/* RecordInput.java -- record layer input.
   Copyright (C) 2003,2004  Casey Marshall <rsdio@metastatic.org>

This file is a part of Jessie.

Jessie is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.

Jessie 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
for more details.

You should have received a copy of the GNU General Public License along
with Jessie; if not, write to the

   Free Software Foundation, Inc.,
   59 Temple Place, Suite 330,
   Boston, MA  02111-1307
   USA

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under terms
of your choice, provided that you also meet, for each linked independent
module, the terms and conditions of the license of that module.  An
independent module is a module which is not derived from or based on
this library.  If you modify this library, you may extend this exception
to your version of the library, but you are not obligated to do so.  If
you do not wish to do so, delete this exception statement from your
version.  */


package org.metastatic.jessie.provider;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.InputStream;
import java.io.IOException;
import java.io.PrintWriter;

import javax.net.ssl.SSLProtocolException;

class RecordInput
{

  // Fields.
  // -------------------------------------------------------------------------

  private static final boolean DEBUG_RECORD_LAYER = false;
  private static final PrintWriter debug = new PrintWriter (System.err, true);

  private byte[] fragment;
  private int index;
  private ContentType type;

  private final DataInputStream in;
  private Session session;

  // Constructor.
  // -------------------------------------------------------------------------

  RecordInput (final InputStream in, final Session session)
  {
    this.in = new DataInputStream (in);
    this.session = session;
  }

  // Instance methods.
  // -------------------------------------------------------------------------

  synchronized int available (ContentType type) throws IOException
  {
    if (fragment == null)
      {
        readRecord ();
      }
    if (type != this.type)
      {
        return 0;
      }
    return fragment.length - index;
  }

  void setSession (Session session)
  {
    this.session = session;
  }

  synchronized int read (byte[] buf, int off, int len, ContentType type)
    throws IOException
  {
    if (off < 0 || len < 0 || off + len > buf.length)
      {
        throw new ArrayIndexOutOfBoundsException ("size=" + buf.length +
                                                  " off=" + off + " len=" + len);
      }
    if (fragment == null || index >= fragment.length)
      {
        readRecord ();
      }
    if (type != this.type)
      {
        return 0;
      }
    len = Math.min (len, fragment.length - index);
    System.arraycopy (fragment, index, buf, off, len);
    index += len;
    return len;
  }

  boolean pollClose () throws IOException
  {
    if (fragment == null || index >= fragment.length)
      {
        try
          {
            readRecord();
          }
        catch (AlertException ae)
          {
            Alert alert = ae.getAlert();
            if (alert.getDescription() == Alert.Description.CLOSE_NOTIFY)
              {
                return true;
              }
            throw ae;
          }
      }
    return false;
  }

  private void readRecord() throws IOException
  {
    type = ContentType.read (in);
    if ((type.getValue() & 0x80) != 0 || (type.getValue() & 0x40) != 0)
      {
        in.read();
        if ((type.getValue() & 0x40) != 0)
          {
            in.read();
          }
        type = ContentType.read(in);
        if (type != ContentType.CLIENT_HELLO_V2)
          {
            throw new SSLProtocolException("unsupported V2 message");
          }
        type = ContentType.HANDSHAKE;
        // Record this message, and re-present it as a normal handshake
        // layer message. ClientHello will handle the real parsing.
        ByteArrayOutputStream buffer = new ByteArrayOutputStream (256);
        buffer.write(1); // The type we just read.
        RecordingInputStream in2 = new RecordingInputStream (in, buffer);
        ProtocolVersion version = ProtocolVersion.read (in2);
        if (version.compareTo (ProtocolVersion.SSL_3) < 0)
          {
            throw new SSLProtocolException("unsupported client version");
          }
        int len = (in2.read() & 0xFF) << 8 | (in2.read() & 0xFF);
        len += (in2.read() & 0xFF) << 8 | (in2.read() & 0xFF);
        len += (in2.read() & 0xFF) << 8 | (in2.read() & 0xFF);
        int count = 0;
        while (count < len)
          {
            int l = (int) in2.skip(len - count);
            if (l > 0)
              {
                count += l;
              }
          }
        fragment = buffer.toByteArray ();
        index = 0;

        // We can't be encrypted/MACed/compressed here, since a V2 message
        // will only be sent as the first message, and only by the client.
        return;
      }
    ProtocolVersion v = ProtocolVersion.read (in);
    int len = in.readUnsignedShort ();
    if (len > session.params.getFragmentLength() + 2048)
      {
        throw new OverflowException();
      }
    fragment = new byte [len];
    in.readFully (fragment);

    if (DEBUG_RECORD_LAYER)
      {
        debug.println (">> READ RECORD <<");
        debug.println ("struct {");
        debug.println ("  type = " + type + ";");
        debug.println ("  version = " + v + ";");
        debug.println ("  length = " + len + ";");
        debug.print (Util.hexDump (fragment, "  "));
        debug.println ("} TLSCiphertext;");
      }

    fragment = session.params.decrypt (fragment, v, type);
    index = 0;

    CSPRNG.SYSTEM_RANDOM.addRandomBytes (fragment, 0, fragment.length);

    if (type == ContentType.ALERT)
      {
        Alert alert = Alert.read (new ByteArrayInputStream (fragment));
        session.currentAlert = alert;
      }
    if (session.currentAlert != null)
      {
        throw new AlertException (session.currentAlert, false);
      }
  }
}