Subversion Repositories openrisc

package gnu.javax.net.ssl.provider;

import java.io.PrintWriter;

import java.io.StringWriter;

import java.nio.ByteBuffer;

import java.nio.ByteOrder;

import java.util.ConcurrentModificationException;

import java.util.Iterator;

import java.util.List;

import java.util.ListIterator;

import java.util.NoSuchElementException;

/**

 * A list of extensions, that may appear in either the {@link ClientHello} or

 * {@link ServerHello}. The form of the extensions list is:

 *

 * <tt>   Extension extensions_list&lt;1..2^16-1&gt;</tt>

 *

 * @author csm

 */

public class ExtensionList implements Builder, Iterable<Extension>

{

  private final ByteBuffer buffer;

  private int modCount;

  public ExtensionList (ByteBuffer buffer)

  {

    this.buffer = buffer.duplicate().order(ByteOrder.BIG_ENDIAN);

    modCount = 0;

  }

  public ExtensionList(List<Extension> extensions)

  {

    int length = 2;

    for (Extension extension : extensions)

      length += extension.length();

    buffer = ByteBuffer.allocate(length);

    buffer.putShort((short) (length - 2));

    for (Extension extension : extensions)

      buffer.put(extension.buffer());

    buffer.rewind();

  }

  public ByteBuffer buffer()

  {

    return (ByteBuffer) buffer.duplicate().limit(length());

  }

  public Extension get (final int index)

  {

    int length = length ();

    int i;

    int n = 0;

    for (i = 2; i < length && n < index; )

      {

        int l = buffer.getShort (i+2) & 0xFFFF;

        i += l + 4;

        n++;

      }

    if (n < index)

      throw new IndexOutOfBoundsException ("no elemenet at " + index);

    int el = buffer.getShort (i+2) & 0xFFFF;

    ByteBuffer b = (ByteBuffer) buffer.duplicate().position(i).limit(i+el+4);

    return new Extension(b.slice());

  }

  /**

   * Returns the number of extensions this list contains.

   *

   * @return The number of extensions.

   */

  public int size ()

  {

    int length = length ();

    if (length == 0)

      return 0;

    int n = 0;

    for (int i = 2; i < length; )

      {

        int len = buffer.getShort (i+2) & 0xFFFF;

        i += len + 4;

        n++;

      }

    return n;

  }

  /**

   * Returns the length of this extension list, in bytes.

   *

   * @return The length of this extension list, in bytes.

   */

  public int length ()

  {

    return (buffer.getShort (0) & 0xFFFF) + 2;

  }

  /**

   * Sets the extension at index <i>i</i> to <i>e</i>. Note that setting an

   * element at an index <b>may</b> invalidate any other elements that come

   * after element at index <i>i</i>. In other words, no attempt is made to

   * move existing elements in this list, and since extensions are variable

   * length, you can <em>not</em> guarantee that extensions later in the list

   * will still be valid.

   *

   * <p>Thus, elements of this list <b>must</b> be set in order of increasing

   * index.

   *

   * @param index The index to set the extension at.

   * @param e The extension.

   * @throws java.nio.BufferOverflowException If setting the extension overflows

   *  the buffer.

   * @throws IllegalArgumentException If it isn't possible to find the given index

   *  in the current list (say, if no element index - 1 is set), or if setting

   *  the extension will overflow the current list length (given by {@link

   *  #length()}).

   */

  public void set (final int index, Extension e)

  {

    int length = length();

    int n = 0;

    int i;

    for (i = 2; i < length && n < index; )

      {

        int len = buffer.getShort(i+2) & 0xFFFF;

        i += len + 4;

        n++;

      }

    if (n < index)

      throw new IllegalArgumentException("nothing set at index " + (index-1)

                                         + " or insufficient space");

    if (i + e.length() + 2 > length)

      throw new IllegalArgumentException("adding this element will exceed the "

                                         + "list length");

    buffer.putShort(i, (short) e.type().getValue());

    buffer.putShort(i+2, (short) e.length());

    ((ByteBuffer) buffer.duplicate().position(i+4)).put (e.valueBuffer());

    modCount++;

  }

  /**

   * Reserve space for an extension at index <i>i</i> in the list. In other

   * words, this does the job of {@link #set(int, Extension)}, but does not

   * copy the extension value to the underlying buffer.

