alwaysaccessservice.java

jxta平台的开发包

/*
 *  Copyright (c) 2003 Sun Microsystems, Inc.  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *  notice, this list of conditions and the following disclaimer.
 *
 *  2. Redistributions in binary form must reproduce the above copyright
 *  notice, this list of conditions and the following disclaimer in
 *  the documentation and/or other materials provided with the
 *  distribution.
 *
 *  3. The end-user documentation included with the redistribution,
 *  if any, must include the following acknowledgment:
 *  "This product includes software developed by the
 *  Sun Microsystems, Inc. for Project JXTA."
 *  Alternately, this acknowledgment may appear in the software itself,
 *  if and wherever such third-party acknowledgments normally appear.
 *
 *  4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA"
 *  must not be used to endorse or promote products derived from this
 *  software without prior written permission. For written
 *  permission, please contact Project JXTA at http://www.jxta.org.
 *
 *  5. Products derived from this software may not be called "JXTA",
 *  nor may "JXTA" appear in their name, without prior written
 *  permission of Sun.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR
 *  ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 *  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 *  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 *  SUCH DAMAGE.
 *  ====================================================================
 *
 *  This software consists of voluntary contributions made by many
 *  individuals on behalf of Project JXTA.  For more
 *  information on Project JXTA, please see
 *  <http://www.jxta.org/>.
 *
 *  This license is based on the BSD license adopted by the Apache Foundation.
 *
 * $Id: AlwaysAccessService.java,v 1.4 2006/06/02 18:35:43 bondolo Exp $
 */
package net.jxta.impl.access.always;

import java.net.URI;
import java.util.Enumeration;

import java.net.URISyntaxException;

import org.apache.log4j.Logger;
import org.apache.log4j.Level;

import net.jxta.access.AccessService;
import net.jxta.credential.Credential;
import net.jxta.credential.PrivilegedOperation;
import net.jxta.document.Advertisement;
import net.jxta.document.Attributable;
import net.jxta.document.Attribute;
import net.jxta.document.Element;
import net.jxta.document.MimeMediaType;
import net.jxta.document.StructuredDocument;
import net.jxta.document.StructuredDocumentFactory;
import net.jxta.document.StructuredDocumentUtils;
import net.jxta.document.TextElement;
import net.jxta.exception.PeerGroupException;
import net.jxta.id.ID;
import net.jxta.id.IDFactory;
import net.jxta.peergroup.PeerGroup;
import net.jxta.protocol.ModuleImplAdvertisement;
import net.jxta.service.Service;


/**
 * A minimal {@link net.jxta.access.AccessService} implementation.
 *
 * <p/><code>doAccessCheck</code> will return <code>PERMITTED</code> to all
 * queries when provided any valid credential and operation.
 *
 * <p/>If the subject of the Credential or the operation is equivalent to the
 * String "DENY" then the operation will be <code>DISALLOWED</code>.
 *
 * @see net.jxta.access.AccessService
 **/
public class AlwaysAccessService implements AccessService {
    
    /**
     *  log4J Logger
     **/
    private final static Logger LOG = Logger.getLogger( AlwaysAccessService.class.getName() );
    
    
    /**
     *  Operation for the Always Access Service.
     **/
    private static class AlwaysOperation implements PrivilegedOperation {
        
        AlwaysAccessService source;
        
        String op;
        
        Credential offerer;
        
        protected AlwaysOperation( AlwaysAccessService source, String op, Credential offerer ) {
            this.source = source;
            this.op = op;
            this.offerer = offerer;
        }
        
        protected AlwaysOperation( AlwaysAccessService source, Element root ) {
            this.source = source;
            initialize( root );
        }
        
        /**
         * {@inheritDoc}
         **/
        public ID getPeerGroupID() {
            return source.getPeerGroup().getPeerGroupID();
        }
        
        /**
         * {@inheritDoc}
         **/
        public ID getPeerID() {
            return null;
        }
        
