/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * particular file as subject to the "Classpath" exception as provided

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 */

package com.sun.jndi.dns;

import java.util.Enumeration;

import java.util.Hashtable;

import javax.naming.*;

import javax.naming.directory.*;

import javax.naming.spi.DirectoryManager;

import com.sun.jndi.toolkit.ctx.*;

/**

 * A DnsContext is a directory context representing a DNS node.

 *

 * @author Scott Seligman

 */

public class DnsContext extends ComponentDirContext {

    DnsName domain;             // fully-qualified domain name of this context,

                                // with a root (empty) label at position 0

    Hashtable environment;

    private boolean envShared;  // true if environment is possibly shared

                                // and so must be copied on write

    private boolean parentIsDns;        // was this DnsContext created by

                                        // another?  see composeName()

    private String[] servers;

    private Resolver resolver;

    private boolean authoritative;      // must all responses be authoritative?

    private boolean recursion;          // request recursion on queries?

    private int timeout;                // initial timeout on UDP queries in ms

    private int retries;                // number of UDP retries

    static final NameParser nameParser = new DnsNameParser();

    // Timeouts for UDP queries use exponential backoff:  each retry

    // is for twice as long as the last.  The following constants set

    // the defaults for the initial timeout (in ms) and the number of

    // retries, and name the environment properties used to override

    // these defaults.

    private static final int DEFAULT_INIT_TIMEOUT = 1000;

    private static final int DEFAULT_RETRIES = 4;

    private static final String INIT_TIMEOUT =

                                          "com.sun.jndi.dns.timeout.initial";

    private static final String RETRIES = "com.sun.jndi.dns.timeout.retries";

    // The resource record type and class to use for lookups, and the

    // property used to modify them

    private CT lookupCT;

    private static final String LOOKUP_ATTR = "com.sun.jndi.dns.lookup.attr";

    // Property used to disallow recursion on queries

    private static final String RECURSION = "com.sun.jndi.dns.recursion";

    // ANY == ResourceRecord.QCLASS_STAR == ResourceRecord.QTYPE_STAR

    private static final int ANY = ResourceRecord.QTYPE_STAR;

    // The zone tree used for list operations

    private static final ZoneNode zoneTree = new ZoneNode(null);

    /**

     * Returns a DNS context for a given domain and servers.

     * Each server is of the form "server[:port]".

     * IPv6 literal host names include delimiting brackets.

     * There must be at least one server.

     * The environment must not be null; it is cloned before being stored.

     */

    public DnsContext(String domain, String[] servers, Hashtable environment)

            throws NamingException {

        this.domain = new DnsName(domain.endsWith(".")

                                  ? domain

                                  : domain + ".");

        this.servers = servers;

        this.environment = (Hashtable) environment.clone();

        envShared = false;

        parentIsDns = false;

        resolver = null;

        initFromEnvironment();

    }

    /*

     * Returns a clone of a DNS context, just like DnsContext(DnsContext)

     * but with a different domain name and with parentIsDns set to true.

     */

    DnsContext(DnsContext ctx, DnsName domain) {

        this(ctx);

        this.domain = domain;

        parentIsDns = true;

    }

    /*

     * Returns a clone of a DNS context.  The context's modifiable

     * private state is independent of the original's (so closing one

     * context, for example, won't close the other).  The two contexts

     * share <tt>environment</tt>, but it's copy-on-write so there's

     * no conflict.

     */

    private DnsContext(DnsContext ctx) {

        environment = ctx.environment;

        envShared = ctx.envShared = true;

        parentIsDns = ctx.parentIsDns;

        domain = ctx.domain;

        servers = ctx.servers;

        resolver = ctx.resolver;

        authoritative = ctx.authoritative;

        recursion = ctx.recursion;

        timeout = ctx.timeout;

        retries = ctx.retries;

        lookupCT = ctx.lookupCT;

    }

    public void close() {

        if (resolver != null) {

            resolver.close();

            resolver = null;

        }

    }

    //---------- Environment operations

    /*

     * Override default with a noncloning version.

