i;

        while (state != STATE_DONE) {

            switch (state) {

                /**
                 * We are awaiting a line with a chunk header
                 */
                case STATE_AWAITING_CHUNK_HEADER:
                    /*
                     * Find \n to indicate end of chunk header. If not found when there is
                     * insufficient bytes in the raw buffer to parse a chunk header.
                     */
                    pos = rawPos;
                    while (pos < rawCount) {
                        if (rawData[pos] == '\n') {
                            break;
                        }
                        pos++;
                        if ((pos - rawPos) >= MAX_CHUNK_HEADER_SIZE) {
                            error = true;
                            throw new IOException("Chunk header too long");
                        }
                    }
                    if (pos >= rawCount) {
                        return;
                    }

                    /*
                     * Extract the chunk size from the header (ignoring extensions).
                     */
                    String header = new String(rawData, rawPos, pos-rawPos+1, "US-ASCII");
                    for (i=0; i < header.length(); i++) {
                        if (Character.digit(header.charAt(i), 16) == -1)
                            break;
                    }
                    try {
                        chunkSize = Integer.parseInt(header.substring(0, i), 16);
                    } catch (NumberFormatException e) {
                        error = true;
                        throw new IOException("Bogus chunk size");
                    }

                    /*
                     * Chunk has been parsed so move rawPos to first byte of chunk
                     * data.
                     */
                    rawPos = pos + 1;
                    chunkRead = 0;

                    /*
                     * A chunk size of 0 means EOF.
                     */
                    if (chunkSize > 0) {
                        state = STATE_READING_CHUNK;
                    } else {
                        state = STATE_AWAITING_TRAILERS;
                    }
                    break;


                /**
                 * We are awaiting raw entity data (some may have already been
                 * read). chunkSize is the size of the chunk; chunkRead is the
                 * total read from the underlying stream to date.
                 */
                case STATE_READING_CHUNK :
                    /* no data available yet */
                    if (rawPos >= rawCount) {
                        return;
                    }

                    /*
                     * Compute the number of bytes of chunk data available in the
                     * raw buffer.
                     */
                    int copyLen = Math.min( chunkSize-chunkRead, rawCount-rawPos );

                    /*
                     * Expand or compact chunkData if needed.
                     */
                    if (chunkData.length < chunkCount + copyLen) {
                        int cnt = chunkCount - chunkPos;
                        if (chunkData.length < cnt + copyLen) {
                            byte tmp[] = new byte[cnt + copyLen];
                            System.arraycopy(chunkData, chunkPos, tmp, 0, cnt);
                            chunkData = tmp;
                        } else {
                            System.arraycopy(chunkData, chunkPos, chunkData, 0, cnt);
                        }
                        chunkPos = 0;
                        chunkCount = cnt;
                    }

                    /*
                     * Copy the chunk data into chunkData so that it's available
                     * to the read methods.
                     */
                    System.arraycopy(rawData, rawPos, chunkData, chunkCount, copyLen);
                    rawPos += copyLen;
                    chunkCount += copyLen;
                    chunkRead += copyLen;

                    /*
                     * If all the chunk has been copied into chunkData then the next
                     * token should be CRLF.
                     */
                    if (chunkSize - chunkRead <= 0) {
                        state = STATE_AWAITING_CHUNK_EOL;
                    } else {
                        return;
                    }
                    break;


                /**
                 * Awaiting CRLF after the chunk
                 */
                case STATE_AWAITING_CHUNK_EOL:
                    /* not available yet */
                    if (rawPos + 1 >= rawCount) {
                        return;
                    }

                    if (rawData[rawPos] != '\r') {
                        error = true;
                        throw new IOException("missing CR");
                    }
                    if (rawData[rawPos+1] != '\n') {
                        error = true;
                        throw new IOException("missing LF");
                    }
                    rawPos += 2;

                    /*
                     * Move onto the next chunk
                     */
                    state = STATE_AWAITING_CHUNK_HEADER;
                    break;


                /**
                 * Last chunk has been read so not we're waiting for optional
                 * trailers.
                 */
                case STATE_AWAITING_TRAILERS:

                    /*
                     * Do we have an entire line in the raw buffer?
                     */
                    pos = rawPos;
                    while (pos < rawCount) {
                        if (rawData[pos] == '\n') {
                            break;
                        }
                        pos++;
                    }
                    if (pos >= rawCount) {
                        return;
                    }

                    if (pos == rawPos) {
                        error = true;
                        throw new IOException("LF should be proceeded by CR");
                    }
                    if (rawData[pos-1] != '\r') {
                        error = true;
                        throw new IOException("LF should be proceeded by CR");
                    }

                    /*
                     * Stream done so close underlying stream.
                     */
                    if (pos == (rawPos + 1)) {