        /**
         * {@inheritDoc}
         *
         * <p/>AlwaysOperation are always valid.
         **/
        public boolean isExpired() {
            return false;
        }
        
        /**
         * {@inheritDoc}
         *
         * <p/>AlwaysOperation are always valid.
         **/
        public boolean isValid() {
            return true;
        }
        
        /**
         * {@inheritDoc}
         **/
        public Object getSubject() {
            return op;
        }
        
        /**
         * {@inheritDoc}
         **/
        public Service getSourceService() {
            return source;
        }
        
        /**
         * {@inheritDoc}
         **/
        public StructuredDocument getDocument(MimeMediaType as) throws Exception {
            StructuredDocument doc = StructuredDocumentFactory.newStructuredDocument( as, "jxta:Cred" );
            
            if( doc instanceof Attributable ) {
                ((Attributable)doc).addAttribute( "xmlns:jxta", "http://jxta.org" );
                ((Attributable)doc).addAttribute( "xml:space", "preserve" );
                ((Attributable)doc).addAttribute( "type", "jxta:AlwaysOp" );
            }
            
            Element e = doc.createElement( "PeerGroupID", getPeerGroupID().toString() );
            doc.appendChild( e );
            
            e = doc.createElement( "Operation", op );
            doc.appendChild( e );
            
            StructuredDocumentUtils.copyElements( doc, doc, offerer.getDocument( as ), "Offerer" );
            
            return doc;
        }
        
        /**
         * {@inheritDoc}
         **/
        public Credential getOfferer() {
            return offerer;
        }
        
        /**
         *  Process an individual element from the document.
         *
         *  @param elem the element to be processed.
         *  @return true if the element was recognized, otherwise false.
         **/
        protected boolean handleElement( TextElement elem ) {
            if( elem.getName().equals("PeerGroupID")) {
                try {
                    URI gID = new URI( elem.getTextValue().trim() );
                    ID pgid = IDFactory.fromURI( gID );
                    if( !pgid.equals( getPeerGroupID() ) ) {
                        throw new IllegalArgumentException( "Operation is from a different group. " + pgid + " != " + getPeerGroupID() );
                    }
                } catch ( URISyntaxException badID ) {
                    throw new IllegalArgumentException( "Bad ID in advertisement: " + elem.getTextValue() );
                } catch ( ClassCastException badID ) {
                    throw new IllegalArgumentException( "Id is not a group id: " + elem.getTextValue() );
                }
                return true;
            }
            
            if( elem.getName().equals("Operation")) {
                op = elem.getTextValue();
                return true;
            }
            
            if( elem.getName().equals("Offerer")) {
                try {
                offerer = source.getPeerGroup().getMembershipService().makeCredential( elem );
                } catch( Throwable failed ) {
                    throw new IllegalArgumentException( "Offerer credential could not be constructed" + failed );
                }
                return true;
            }
            
            // element was not handled
            return false;
        }
        
        /**
         *  Intialize from a portion of a structured document.
         **/
        protected void initialize( Element root ) {
            
            if( !TextElement.class.isInstance( root ) ) {
                throw new IllegalArgumentException( getClass().getName() + " only supports TextElement" );
            }
            
            TextElement doc = (TextElement) root;
            
            String typedoctype = "";
            if( root instanceof Attributable ) {
                Attribute itsType = ((Attributable)root).getAttribute( "type" );
                if( null != itsType ) {
                    typedoctype = itsType.getValue();
                }
            }
            
            String doctype = doc.getName();
            
            if( !doctype.equals("jxta:AlwaysOp") &&
            !(doctype.equals("jxta:Cred") && "jxta:AlwaysOp".equals(typedoctype)) ) {
                throw new IllegalArgumentException( "Could not construct : "
                + getClass().getName() + "from doc containing a " + doc.getName() );
            }
            
