/*
 * @(#)UnresolvedPermission.java	1.24 03/01/23
 *
 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
 
package java.security;

import java.io.IOException;
import java.io.ByteArrayInputStream;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;
import java.lang.reflect.*;
import java.security.cert.*;

/**
 * The UnresolvedPermission class is used to hold Permissions that
 * were "unresolved" when the Policy was initialized. 
 * An unresolved permission is one whose actual Permission class
 * does not yet exist at the time the Policy is initialized (see below).
 * 
 * <p>The policy for a Java runtime (specifying 
 * which permissions are available for code from various principals)
 * is represented by a Policy object.
 * Whenever a Policy is initialized or refreshed, Permission objects of
 * appropriate classes are created for all permissions
 * allowed by the Policy. 
 * 
 * <p>Many permission class types 
 * referenced by the policy configuration are ones that exist
 * locally (i.e., ones that can be found on CLASSPATH).
 * Objects for such permissions can be instantiated during
 * Policy initialization. For example, it is always possible
 * to instantiate a java.io.FilePermission, since the
 * FilePermission class is found on the CLASSPATH.
 * 
 * <p>Other permission classes may not yet exist during Policy
 * initialization. For example, a referenced permission class may
 * be in a JAR file that will later be loaded.
 * For each such class, an UnresolvedPermission is instantiated.
 * Thus, an UnresolvedPermission is essentially a "placeholder"
 * containing information about the permission.
 * 
 * <p>Later, when code calls AccessController.checkPermission 
 * on a permission of a type that was previously unresolved,
 * but whose class has since been loaded, previously-unresolved
 * permissions of that type are "resolved". That is,
 * for each such UnresolvedPermission, a new object of
 * the appropriate class type is instantiated, based on the
 * information in the UnresolvedPermission.
 *
 * <p> To instantiate the new class, UnresolvedPermission assumes
 * the class provides a zero, one, and/or two-argument constructor.
 * The zero-argument constructor would be used to instantiate
 * a permission without a name and without actions.
 * A one-arg constructor is assumed to take a <code>String</code>
 * name as input, and a two-arg constructor is assumed to take a
 * <code>String</code> name and <code>String</code> actions
 * as input.  UnresolvedPermission may invoke a
 * constructor with a <code>null</code> name and/or actions.
 * If an appropriate permission constructor is not available,
 * the UnresolvedPermission is ignored and the relevant permission
 * will not be granted to executing code.
 *
 * <p> The newly created permission object replaces the
 * UnresolvedPermission, which is removed.
 *
 * @see java.security.Permission
 * @see java.security.Permissions
 * @see java.security.PermissionCollection
 * @see java.security.Policy
 *
 * @version 1.24 03/01/23
 *
 * @author Roland Schemers
 */

public final class UnresolvedPermission extends Permission 
implements java.io.Serializable
{
    private static final sun.security.util.Debug debug =
	sun.security.util.Debug.getInstance
	("policy,access", "UnresolvedPermission");

    /**
     * The class name of the Permission class that will be
     * created when this unresolved permission is resolved.
     *
     * @serial
     */
    private String type;

    /**
     * The permission name.
     *
     * @serial
     */
    private String name;

    /**
     * The actions of the permission.
     *
     * @serial
     */
    private String actions;

    private transient java.security.cert.Certificate certs[];

    /**
     * Creates a new UnresolvedPermission containing the permission
     * information needed later to actually create a Permission of the
     * specified class, when the permission is resolved.
     * 
     * @param type the class name of the Permission class that will be
     * created when this unresolved permission is resolved.
     * @param name the name of the permission.
     * @param actions the actions of the permission.
     * @param certs the certificates the permission's class was signed with.
     * This is a list of certificate chains, where each chain is composed of a
     * signer certificate and optionally its supporting certificate chain.
     * Each chain is ordered bottom-to-top (i.e., with the signer certificate
     * first and the (root) certificate authority last).
     */
    public UnresolvedPermission(String type,
				String name,
				String actions,
				java.security.cert.Certificate certs[])
    {
	super(type);

	if (type == null) 
		throw new NullPointerException("type can't be null");

	this.type = type;
	this.name = name;
	this.actions = actions;
	if (certs != null) {
	    // Extract the signer certs from the list of certificates.
	    for (int i=0; i<certs.length; i++) {
		if (!(certs[i] instanceof X509Certificate)) {
		    // there is no concept of signer certs, so we store the
		    // entire cert array
		    this.certs =
			(java.security.cert.Certificate[])certs.clone();
		    break;
		}
	    }

	    if (this.certs == null) {
		// Go through the list of certs and see if all the certs are
		// signer certs.
		int i = 0;
		int count = 0;
		while (i < certs.length) {
		    count++;
		    while (((i+1) < certs.length) &&
			   ((X509Certificate)certs[i]).getIssuerDN().equals(
		               ((X509Certificate)certs[i+1]).getSubjectDN())) {
			i++;
		    }
		    i++;
		}
		if (count == certs.length) {
		    // All the certs are signer certs, so we store the entire
		    // array
		    this.certs =
			(java.security.cert.Certificate[])certs.clone();
		}

