/* SocketPermission.java -- Class modeling permissions for socket operations
   Copyright (C) 1998, 2000, 2001 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath 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, or (at your option)
any later version.

GNU Classpath 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 GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

As a special exception, if you link this library with other files to
produce an executable, this library does not by itself cause the
resulting executable to be covered by the GNU General Public License.
This exception does not however invalidate any other reasons why the
executable file might be covered by the GNU General Public License. */

package java.net;

import java.security.Permission;
import java.security.PermissionCollection;

/**
 * This class models a specific set of permssions for connecting to a
 * host.  There are two elements to this, the host/port combination and
 * the permission list.
 * <p>
 * The host/port combination is specified as followed
 * <p>
 * <pre>
 * hostname[:[-]port[-[port]]]
 * </pre>
 * <p>
 * The hostname portion can be either a hostname or IP address.  If it is
 * a hostname, a wildcard is allowed in hostnames.  This wildcard is a "*"
 * and matches one or more characters.  Only one "*" may appear in the
 * host and it must be the leftmost character.  For example,
 * "*.urbanophile.com" matches all hosts in the "urbanophile.com" domain.
 * <p>
 * The port portion can be either a single value, or a range of values
 * treated as inclusive.  The first or the last port value in the range
 * can be omitted in which case either the minimum or maximum legal
 * value for a port (respectively) is used by default.  Here are some
 * examples:
 * <p><ul>
 * <li>8080 - Represents port 8080 only
 * <li>2000-3000 - Represents ports 2000 through 3000 inclusive
 * <li>-4000 - Represents ports 0 through 4000 inclusive
 * <li>1024- - Represents ports 1024 through 65535 inclusive
 * </ul><p>
 * The permission list is a comma separated list of individual permissions.
 * These individual permissions are:
 * <p>
 * accept<br>
 * connect<br>
 * listen<br>
 * resolve<br>
 * <p>
 * The "listen" permission is only relevant if the host is localhost.  If
 * any permission at all is specified, then resolve permission is implied to
 * exist.
 * <p>
 * Here are a variety of examples of how to create SocketPermission's
 * <p><pre>
 * SocketPermission("www.urbanophile.com", "connect");
 *   Can connect to any port on www.urbanophile.com
 * SocketPermission("www.urbanophile.com:80", "connect,accept");
 *   Can connect to or accept connections from www.urbanophile.com on port 80
 * SocketPermission("localhost:1024-", "listen,accept,connect");
 *   Can connect to, accept from, an listen on any local port number 1024 and up.
 * SocketPermission("*.edu", "connect");
 *   Can connect to any host in the edu domain
 * SocketPermission("197.197.20.1", "accept");
 *   Can accept connections from 197.197.20.1
 * </pre><p>
 *
 * @since 1.2
 *
 * @author Aaron M. Renn (arenn@urbanophile.com)
 */
public final class SocketPermission extends Permission
  implements java.io.Serializable
{

// FIXME: Needs serialization work, including readObject/writeObject methods.
  /**
   * A hostname/port combination as described above
   */
  private transient String hostport;

  /**
   * A comma separated list of actions for which we have permission
   */
  private String actions;

  /**
   * Initializes a new instance of <code>SocketPermission</code> with the 
   * specified host/port combination and actions string.
   *
   * @param hostport The hostname/port number combination
   * @param perms The actions string
   */
  public SocketPermission(String hostport, String actions)
  {
    super(hostport);

    this.hostport = hostport;
    this.actions = actions;
  }

  /**
   * Tests this object for equality against another.  This will be true if
   * and only if the passed object is an instance of 
   * <code>SocketPermission</code> and both its hostname/port combination 
   * and permissions string are identical.
   *
   * @param obj The object to test against for equality
   *
   * @return <code>true</code> if object is equal to this object, 
   *         <code>false</code> otherwise.
   */
  public boolean equals(Object obj)
  {
    if (obj == null)
      return (false);

    if (!(obj instanceof SocketPermission))
      return (false);

    if (((SocketPermission) obj).hostport.equals(hostport))
      if (((SocketPermission) obj).actions.equals(actions))
	return (true);

    return (false);
  }

  /**
   * Returns a hash code value for this object.  Overrides the 
   * Permission.hashCode()
   *
   * @return A hash code
   */
  public int hashCode()
  {
    int hash = 100;

    // FIXME: Get a real hash function
    for (int i = 0; i < hostport.length(); i++)
      hash = hash + (int) hostport.charAt(i) * 7;

    return (hash);
  }

  /**
   * Returns the list of permission actions in this object in canonical
   * order.  The canonical order is "connect,listen,accept,resolve"
   *
   * @return The permitted action string.
   */
  public String getActions()
  {
    boolean found = false;
    StringBuffer sb = new StringBuffer("");

    if (actions.indexOf("connect") != -1)
      {
	sb.append("connect");
	found = true;
      }

    if (actions.indexOf("listen") != -1)
      if (found)
	  sb.append(",listen");
      else
	{
	  sb.append("listen");
	  found = true;
	}

    if (actions.indexOf("accept") != -1)
      if (found)
	sb.append(",accept");
      else
	{
	  sb.append("accept");
	  found = true;
	}

