/* ***** 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 Bookmarks Sync.
 *
 * The Initial Developer of the Original Code is Mozilla.
 * Portions created by the Initial Developer are Copyright (C) 2008
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *  Jono DiCarlo <jdicarlo@mozilla.org>
 *
 * 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 ***** */

const EXPORTED_SYMBOLS = [ "PlainAuthenticator", "Md5DigestAuthenticator" ];

var Cc = Components.classes;
var Ci = Components.interfaces;
var Cu = Components.utils;

Cu.import("resource://weave/log4moz.js");

/* Two implementations of SASL authentication:
   one using MD5-DIGEST, the other using PLAIN.


Here's the interface that each implementation must obey:

{
  initialize( clientName, clientRealm, clientPassword );

  generateResponse( rootElem );

  // returns text of error message
  getError();
}

*/

function BaseAuthenticator() {
}
BaseAuthenticator.prototype = {
 COMPLETION_CODE: "success!",

 initialize: function( userName, realm, password  ) {
    this._name = userName;
    this._realm = realm;
    this._password = password;
    this._stepNumber = 0;
    this._errorMsg = "";
 },

 getError: function () {
    /* Returns text of most recent error message.
       Client code should call this if generateResponse() returns false
       to see what the problem was. */
    return this._errorMsg;
 },

 generateResponse: function( rootElem ) {
    /* Subclasses must override this.  rootElem is a DOM node which is
       the root element of the XML the server has sent to us as part
       of the authentication protocol.  return value: the string that
       should be sent back to the server in response.  'false' if
       there's a failure, or COMPLETION_CODE if nothing else needs to
       be sent because authentication is a success. */

    this._errorMsg = "generateResponse() should be overridden by subclass.";
    return false;
 },

 verifyProtocolSupport: function( rootElem, protocolName ) {
    /* Parses the incoming stream from the server to check whether the
       server supports the type of authentication we want to do
       (specified in the protocolName argument).
       Returns false if there is any problem.
     */
    if ( rootElem.nodeName != "stream:stream" ) {
      this._errorMsg = "Expected stream:stream but got " + rootElem.nodeName;
      return false;
    }

    dump( "Got response from server...\n" );
    dump( "ID is " + rootElem.getAttribute( "id" ) + "\n" );
    // TODO: Do I need to do anything with this ID value???
    dump( "From: " + rootElem.getAttribute( "from" ) + "\n" );
    if (rootElem.childNodes.length == 0) {
      // No child nodes is unexpected, but allowed by the protocol.
      // this shouldn't be an error.
      this._errorMsg = "Expected child nodes but got none.";
      return false;
    }

    var child = rootElem.childNodes[0];
    if (child.nodeName == "stream:error" ) {
      this._errorMsg = this.parseError( child );
      return false;
    }

    if ( child.nodeName != "stream:features" ) {
      this._errorMsg = "Expected stream:features but got " + child.nodeName;
      return false;
    }

    var protocolSupported = false;
    var mechanisms = child.getElementsByTagName( "mechanism" );
    for ( var x = 0; x < mechanisms.length; x++ ) {
      if ( mechanisms[x].firstChild.nodeValue == protocolName ) {
	      protocolSupported = true;
      }
    }

    if ( !protocolSupported ) {
      this._errorMsg = protocolName + " not supported by server!";
      return false;
    }
    return true;
 }

};

function Md5DigestAuthenticator( ) {
  /* SASL using DIGEST-MD5 authentication.
     Uses complicated hash of password
     with nonce and cnonce to obscure password while preventing replay
     attacks.

     See http://www.faqs.org/rfcs/rfc2831.html
     "Using Digest Authentication as a SASL mechanism"

     TODO: currently, this is getting rejected by my server.
     What's wrong?
  */
}
Md5DigestAuthenticator.prototype = {

  _makeCNonce: function( ) {
    return "\"" + Math.floor( 10000000000 * Math.random() ) + "\"";
  },

  generateResponse: function Md5__generateResponse( rootElem ) {
    if ( this._stepNumber == 0 ) {

      if ( this.verifyProtocolSupport( rootElem, "DIGEST-MD5" ) == false ) {
        return false;
      }
      // SASL step 1: request that we use DIGEST-MD5 authentication.
      this._stepNumber = 1;
      return "<auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' mechanism='DIGEST-MD5'/>";

    } else if ( this._stepNumber == 1 ) {

      // proceed to SASL step 2: are you asking for a CHALLENGE?!?
      var challenge = this._unpackChallenge( rootElem.firstChild.nodeValue );
      dump( "Nonce is " + challenge.nonce + "\n" );
      // eg:
      // nonce="3816627940",qop="auth",charset=utf-8,algorithm=md5-sess

      // Now i have the nonce: make a digest-response out of
      /* username: required
       realm: only needed if realm is in challenge
       nonce: required, just as recieved
       cnonce: required, opaque quoted string, 64 bits entropy
       nonce-count: optional
       qop: (quality of protection) optional
       serv-type: optional?
       host: optional?
       serv-name: optional?
       digest-uri: "service/host/serv-name" (replaces those three?)
       response: required (32 lowercase hex),
       maxbuf: optional,
       charset,
       LHEX (32 hex digits = ??),
       cipher: required if auth-conf is negotiatedd??
       authzid: optional
      */


