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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 *
 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package com.sun.jndi.ldap.sasl;

import javax.security.sasl.Sasl;
import javax.security.sasl.SaslClient;
import javax.security.sasl.SaslException;
import java.io.IOException;
import java.io.EOFException;
import java.io.InputStream;

This class is used by clients of Java SASL that need to create an input stream
that uses SaslClient's unwrap() method to decode the SASL buffers
sent by the SASL server.
Extend from InputStream instead of FilterInputStream because
we need to override less methods in InputStream. That is, the
behavior of the default implementations in InputStream matches
more closely with the behavior we want in SaslInputStream.
Author:
Rosanna Lee/**
 * This class is used by clients of Java SASL that need to create an input stream
 * that uses SaslClient's unwrap() method to decode the SASL buffers
 * sent by the SASL server.
 *
 * Extend from InputStream instead of FilterInputStream because
 * we need to override less methods in InputStream. That is, the
 * behavior of the default implementations in InputStream matches
 * more closely with the behavior we want in SaslInputStream.
 *
 * @author Rosanna Lee
 */
public class SaslInputStream extends InputStream {
    private static final boolean debug = false;

    private byte[] saslBuffer;  // buffer for storing raw bytes
    private byte[] lenBuf = new byte[4];  // buffer for storing length

    private byte[] buf = new byte[0];   // buffer for storing processed bytes
                                        // Initialized to empty buffer
    private int bufPos = 0;             // read position in buf
    private InputStream in;             // underlying input stream
    private SaslClient sc;
    private int recvMaxBufSize = 65536;

    SaslInputStream(SaslClient sc, InputStream in) throws SaslException {
        super();
        this.in = in;
        this.sc = sc;

        String str = (String) sc.getNegotiatedProperty(Sasl.MAX_BUFFER);
        if (str != null) {
            try {
                recvMaxBufSize = Integer.parseInt(str);
            } catch (NumberFormatException e) {
                throw new SaslException(Sasl.MAX_BUFFER +
                    " property must be numeric string: " + str);
            }
        }
        saslBuffer = new byte[recvMaxBufSize];
    }

    public int read() throws IOException {
        byte[] inBuf = new byte[1];
        int count = read(inBuf, 0, 1);
        if (count > 0) {
            return inBuf[0];
        } else {
            return -1;
        }
    }

    public int read(byte[] inBuf, int start, int count) throws IOException {

        if (bufPos >= buf.length) {
            int actual = fill();   // read and unwrap next SASL buffer
            while (actual == 0) {  // ignore zero length content
                actual = fill();
            }
            if (actual == -1) {
                return -1;    // EOF
            }
        }

        int avail = buf.length - bufPos;
        if (count > avail) {
            // Requesting more that we have stored
            // Return all that we have; next invocation of read() will
            // trigger fill()
            System.arraycopy(buf, bufPos, inBuf, start, avail);
            bufPos = buf.length;
            return avail;
        } else {
            // Requesting less than we have stored
            // Return all that was requested
            System.arraycopy(buf, bufPos, inBuf, start, count);
            bufPos += count;
            return count;
        }
    }

    
Fills the buf with more data by reading a SASL buffer, unwrapping it,
and leaving the bytes in buf for read() to return.
Returns:
The number of unwrapped bytes available/**
     * Fills the buf with more data by reading a SASL buffer, unwrapping it,
     * and leaving the bytes in buf for read() to return.
     * @return The number of unwrapped bytes available
     */
    private int fill() throws IOException {
        // Read in length of buffer
        int actual = readFully(lenBuf, 4);
        if (actual != 4) {
            return -1;
        }
        int len = networkByteOrderToInt(lenBuf, 0, 4);

        if (len > recvMaxBufSize) {
            throw new IOException(
                len + "exceeds the negotiated receive buffer size limit:" +
                recvMaxBufSize);
        }

        if (debug) {
            System.err.println("reading " + len + " bytes from network");
        }

        // Read SASL buffer
        actual = readFully(saslBuffer, len);
        if (actual != len) {
            throw new EOFException("Expecting to read " + len +
                " bytes but got " + actual + " bytes before EOF");
        }

        // Unwrap
        buf = sc.unwrap(saslBuffer, 0, len);

        bufPos = 0;

        return buf.length;
    }

    
Read requested number of bytes before returning.
Returns:
The number of bytes actually read; -1 if none read/**
     * Read requested number of bytes before returning.
     * @return The number of bytes actually read; -1 if none read
     */
    private int readFully(byte[] inBuf, int total) throws IOException {
        int count, pos = 0;

        if (debug) {
            System.err.println("readFully " + total + " from " + in);
        }

        while (total > 0) {
            count = in.read(inBuf, pos, total);

            if (debug) {
                System.err.println("readFully read " + count);
            }

            if (count == -1 ) {
                return (pos == 0? -1 : pos);
            }
            pos += count;
            total -= count;
        }
        return pos;
    }

    public int available() throws IOException {
        return buf.length - bufPos;
    }

    public void close() throws IOException {
        SaslException save = null;
        try {
            sc.dispose(); // Dispose of SaslClient's state
        } catch (SaslException e) {
            // Save exception for throwing after closing 'in'
            save = e;
        }

        in.close();  // Close underlying input stream

        if (save != null) {
            throw save;
        }
    }

    
Returns the integer represented by  4 bytes in network byte order.
/**
     * Returns the integer represented by  4 bytes in network byte order.
     */
    // Copied from com.sun.security.sasl.util.SaslImpl.
    private static int networkByteOrderToInt(byte[] buf, int start, int count) {
        if (count > 4) {
            throw new IllegalArgumentException("Cannot handle more than 4 bytes");
        }

        int answer = 0;

        for (int i = 0; i < count; i++) {
            answer <<= 8;
            answer |= ((int)buf[start+i] & 0xff);
        }
        return answer;
    }
}