            Enumeration elements = doc.getChildren();
            
            while (elements.hasMoreElements()) {
                TextElement elem = (TextElement) elements.nextElement();
                
                if( !handleElement( elem ) ) {
                    if (LOG.isEnabledFor(Level.WARN)) {
                        LOG.warn("Unhandleded element '" + elem.getName() + "' in " + doc.getName() );
                    }
                };
            }
            
            // sanity check time!
            
            if( null == op ) {
                throw new IllegalArgumentException( "operation was never initialized." );
            }
            
            if( null == offerer ) {
                throw new IllegalArgumentException( "offerer was never initialized." );
            }
        }
    }
    
    PeerGroup group;
    
    ModuleImplAdvertisement implAdvertisement;
    
    /**
     *  Default Constructor
     **/
    public AlwaysAccessService() {
    }
    
    /**
     * {@inheritDoc}
     **/
    public void init( PeerGroup group, ID assignedID, Advertisement implAdv ) throws PeerGroupException {
        implAdvertisement = (ModuleImplAdvertisement) implAdv;
        this.group = group;
        
        if (LOG.isEnabledFor(Level.INFO)) {
            StringBuffer configInfo = new StringBuffer( "Configuring Access Service : " + assignedID );
            
            configInfo.append( "\n\tImplementation:" );
            configInfo.append( "\n\t\tImpl Description: " + implAdvertisement.getDescription() );
            configInfo.append( "\n\t\tImpl URI : " + implAdvertisement.getUri() );
            configInfo.append( "\n\t\tImpl Code : " + implAdvertisement.getCode() );
            
            configInfo.append( "\n\tGroup Params:" );
            configInfo.append( "\n\t\tGroup: " + group.getPeerGroupName() );
            configInfo.append( "\n\t\tGroup ID: " + group.getPeerGroupID() );
            configInfo.append( "\n\t\tPeer ID: " + group.getPeerID() );
            
            LOG.info( configInfo );
        }
    }
    
    /**
     * {@inheritDoc}
     **/
    public int startApp(String[] args) {
        return 0;
    }
    
    /**
     * {@inheritDoc}
     **/
    public void stopApp() {
    }
    
    /**
     * {@inheritDoc}
     **/
    public Advertisement getImplAdvertisement() {
        return implAdvertisement;
    }
    
    /**
     * {@inheritDoc}
     **/
    public Service getInterface() {
        return this;
    }
    
    /**
     * {@inheritDoc}
     **/
    PeerGroup getPeerGroup() {
        return group;
    }
    
    /**
     * {@inheritDoc}
     **/
    public AccessResult doAccessCheck( PrivilegedOperation op, Credential cred ) {
        if( null == cred ) {
            return (null == op) ? AccessResult.PERMITTED : ("DENY".equals( op.getSubject() ) ? AccessResult.DISALLOWED : AccessResult.PERMITTED);
        }
        
        if( !cred.isValid() ) {
            return AccessResult.DISALLOWED;
        }
        
        if( "DENY".equals(cred.getSubject()) ) {
            return AccessResult.DISALLOWED;
        }
        
        if( null == op ) {
            return AccessResult.PERMITTED;
        }
                
        if( !op.isValid() ) {
            return AccessResult.DISALLOWED;
        }
        
        return "DENY".equals( op.getSubject() ) ? AccessResult.DISALLOWED : AccessResult.PERMITTED;
    }
    
    /**
     * {@inheritDoc}
     **/
    public PrivilegedOperation newPrivilegedOperation(Object subject, Credential offerer) {
        if( !(subject instanceof String) ) {
            throw new IllegalArgumentException( getClass().getName() + " only supports String subjects." );
        }
        
        if( !offerer.isValid() ) {
            throw new IllegalArgumentException( "offerer is not a valid credential" );
        }
        
        return new AlwaysOperation( this, (String) subject, offerer );
    }
    
    /**
     * {@inheritDoc}
     **/
    public PrivilegedOperation newPrivilegedOperation(Element source ) {
        return new AlwaysOperation( this, source );
    }
}