     */

    protected Hashtable p_getEnvironment() {

        return environment;

    }

    public Hashtable getEnvironment() throws NamingException {

        return (Hashtable) environment.clone();

    }

    public Object addToEnvironment(String propName, Object propVal)

            throws NamingException {

        if (propName.equals(LOOKUP_ATTR)) {

            lookupCT = getLookupCT((String) propVal);

        } else if (propName.equals(Context.AUTHORITATIVE)) {

            authoritative = "true".equalsIgnoreCase((String) propVal);

        } else if (propName.equals(RECURSION)) {

            recursion = "true".equalsIgnoreCase((String) propVal);

        } else if (propName.equals(INIT_TIMEOUT)) {

            int val = Integer.parseInt((String) propVal);

            if (timeout != val) {

                timeout = val;

                resolver = null;

            }

        } else if (propName.equals(RETRIES)) {

            int val = Integer.parseInt((String) propVal);

            if (retries != val) {

                retries = val;

                resolver = null;

            }

        }

        if (!envShared) {

            return environment.put(propName, propVal);

        } else if (environment.get(propName) != propVal) {

            // copy on write

            environment = (Hashtable) environment.clone();

            envShared = false;

            return environment.put(propName, propVal);

        } else {

            return propVal;

        }

    }

    public Object removeFromEnvironment(String propName)

            throws NamingException {

        if (propName.equals(LOOKUP_ATTR)) {

            lookupCT = getLookupCT(null);

        } else if (propName.equals(Context.AUTHORITATIVE)) {

            authoritative = false;

        } else if (propName.equals(RECURSION)) {

            recursion = true;

        } else if (propName.equals(INIT_TIMEOUT)) {

            if (timeout != DEFAULT_INIT_TIMEOUT) {

                timeout = DEFAULT_INIT_TIMEOUT;

                resolver = null;

            }

        } else if (propName.equals(RETRIES)) {

            if (retries != DEFAULT_RETRIES) {

                retries = DEFAULT_RETRIES;

                resolver = null;

            }

        }

        if (!envShared) {

            return environment.remove(propName);

        } else if (environment.get(propName) != null) {

            // copy-on-write

            environment = (Hashtable) environment.clone();

            envShared = false;

            return environment.remove(propName);

        } else {

            return null;

        }

    }

    /*

     * Update PROVIDER_URL property.  Call this only when environment

     * is not being shared.

     */

    void setProviderUrl(String url) {

        // assert !envShared;

        environment.put(Context.PROVIDER_URL, url);

    }

    /*

     * Read environment properties and set parameters.

     */

    private void initFromEnvironment()

            throws InvalidAttributeIdentifierException {

        lookupCT = getLookupCT((String) environment.get(LOOKUP_ATTR));

        authoritative = "true".equalsIgnoreCase((String)

                                       environment.get(Context.AUTHORITATIVE));

        String val = (String) environment.get(RECURSION);

        recursion = ((val == null) ||

                     "true".equalsIgnoreCase(val));

        val = (String) environment.get(INIT_TIMEOUT);

        timeout = (val == null)

            ? DEFAULT_INIT_TIMEOUT

            : Integer.parseInt(val);

        val = (String) environment.get(RETRIES);

        retries = (val == null)

            ? DEFAULT_RETRIES

            : Integer.parseInt(val);

    }

    private CT getLookupCT(String attrId)

            throws InvalidAttributeIdentifierException {

        return (attrId == null)

            ? new CT(ResourceRecord.CLASS_INTERNET, ResourceRecord.TYPE_TXT)

            : fromAttrId(attrId);

    }

    //---------- Naming operations

    public Object c_lookup(Name name, Continuation cont)

            throws NamingException {

        cont.setSuccess();

        if (name.isEmpty()) {

            DnsContext ctx = new DnsContext(this);

            ctx.resolver = new Resolver(servers, timeout, retries);

                                                // clone for parallelism

            return ctx;

        }

        try {

            DnsName fqdn = fullyQualify(name);

            ResourceRecords rrs =

                getResolver().query(fqdn, lookupCT.rrclass, lookupCT.rrtype,

                                    recursion, authoritative);

            Attributes attrs = rrsToAttrs(rrs, null);

            DnsContext ctx = new DnsContext(this, fqdn);

            return DirectoryManager.getObjectInstance(ctx, name, this,

                                                      environment, attrs);

        } catch (NamingException e) {

            cont.setError(this, name);

            throw cont.fillInException(e);

        } catch (Exception e) {

            cont.setError(this, name);

            NamingException ne = new NamingException(

                    "Problem generating object using object factory");

            ne.setRootCause(e);

            throw cont.fillInException(ne);

        }

    }

    public Object c_lookupLink(Name name, Continuation cont)

            throws NamingException {

        return c_lookup(name, cont);

    }

    public NamingEnumeration c_list(Name name, Continuation cont)

            throws NamingException {

        cont.setSuccess();

        try {

            DnsName fqdn = fullyQualify(name);

            NameNode nnode = getNameNode(fqdn);

            DnsContext ctx = new DnsContext(this, fqdn);

            return new NameClassPairEnumeration(ctx, nnode.getChildren());

        } catch (NamingException e) {

            cont.setError(this, name);

            throw cont.fillInException(e);