                        state = STATE_DONE;
                        closeUnderlying();

                        return;
                    }

                    /*
                     * Extract any tailers and append them to the message
                     * headers.
                     */
                    String trailer = new String(rawData, rawPos, pos-rawPos, "US-ASCII");
                    i = trailer.indexOf(':');
                    if (i == -1) {
                        throw new IOException("Malformed tailer - format should be key:value");
                    }
                    String key = (trailer.substring(0, i)).trim();
                    String value = (trailer.substring(i+1, trailer.length())).trim();

                    responses.add(key, value);

                    /*
                     * Move onto the next trailer.
                     */
                    rawPos = pos+1;
                    break;

            } /* switch */
        }
    }


    
Reads any available bytes from the underlying stream into
rawData and returns the number of bytes of
chunk data available in chunkData that the
application can read.
/**
     * Reads any available bytes from the underlying stream into
     * <code>rawData</code> and returns the number of bytes of
     * chunk data available in <code>chunkData</code> that the
     * application can read.
     */
    private int readAheadNonBlocking() throws IOException {

        /*
         * If there's anything available on the underlying stream then we read
         * it into the raw buffer and process it. Processing ensures that any
         * available chunk data is made available in chunkData.
         */
        int avail = in.available();
        if (avail > 0) {

            /* ensure that there is space in rawData to read the available */
            ensureRawAvailable(avail);

            int nread;
            try {
                nread = in.read(rawData, rawCount, avail);
            } catch (IOException e) {
                error = true;
                throw e;
            }
            if (nread < 0) {
                error = true;   /* premature EOF ? */
                return -1;
            }
            rawCount += nread;

            /*
             * Process the raw bytes that have been read.
             */
            processRaw();
        }

        /*
         * Return the number of chunked bytes available to read
         */
        return chunkCount - chunkPos;
    }

    
Reads from the underlying stream until there is chunk data
available in chunkData for the application to
read.
/**
     * Reads from the underlying stream until there is chunk data
     * available in <code>chunkData</code> for the application to
     * read.
     */
    private int readAheadBlocking() throws IOException {

        do {
            /*
             * All of chunked response has been read to return EOF.
             */
            if (state == STATE_DONE) {
                return -1;
            }

            /*
             * We must read into the raw buffer so make sure there is space
             * available. We use a size of 32 to avoid too much chunk data
             * being read into the raw buffer.
             */
            ensureRawAvailable(32);
            int nread;
            try {
                nread = in.read(rawData, rawCount, rawData.length-rawCount);
            } catch (IOException e) {
                error = true;
                throw e;
            }

            /**
             * If we hit EOF it means there's a problem as we should never
             * attempt to read once the last chunk and trailers have been
             * received.
             */
            if (nread < 0) {
                error = true;
                throw new IOException("Premature EOF");
            }

            /**
             * Process the bytes from the underlying stream
             */
            rawCount += nread;
            processRaw();

        } while (chunkCount <= 0);

        /*
         * Return the number of chunked bytes available to read
         */
        return chunkCount - chunkPos;
    }

    
Read ahead in either blocking or non-blocking mode. This method
is typically used when we run out of available bytes in
chunkData or we need to determine how many bytes
are available on the input stream.
/**
     * Read ahead in either blocking or non-blocking mode. This method
     * is typically used when we run out of available bytes in
     * <code>chunkData</code> or we need to determine how many bytes
     * are available on the input stream.
     */
    private int readAhead(boolean allowBlocking) throws IOException {

        /*
         * Last chunk already received - return EOF
         */
        if (state == STATE_DONE) {
            return -1;
        }

        /*
         * Reset position/count if data in chunkData is exhausted.
         */
        if (chunkPos >= chunkCount) {
            chunkCount = 0;
            chunkPos = 0;
        }

        /*
         * Read ahead blocking or non-blocking
         */
        if (allowBlocking) {
            return readAheadBlocking();
        } else {
            return readAheadNonBlocking();
        }
    }

    
Creates a ChunkedInputStream and saves its  arguments, for
later use.
Params:
in –   the underlying input stream.
hc –   the HttpClient
responses –   the MessageHeader that should be populated with optional
                     trailers./**
     * Creates a <code>ChunkedInputStream</code> and saves its  arguments, for
     * later use.
     *
     * @param   in   the underlying input stream.
     * @param   hc   the HttpClient
     * @param   responses   the MessageHeader that should be populated with optional
     *                      trailers.
     */
    public ChunkedInputStream(InputStream in, HttpClient hc, MessageHeader responses) throws IOException {

        /* save arguments */
        this.in = in;
        this.responses = responses;
        this.hc = hc;

        /*
         * Set our initial state to indicate that we are first starting to
         * look for a chunk header.
         */
        state = STATE_AWAITING_CHUNK_HEADER;
    }