   *

   * @param index The index of the extension to reserve space for.

   * @param t The type of the extension.

   * @param eLength The number of bytes to reserve for this extension. The total

   *  number of bytes used by this method is this length, plus four.

   */

  public void set (final int index, Extension.Type t, final int eLength)

  {

    int length = length ();

    int n = 0;

    int i;

    for (i = 2; i < length && n < index; )

      {

        int len = buffer.getShort (i+2) & 0xFFFF;

        i += len + 4;

        n++;

      }

    if (n < index)

      throw new IllegalArgumentException ("nothing set at index " + (index-1)

                                          + " or insufficient space");

    if (i + eLength + 2 > length)

      throw new IllegalArgumentException ("adding this element will exceed the "

                                          + "list length");

    buffer.putShort(i, (short) t.getValue());

    buffer.putShort(i+2, (short) eLength);

    modCount++;

  }

  /**

   * Set the total length of this list, in bytes.

   *

   * @param newLength The new list length.

   */

  public void setLength (final int newLength)

  {

    if (newLength < 0 || newLength > 65535)

      throw new IllegalArgumentException ("invalid length");

    buffer.putShort (0, (short) newLength);

    modCount++;

  }

  public Iterator<Extension> iterator()

  {

    return new ExtensionsIterator();

  }

  public String toString()

  {

    return toString (null);

  }

  public String toString(final String prefix)

  {

    StringWriter str = new StringWriter();

    PrintWriter out = new PrintWriter(str);

    if (prefix != null) out.print(prefix);

    out.println("ExtensionList {");

    if (prefix != null) out.print(prefix);

    out.print("  length = ");

    out.print(length());

    out.println(";");

    String subprefix = "  ";

    if (prefix != null)

      subprefix = prefix + subprefix;

    for (Extension e : this)

      out.println(e.toString(subprefix));

    if (prefix != null) out.print(prefix);

    out.print("};");

    return str.toString();

  }

  /**

   * List iterator interface to an extensions list.

   *

   * @author csm@gnu.org

   */

  public final class ExtensionsIterator implements ListIterator<Extension>

  {

    private final int modCount;

    private int index;

    private final int size;

    public ExtensionsIterator ()

    {

      this.modCount = ExtensionList.this.modCount;

      index = 0;

      size = size ();

    }

    public boolean hasNext()

    {

      return index < size;

    }

    public boolean hasPrevious()

    {

      return index > 0;

    }

    public Extension next() throws NoSuchElementException

    {

      if (modCount != ExtensionList.this.modCount)

        throw new ConcurrentModificationException ();

      if (!hasNext ())

        throw new NoSuchElementException ();

      return get (index++);

    }

    public Extension previous() throws NoSuchElementException

    {

      if (modCount != ExtensionList.this.modCount)

        throw new ConcurrentModificationException ();

      if (!hasPrevious ())

        throw new NoSuchElementException ();

      return get (--index);

    }

    public int nextIndex()

    {

      if (hasNext ())

        return index + 1;

      return index;

    }

    public int previousIndex()

    {

      if (hasPrevious ())

        return index - 1;

      return -1;

    }

    public void add(Extension e)

    {

      throw new UnsupportedOperationException ("cannot add items to this iterator");

    }

    public void remove()

    {

      throw new UnsupportedOperationException ("cannot remove items from this iterator");

    }

    public void set(Extension e)

    {

      ExtensionList.this.set (index, e);

    }

  }

}