/* ***** 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 "nsISupports.idl"

interface nsICancelable;
interface nsIEventTarget;
interface nsIDNSRecord;
interface nsIDNSListener;

/**
 * nsIDNSService
 */
[scriptable, uuid(c1a56a45-8fa3-44e6-9f01-38c91c858cf9)]
interface nsIDNSService : nsISupports
{
    /**
     * 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 aListenerTarget
     *        optional parameter (may be null).  if non-null, this parameter
     *        specifies the nsIEventTarget 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 An object that can be used to cancel the host lookup.
     */
    nsICancelable asyncResolve(in AUTF8String       aHostName,
                               in unsigned long     aFlags,
                               in nsIDNSListener    aListener,
                               in nsIEventTarget    aListenerTarget);

    /**
     * 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);

    /**
     * if set, the query is given lower priority. Medium takes precedence
     * if both are used.
     */
    const unsigned long RESOLVE_PRIORITY_MEDIUM = (1 << 2);
    const unsigned long RESOLVE_PRIORITY_LOW    = (1 << 3);

    /**
     * if set, indicates request is speculative. Speculative requests 
     * return errors if prefetching is disabled by configuration.
     */
    const unsigned long RESOLVE_SPECULATE = (1 << 4);
};