		if (this.certs == null) {
		    // extract the signer certs
		    ArrayList signerCerts = new ArrayList();
		    i = 0;
		    while (i < certs.length) {
			signerCerts.add(certs[i]);
			while (((i+1) < certs.length) &&
			    ((X509Certificate)certs[i]).getIssuerDN().equals(
             		      ((X509Certificate)certs[i+1]).getSubjectDN())) {
			    i++;
			}
			i++;
		    }
		    this.certs =
			new java.security.cert.Certificate[signerCerts.size()];
		    signerCerts.toArray(this.certs);
		}
	    }
	}
    }


    private static final Class[] PARAMS0 = { };
    private static final Class[] PARAMS1 = { String.class };
    private static final Class[] PARAMS2 = { String.class, String.class };

    /**
     * try and resolve this permission using the class loader of the permission
     * that was passed in.
     */
    Permission resolve(Permission p, java.security.cert.Certificate certs[]) {
	if (this.certs != null) {
	    // if p wasn't signed, we don't have a match
	    if (certs == null) {
		return null;
	    }

	    // all certs in this.certs must be present in certs
	    boolean match;
	    for (int i = 0; i < this.certs.length; i++) {
		match = false;
		for (int j = 0; j < certs.length; j++) {
		    if (this.certs[i].equals(certs[j])) {
			match = true;
			break;
		    }
		}
		if (!match) return null;
	    }
	}
	try {
	    Class pc = p.getClass();
	    
	    if (name == null && actions == null) {
	        try {
	            Constructor c = pc.getConstructor(PARAMS0);
	    	    return (Permission)c.newInstance(new Object[] {});
		} catch (NoSuchMethodException ne) {
		    try {
		        Constructor c = pc.getConstructor(PARAMS1);
                        return (Permission) c.newInstance(
			      new Object[] { name});
		    } catch (NoSuchMethodException ne1) {
		        Constructor c = pc.getConstructor(PARAMS2);
        		return (Permission) c.newInstance(
			      new Object[] { name, actions });
		    }
		}
	    } else {
	        if (name != null && actions == null) {
	            try {
	                Constructor c = pc.getConstructor(PARAMS1);
                        return (Permission) c.newInstance(
			      new Object[] { name});
		    } catch (NoSuchMethodException ne) {
		        Constructor c = pc.getConstructor(PARAMS2);
        	        return (Permission) c.newInstance(
			      new Object[] { name, actions });
		    }
	        } else {
                    Constructor c = pc.getConstructor(PARAMS2);
                    return (Permission) c.newInstance(
		          new Object[] { name, actions });
	        }
	    }
	} catch (NoSuchMethodException nsme) {
	    if (debug != null ) {
		debug.println("NoSuchMethodException:\n  could not find " +
			"proper constructor for " + type);
		nsme.printStackTrace();
	    }
	    return null;
	} catch (Exception e) {
	    if (debug != null ) {
		debug.println("unable to instantiate " + name);
		e.printStackTrace();
	    }
	    return null;
	}
    }

    /**
     * This method always returns false for unresolved permissions.
     * That is, an UnresolvedPermission is never considered to
     * imply another permission.
     *
     * @param p the permission to check against.
     * 
     * @return false.
     */
    public boolean implies(Permission p) {
	return false;
    }

    /**
     * Checks two UnresolvedPermission objects for equality. 
     * Checks that <i>obj</i> is an UnresolvedPermission, and has 
     * the same type (class) name, permission name, actions, and
     * certificates as this object.
     * 
     * @param obj the object we are testing for equality with this object.
     * 
     * @return true if obj is an UnresolvedPermission, and has the same 
     * type (class) name, permission name, actions, and
     * certificates as this object.
     */
    public boolean equals(Object obj) {
	if (obj == this)
	    return true;

	if (! (obj instanceof UnresolvedPermission))
	    return false;
	UnresolvedPermission that = (UnresolvedPermission) obj;

	// check type
	if (!this.type.equals(that.type)) {
	    return false;
	}

	// check name
	if (this.name == null) {
	    if (that.name != null) {
		return false;
	    }
	} else if (!this.name.equals(that.name)) {
	    return false;
	}

	// check actions
	if (this.actions == null) {
	    if (that.actions != null) {
		return false;
	    }
	} else {
	    if (!this.actions.equals(that.actions)) {
		return false;
	    }
	}

	// check certs
	if ((this.certs == null && that.certs != null) ||
	    (this.certs != null && that.certs == null) ||
	    (this.certs != null && that.certs != null &&
		this.certs.length != that.certs.length)) {
	    return false;
	}
	    
	int i,j;
	boolean match;

	for (i = 0; this.certs != null && i < this.certs.length; i++) {
	    match = false;
	    for (j = 0; j < that.certs.length; j++) {
		if (this.certs[i].equals(that.certs[j])) {
		    match = true;
		    break;
		}
	    }
	    if (!match) return false;
	}

	for (i = 0; that.certs != null && i < that.certs.length; i++) {
	    match = false;
	    for (j = 0; j < this.certs.length; j++) {
		if (that.certs[i].equals(this.certs[j])) {
		    match = true;
		    break;
		}
	    }
	    if (!match) return false;
	}
	return true;
    }

