/* Extension.java -- A TLS hello extension.
   Copyright (C) 2003  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.EOFException;
import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.StringWriter;

final class Extension implements Constructed
{

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

  private final Type type;
  private final byte[] value;

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

  Extension(Type type, byte[] value)
  {
    if (type == null || value == null)
      {
        throw new NullPointerException();
      }
    this.type = type;
    this.value = value;
  }

  // Class method.
  // -------------------------------------------------------------------------

  static Extension read(InputStream in) throws IOException
  {
    Type t = Type.read(in);
    int len = (in.read() & 0xFF) << 8 | (in.read() & 0xFF);
    byte[] v = new byte[len];
    int count = 0;
    while (count < len)
      {
        int l = in.read(v, count, len - count);
        if (l == -1)
          {
            throw new EOFException("unexpected end of extension");
          }
        count += l;
      }
    return new Extension(t, v);
  }

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

  public void write(OutputStream out) throws IOException
  {
    out.write(type.getEncoded());
    out.write(value.length >>> 8 & 0xFF);
    out.write(value.length & 0xFF);
    out.write(value);
  }

  Type getType()
  {
    return type;
  }

  byte[] getValue()
  {
    return value;
  }

  public String toString()
  {
    StringWriter str = new StringWriter();
    PrintWriter out = new PrintWriter(str);
    out.println("struct {");
    out.println("  type = " + type + ";");
    out.println("  value =");
    out.println(Util.hexDump(value, "    "));
    out.println("} Extension;");
    return str.toString();
  }

  // Inner class.
  // -------------------------------------------------------------------------

  static final class Type implements Enumerated
  {

    // Constants and fields.
    // -----------------------------------------------------------------------

    static final Type SERVER_NAME            = new Type(0);
    static final Type MAX_FRAGMENT_LENGTH    = new Type(1);
    static final Type CLIENT_CERTIFICATE_URL = new Type(2);
    static final Type TRUSTED_CA_KEYS        = new Type(3);
    static final Type TRUNCATED_HMAC         = new Type(4);
    static final Type STATUS_REQUEST         = new Type(5);
    static final Type SRP                    = new Type(6);
    static final Type CERT_TYPE              = new Type(7);

    private final int value;

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

    private Type(int value)
    {
      this.value = value;
    }

    // Class methods.
    // -----------------------------------------------------------------------

    static Type read(InputStream in) throws IOException
    {
      int i = in.read();
      if (i == -1)
        {
          throw new EOFException("unexpected end of input stream");
        }
      int value = (i & 0xFF) << 8;
      i = in.read();
      if (i == -1)
        {
          throw new EOFException("unexpected end of input stream");
        }
      value |= i & 0xFF;
      switch (value)
        {
        case 0: return SERVER_NAME;
        case 1: return MAX_FRAGMENT_LENGTH;
        case 2: return CLIENT_CERTIFICATE_URL;
        case 3: return TRUSTED_CA_KEYS;
        case 4: return TRUNCATED_HMAC;
        case 5: return STATUS_REQUEST;
        case 6: return SRP;
        case 7: return CERT_TYPE;
        default: return new Type(value);
        }
    }

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

    public byte[] getEncoded()
    {
      return new byte[] {
        (byte) (value >>> 8 & 0xFF), (byte) (value & 0xFF)
      };
    }

    public int getValue()
    {
      return value;
    }

    public String toString()
    {
      switch (value)
        {
        case 0: return "server_name";
        case 1: return "max_fragment_length";
        case 2: return "client_certificate_url";
        case 3: return "trusted_ca_keys";
        case 4: return "truncated_hmac";
        case 5: return "status_request";
        case 6: return "srp";
        case 7: return "cert_type";
        default: return "unknown(" + value + ")";
        }
    }
  }
}