/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 2003
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Gordon Sheridan <gordon@netscape.com>
 *   IBM Corp.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "nsIDNSRecord.idl"
#include "nsIDNSRequest.idl"
#include "nsIDNSListener.idl"

interface nsIEventQueue;

/**
 * nsIDNSService
 */
[scriptable, uuid(2d6bbf2f-cf97-48f0-af29-642b86d0e59e)]
interface nsIDNSService : nsISupports
{
    /**
     * called to initialize the DNS service.
     */
    void init();

    /**
     * called to shutdown the DNS service.  any pending asynchronous
     * requests will be canceled, and the local cache of DNS records
     * will be cleared.  NOTE: the operating system may still have
     * its own cache of DNS records, which would be unaffected by
     * this method.
     */
    void shutdown();

    /**
     * kicks off an asynchronous host lookup.
     *
     * @param aHostName
     *        the hostname or IP-address-literal to resolve.
     * @param aFlags
     *        a bitwise OR of the RESOLVE_ prefixed constants defined below.
     * @param aListener
     *        the listener to be notified when the result is available.
     * @param aListenerEventQ
     *        optional parameter (may be null).  if non-null, this parameter
     *        specifies the nsIEventQueue of the thread on which the listener's
     *        onLookupComplete should be called.  however, if this parameter is
     *        null, then onLookupComplete will be called on an unspecified
     *        thread (possibly recursively).
     *
     * @return DNS request instance that can be used to cancel the host lookup.
     */
    nsIDNSRequest asyncResolve(in AUTF8String    aHostName,
                               in unsigned long  aFlags,
                               in nsIDNSListener aListener,
                               in nsIEventQueue  aListenerEventQ);

    /**
     * called to synchronously resolve a hostname.  warning this method may
     * block the calling thread for a long period of time.  it is extremely
     * unwise to call this function on the UI thread of an application.
     *
     * @param aHostName
     *        the hostname or IP-address-literal to resolve.
     * @param aFlags
     *        a bitwise OR of the RESOLVE_ prefixed constants defined below.
     *
     * @return DNS record corresponding to the given hostname.
     * @throws NS_ERROR_UNKNOWN_HOST if host could not be resolved.
     */
    nsIDNSRecord resolve(in AUTF8String   aHostName,
                         in unsigned long aFlags);

    /**
     * @return the hostname of the operating system.
     */
    readonly attribute AUTF8String myHostName;

    /*************************************************************************
     * Listed below are the various flags that may be OR'd together to form
     * the aFlags parameter passed to asyncResolve() and resolve().
     */

    /**
     * if set, this flag suppresses the internal DNS lookup cache.
     */
    const unsigned long RESOLVE_BYPASS_CACHE = (1 << 0);

    /**
     * if set, the canonical name of the specified host will be queried.
     */
    const unsigned long RESOLVE_CANONICAL_NAME = (1 << 1);
};