    /**
     * Returns the hash code value for this object.
     *
     * @return a hash code value for this object.
     */

    public int hashCode() {
	int hash = type.hashCode();
	if (name != null)
	    hash ^= name.hashCode();
	if (actions != null)
	    hash ^= actions.hashCode();
	return hash;
    }

    /**
     * Returns the canonical string representation of the actions,
     * which currently is the empty string "", since there are no actions for 
     * an UnresolvedPermission. That is, the actions for the
     * permission that will be created when this UnresolvedPermission
     * is resolved may be non-null, but an UnresolvedPermission
     * itself is never considered to have any actions.
     *
     * @return the empty string "".
     */
    public String getActions()
    {
	return "";
    }

    /**
     * Returns a string describing this UnresolvedPermission.  The convention 
     * is to specify the class name, the permission name, and the actions, in
     * the following format: '(unresolved "ClassName" "name" "actions")'.
     * 
     * @return information about this UnresolvedPermission.
     */
    public String toString() {
	return "(unresolved " + type + " " + name + " " + actions + ")";
    }

    /**
     * Returns a new PermissionCollection object for storing 
     * UnresolvedPermission  objects.
     * <p>
     * @return a new PermissionCollection object suitable for 
     * storing UnresolvedPermissions.
     */

    public PermissionCollection newPermissionCollection() {
	return new UnresolvedPermissionCollection();
    }

    /**
     * Writes this object out to a stream (i.e., serializes it).
     *
     * @serialData An initial <code>String</code> denoting the
     * <code>type</code> is followed by a <code>String</code> denoting the
     * <code>name</code> is followed by a <code>String</code> denoting the
     * <code>actions</code> is followed by an <code>int</code> indicating the
     * number of certificates to follow 
     * (a value of "zero" denotes that there are no certificates associated
     * with this object).
     * Each certificate is written out starting with a <code>String</code>
     * denoting the certificate type, followed by an
     * <code>int</code> specifying the length of the certificate encoding,
     * followed by the certificate encoding itself which is written out as an
     * array of bytes.
     */
    private synchronized void writeObject(java.io.ObjectOutputStream oos)
        throws IOException
    {
	oos.defaultWriteObject();

	if (certs==null || certs.length==0) {
	    oos.writeInt(0);
	} else {
	    // write out the total number of certs
	    oos.writeInt(certs.length);
	    // write out each cert, including its type
	    for (int i=0; i < certs.length; i++) {
		java.security.cert.Certificate cert = certs[i];
		try {
		    oos.writeUTF(cert.getType());
		    byte[] encoded = cert.getEncoded();
		    oos.writeInt(encoded.length);
		    oos.write(encoded);
		} catch (CertificateEncodingException cee) {
		    throw new IOException(cee.getMessage());
		}
	    }
	}
    }

    /**
     * Restores this object from a stream (i.e., deserializes it).
     */
    private synchronized void readObject(java.io.ObjectInputStream ois)
	throws IOException, ClassNotFoundException
    {
	CertificateFactory cf;
	Hashtable cfs=null;

	ois.defaultReadObject();

	if (type == null) 
		throw new NullPointerException("type can't be null");

	// process any new-style certs in the stream (if present)
	int size = ois.readInt();
	if (size > 0) {
	    // we know of 3 different cert types: X.509, PGP, SDSI, which
	    // could all be present in the stream at the same time
	    cfs = new Hashtable(3);
	    this.certs = new java.security.cert.Certificate[size];
	}

	for (int i=0; i<size; i++) {
	    // read the certificate type, and instantiate a certificate
	    // factory of that type (reuse existing factory if possible)
	    String certType = ois.readUTF();
	    if (cfs.containsKey(certType)) {
		// reuse certificate factory
		cf = (CertificateFactory)cfs.get(certType);
	    } else {
		// create new certificate factory
		try {
		    cf = CertificateFactory.getInstance(certType);
		} catch (CertificateException ce) {
		    throw new ClassNotFoundException
			("Certificate factory for "+certType+" not found");
		}
		// store the certificate factory so we can reuse it later
		cfs.put(certType, cf);
	    }
	    // parse the certificate
	    byte[] encoded=null;
	    try {
		encoded = new byte[ois.readInt()];
	    } catch (OutOfMemoryError oome) {
		throw new IOException("Certificate too big");
	    }
	    ois.readFully(encoded);
	    ByteArrayInputStream bais = new ByteArrayInputStream(encoded);
	    try {
		this.certs[i] = cf.generateCertificate(bais);
	    } catch (CertificateException ce) {
		throw new IOException(ce.getMessage());
	    }
	    bais.close();
	}
    }
}