    
See
the general contract of the read
method of InputStream.
Throws:
IOException –  if an I/O error occurs.
See Also:
FilterInputStream.in
Returns:
    the next byte of data, or -1 if the end of the
            stream is reached./**
     * See
     * the general contract of the <code>read</code>
     * method of <code>InputStream</code>.
     *
     * @return     the next byte of data, or <code>-1</code> if the end of the
     *             stream is reached.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterInputStream#in
     */
    public synchronized int read() throws IOException {
        ensureOpen();
        if (chunkPos >= chunkCount) {
            if (readAhead(true) <= 0) {
                return -1;
            }
        }
        return chunkData[chunkPos++] & 0xff;
    }


    
Reads bytes from this stream into the specified byte array, starting at
the given offset.
Params:
b –     destination buffer.
off –   offset at which to start storing bytes.
len –   maximum number of bytes to read.
Throws:
IOException –  if an I/O error occurs.
Returns:
    the number of bytes read, or -1 if the end of
            the stream has been reached./**
     * Reads bytes from this stream into the specified byte array, starting at
     * the given offset.
     *
     * @param      b     destination buffer.
     * @param      off   offset at which to start storing bytes.
     * @param      len   maximum number of bytes to read.
     * @return     the number of bytes read, or <code>-1</code> if the end of
     *             the stream has been reached.
     * @exception  IOException  if an I/O error occurs.
     */
    public synchronized int read(byte b[], int off, int len)
        throws IOException
    {
        ensureOpen();
        if ((off < 0) || (off > b.length) || (len < 0) ||
            ((off + len) > b.length) || ((off + len) < 0)) {
            throw new IndexOutOfBoundsException();
        } else if (len == 0) {
            return 0;
        }

        int avail = chunkCount - chunkPos;
        if (avail <= 0) {
            /*
             * Optimization: if we're in the middle of the chunk read
             * directly from the underlying stream into the caller's
             * buffer
             */
            if (state == STATE_READING_CHUNK) {
                return fastRead( b, off, len );
            }

            /*
             * We're not in the middle of a chunk so we must read ahead
             * until there is some chunk data available.
             */
            avail = readAhead(true);
            if (avail < 0) {
                return -1;      /* EOF */
            }
        }
        int cnt = (avail < len) ? avail : len;
        System.arraycopy(chunkData, chunkPos, b, off, cnt);
        chunkPos += cnt;

        return cnt;
    }

    
Returns the number of bytes that can be read from this input
stream without blocking.
Throws:
IOException –  if an I/O error occurs.
See Also:
FilterInputStream.in
Returns:
    the number of bytes that can be read from this input
            stream without blocking./**
     * Returns the number of bytes that can be read from this input
     * stream without blocking.
     *
     * @return     the number of bytes that can be read from this input
     *             stream without blocking.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterInputStream#in
     */
    public synchronized int available() throws IOException {
        ensureOpen();

        int avail = chunkCount - chunkPos;
        if(avail > 0) {
            return avail;
        }

        avail = readAhead(false);

        if (avail < 0) {
            return 0;
        } else  {
            return avail;
        }
    }

    
Close the stream by either returning the connection to the
keep alive cache or closing the underlying stream.

If the chunked response hasn't been completely read we
try to "hurry" to the end of the response. If this is
possible (without blocking) then the connection can be
returned to the keep alive cache.
Throws:
IOException –  if an I/O error occurs./**
     * Close the stream by either returning the connection to the
     * keep alive cache or closing the underlying stream.
     * <p>
     * If the chunked response hasn't been completely read we
     * try to "hurry" to the end of the response. If this is
     * possible (without blocking) then the connection can be
     * returned to the keep alive cache.
     *
     * @exception  IOException  if an I/O error occurs.
     */
    public synchronized void close() throws IOException {
        if (closed) {
            return;
        }
        closeUnderlying();
        closed = true;
    }

    
Hurry the input stream by reading everything from the underlying
stream. If the last chunk (and optional trailers) can be read without
blocking then the stream is considered hurried.

Note that if an error has occurred or we can't get to last chunk
without blocking then this stream can't be hurried and should be
closed.
/**
     * Hurry the input stream by reading everything from the underlying
     * stream. If the last chunk (and optional trailers) can be read without
     * blocking then the stream is considered hurried.
     * <p>
     * Note that if an error has occurred or we can't get to last chunk
     * without blocking then this stream can't be hurried and should be
     * closed.
     */
    public synchronized boolean hurry() {
        if (in == null || error) {
            return false;
        }

        try {
            readAhead(false);
        } catch (Exception e) {
            return false;
        }

        if (error) {
            return false;
        }

        return (state == STATE_DONE);
    }

}