    if (found)
      sb.append(",resolve");
    else if (actions.indexOf("resolve") != -1)
      sb.append("resolve");

    return (sb.toString());
  }

  /**
   * Returns a new <code>PermissionCollection</code> object that can hold
   * <code>SocketPermission</code>'s.
   *
   * @return A new <code>PermissionCollection</code>.
   */
  public PermissionCollection newPermissionCollection()
  {
    // FIXME: Implement

    return (null);
  }

  /**
   * Returns true if the permission object passed it is implied by the
   * this permission.  This will be true if 
   * <p><ul>
   * <li>The argument is of type SocketPermission
   * <li>The actions list of the argument are in this object's actions
   * <li>The port range of the argument is within this objects port range
   * <li>The hostname is equal to or a subset of this objects hostname
   * </ul>
   * <p>
   * The argument's hostname will be a subset of this object's hostname if:
   * <p><ul>
   * <li>The argument's hostname or IP address is equal to this object's.
   * <li>The argument's canonical hostname is equal to this object's.
   * <li>The argument's canonical name matches this domains hostname with wildcards
   * </ul>
   *
   * @param perm The Permission to check against
   *
   * @return <code>true</code> if the <code>Permission</code> is implied by 
   * this object, <code>false</code> otherwise.
   */
  public boolean implies(Permission perm)
  {
    SocketPermission p;

    // First make sure we are the right object type
    if (perm instanceof SocketPermission)
      p = (SocketPermission) perm;
    else
      return (false);

    // Next check the actions
    String ourlist = getActions();
    String theirlist = p.getActions();

    if (!ourlist.startsWith(theirlist))
      return (false);

    // Now check ports
    int ourfirstport = 0, ourlastport = 0, theirfirstport = 0, theirlastport =
      0;

    // Get ours
    if (hostport.indexOf(":") == -1)
      {
	ourfirstport = 0;
	ourlastport = 65535;
      }
    else
      {
	// FIXME:  Needs bulletproofing.
	// This will dump if hostport if all sorts of bad data was passed to
	// the constructor
	String range = hostport.substring(hostport.indexOf(":") + 1);
	if (range.startsWith("-"))
	  ourfirstport = 0;
	else if (range.indexOf("-") == -1)
	  ourfirstport = Integer.parseInt(range);
	else
	  ourfirstport =
	    Integer.parseInt(range.substring(0, range.indexOf("-")));

	if (range.endsWith("-"))
	  ourlastport = 65535;
	else if (range.indexOf("-") == -1)
	  ourlastport = Integer.parseInt(range);
	else
	  ourlastport =
	    Integer.parseInt(range.
			     substring(range.indexOf("-") + 1,
				       range.length()));
      }

    // Get theirs
    if (p.hostport.indexOf(":") == -1)
      {
	theirfirstport = 0;
	ourlastport = 65535;
      }
    else
      {
	// This will dump if hostport if all sorts of bad data was passed to
	// the constructor
	String range = p.hostport.substring(hostport.indexOf(":") + 1);
	if (range.startsWith("-"))
	  theirfirstport = 0;
	else if (range.indexOf("-") == -1)
	  theirfirstport = Integer.parseInt(range);
	else
	  theirfirstport =
	    Integer.parseInt(range.substring(0, range.indexOf("-")));

	if (range.endsWith("-"))
	  theirlastport = 65535;
	else if (range.indexOf("-") == -1)
	  theirlastport = Integer.parseInt(range);
	else
	  theirlastport =
	    Integer.parseInt(range.
			     substring(range.indexOf("-") + 1,
				       range.length()));
      }

    // Now check them
    if ((theirfirstport < ourfirstport) || (theirlastport > ourlastport))
      return (false);

    // Finally we can check the hosts
    String ourhost, theirhost;

    // Get ours
    if (hostport.indexOf(":") == -1)
      ourhost = hostport;
    else
      ourhost = hostport.substring(0, hostport.indexOf(":"));

    // Get theirs
    if (p.hostport.indexOf(":") == -1)
      theirhost = p.hostport;
    else
      theirhost = p.hostport.substring(0, p.hostport.indexOf(":"));

    // Are they equal?
    if (ourhost.equals(theirhost))
      return (true);

    // Try the canonical names
    String ourcanonical = null, theircanonical = null;
    try
      {
	ourcanonical = InetAddress.getByName(ourhost).getHostName();
	theircanonical = InetAddress.getByName(theirhost).getHostName();
      }
    catch (UnknownHostException e)
      {
	// Who didn't resolve?  Just assume current address is canonical enough
	// Is this ok to do?
	if (ourcanonical == null)
	  ourcanonical = ourhost;
	if (theircanonical == null)
	  theircanonical = theirhost;
      }

    if (ourcanonical.equals(theircanonical))
      return (true);

    // Well, last chance.  Try for a wildcard
    if (ourhost.indexOf("*.") != -1)
      {
	String wild_domain = ourhost.substring(ourhost.indexOf("*" + 1));
	if (theircanonical.endsWith(wild_domain))
	  return (true);
      }

    // Didn't make it
    return (false);
  }
}