        }

    }

    public NamingEnumeration c_listBindings(Name name, Continuation cont)

            throws NamingException {

        cont.setSuccess();

        try {

            DnsName fqdn = fullyQualify(name);

            NameNode nnode = getNameNode(fqdn);

            DnsContext ctx = new DnsContext(this, fqdn);

            return new BindingEnumeration(ctx, nnode.getChildren());

        } catch (NamingException e) {

            cont.setError(this, name);

            throw cont.fillInException(e);

        }

    }

    public void c_bind(Name name, Object obj, Continuation cont)

            throws NamingException {

        cont.setError(this, name);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    public void c_rebind(Name name, Object obj, Continuation cont)

            throws NamingException {

        cont.setError(this, name);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    public void c_unbind(Name name, Continuation cont)

            throws NamingException {

        cont.setError(this, name);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    public void c_rename(Name oldname, Name newname, Continuation cont)

            throws NamingException {

        cont.setError(this, oldname);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    public Context c_createSubcontext(Name name, Continuation cont)

            throws NamingException {

        cont.setError(this, name);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    public void c_destroySubcontext(Name name, Continuation cont)

            throws NamingException {

        cont.setError(this, name);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    public NameParser c_getNameParser(Name name, Continuation cont)

            throws NamingException {

        cont.setSuccess();

        return nameParser;

    }

    //---------- Directory operations

    public void c_bind(Name name,

                       Object obj,

                       Attributes attrs,

                       Continuation cont)

            throws NamingException {

        cont.setError(this, name);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    public void c_rebind(Name name,

                         Object obj,

                         Attributes attrs,

                         Continuation cont)

            throws NamingException {

        cont.setError(this, name);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    public DirContext c_createSubcontext(Name name,

                                         Attributes attrs,

                                         Continuation cont)

            throws NamingException {

        cont.setError(this, name);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    public Attributes c_getAttributes(Name name,

                                      String[] attrIds,

                                      Continuation cont)

            throws NamingException {

        cont.setSuccess();

        try {

            DnsName fqdn = fullyQualify(name);

            CT[] cts = attrIdsToClassesAndTypes(attrIds);

            CT ct = getClassAndTypeToQuery(cts);

            ResourceRecords rrs =

                getResolver().query(fqdn, ct.rrclass, ct.rrtype,

                                    recursion, authoritative);

            return rrsToAttrs(rrs, cts);

        } catch (NamingException e) {

            cont.setError(this, name);

            throw cont.fillInException(e);

        }

    }

    public void c_modifyAttributes(Name name,

                                   int mod_op,

                                   Attributes attrs,

                                   Continuation cont)

            throws NamingException {

        cont.setError(this, name);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    public void c_modifyAttributes(Name name,

                                   ModificationItem[] mods,

                                   Continuation cont)

            throws NamingException {

        cont.setError(this, name);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    public NamingEnumeration c_search(Name name,

                                      Attributes matchingAttributes,

                                      String[] attributesToReturn,

                                      Continuation cont)

            throws NamingException {

        throw new OperationNotSupportedException();

    }

    public NamingEnumeration c_search(Name name,

                                      String filter,

                                      SearchControls cons,

                                      Continuation cont)

            throws NamingException {

        throw new OperationNotSupportedException();

    }

    public NamingEnumeration c_search(Name name,

                                      String filterExpr,

                                      Object[] filterArgs,

                                      SearchControls cons,

                                      Continuation cont)

            throws NamingException {

        throw new OperationNotSupportedException();

    }

    public DirContext c_getSchema(Name name, Continuation cont)

            throws NamingException {

        cont.setError(this, name);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    public DirContext c_getSchemaClassDefinition(Name name, Continuation cont)

            throws NamingException {

        cont.setError(this, name);

        throw cont.fillInException(

                new OperationNotSupportedException());

    }

    //---------- Name-related operations

    public String getNameInNamespace() {

        return domain.toString();

    }

    public Name composeName(Name name, Name prefix) throws NamingException {

        Name result;

        // Any name that's not a CompositeName is assumed to be a DNS

        // compound name.  Convert each to a DnsName for syntax checking.

        if (!(prefix instanceof DnsName || prefix instanceof CompositeName)) {

            prefix = (new DnsName()).addAll(prefix);

        }

        if (!(name instanceof DnsName || name instanceof CompositeName)) {

            name = (new DnsName()).addAll(name);

        }

        // Each of prefix and name is now either a DnsName or a CompositeName.

        // If we have two DnsNames, simply join them together.

        if ((prefix instanceof DnsName) && (name instanceof DnsName)) {

            result = (DnsName) (prefix.clone());

            result.addAll(name);

            return new CompositeName().add(result.toString());

        }

        // Wrap compound names in composite names.

        Name prefixC = (prefix instanceof CompositeName)