      // TODO: Are these acceptable values for realm, nonceCount, and
      // digestUri??
      var nonceCount = "00000001";
      var digestUri = "xmpp/" + this.realm;
      var cNonce = this._makeCNonce();
    // Section 2.1.2.1 of RFC2831
      var A1 = str_md5( this.name + ":" + this.realm + ":" + this.password ) + ":" + challenge.nonce + ":" + cNonce;
      var A2 = "AUTHENTICATE:" + digestUri;
      var myResponse = hex_md5( hex_md5( A1 ) + ":" + challenge.nonce + ":" + nonceCount + ":" + cNonce + ":auth" + hex_md5( A2 ) );

      var responseDict = {
      username: "\"" + this.name + "\"",
      nonce: challenge.nonce,
      nc: nonceCount,
      cnonce: cNonce,
      qop: "\"auth\"",
      algorithm: "md5-sess",
      charset: "utf-8",
      response: myResponse
      };
      responseDict[ "digest-uri" ] = "\"" + digestUri + "\"";
      var responseStr = this._packChallengeResponse( responseDict );
      this._stepNumber = 2;
      return "<response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>" + responseStr + "</response>";

    } else if ( this._stepNumber = 2 ) {
      dump( "Got to step 3!" );
      // At this point the server might reject us with a
      // <failure><not-authorized/></failure>
      if ( rootElem.nodeName == "failure" ) {
        this._errorMsg = rootElem.firstChild.nodeName;
        return false;
      }
      //this._connectionStatus = this.REQUESTED_SASL_3;
    }
    this._errorMsg = "Can't happen.";
    return false;
  },

  _unpackChallenge: function( challengeString ) {
    var challenge = atob( challengeString );
    dump( "After b64 decoding: " + challenge + "\n" );
    var challengeItemStrings = challenge.split( "," );
    var challengeItems = {};
    for ( var x in challengeItemStrings ) {
      var stuff = challengeItemStrings[x].split( "=" );
      challengeItems[ stuff[0] ] = stuff[1];
    }
    return challengeItems;
  },

  _packChallengeResponse: function( responseDict ) {
    var responseArray = []
    for( var x in responseDict ) {
      responseArray.push( x + "=" + responseDict[x] );
    }
    var responseString = responseArray.join( "," );
    dump( "Here's my response string: \n" );
    dump( responseString + "\n" );
    return btoa( responseString );
  }
};
Md5DigestAuthenticator.prototype.__proto__ = new BaseAuthenticator();


function PlainAuthenticator( ) {
  /* SASL using PLAIN authentication, which sends password in the clear. */
}
PlainAuthenticator.prototype = {

  generateResponse: function( rootElem ) {
    if ( this._stepNumber == 0 ) {
      if ( this.verifyProtocolSupport( rootElem, "PLAIN" ) == false ) {
        return false;
      }
      var authString = btoa( this._realm + '\0' + this._name + '\0' + this._password );
      this._stepNumber = 1;

      // XXX why does this not match the stanzas in XEP-025?
      return "<auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' mechanism='PLAIN'>" + authString + "</auth>";

    } else if ( this._stepNumber == 1 ) {
      if ( rootElem.nodeName == "failure" ) {
	      // Authentication rejected: username or password may be wrong.
	      this._errorMsg = rootElem.firstChild.nodeName;
	      return false;
      } else if ( rootElem.nodeName == "success" ) {
        // Authentication accepted: now we start a new stream for
        // resource binding.
        /* RFC3920 part 7 says: upon receiving a success indication  within the
           SASL negotiation, the client MUST send a new stream header to the
           server, to which the serer MUST respond with a stream header
           as well as a list of available stream features. */
        // TODO: resource binding happens in any authentication mechanism
        // so should be moved to base class.
        this._stepNumber = 2;
        return "<?xml version='1.0'?><stream:stream to='" +
               this._realm +
               "' xmlns='jabber:client' xmlns:stream='http://etherx.jabber.org/streams' version='1.0'>";
      }
    } else if ( this._stepNumber == 2 ) {
      // See if the server is asking us to bind a resource, and if it's
      // asking us to start a session:
      var bindNodes = rootElem.getElementsByTagName( "bind" );
      if ( bindNodes.length > 0 ) {
	      this._needBinding = true;
      }

      var sessionNodes = rootElem.getElementsByTagName( "session" );
      if ( sessionNodes.length > 0 ) {
	      this._needSession = true;
      }

      if ( !this._needBinding && !this._needSession ) {
	      // Server hasn't requested either: we're done.
	      return this.COMPLETION_CODE;
      }

      if ( this._needBinding ) {
        // Do resource binding:
        // Tell the server to generate the resource ID for us.
        this._stepNumber = 3;
        return "<iq type='set' id='bind_1'><bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'/></iq>";
      }

      this._errorMsg = "Server requested session not binding: can't happen?";
      return false;
    } else if ( this._stepNumber == 3 ) {
      // Pull the JID out of the stuff the server sends us.
      var jidNodes = rootElem.getElementsByTagName( "jid" );
      if ( jidNodes.length == 0 ) {
	      this._errorMsg = "Expected JID node from server, got none.";
	      return false;
      }
      this._jid = jidNodes[0].firstChild.nodeValue;
      // TODO: Does the client need to do anything special with its new
      // "client@host.com/resourceID"  full JID?

      // If we still need to do session, then we're not done yet:
      if ( this._needSession ) {
	      this._stepNumber = 4;
	      return "<iq to='" + this._realm + "' type='set' id='sess_1'><session xmlns='urn:ietf:params:xml:ns:xmpp-session'/></iq>";
      } else {
	      return this.COMPLETION_CODE;
      }
    } else if ( this._stepNumber == 4 ) {
      // OK, now we're done.
      return this.COMPLETION_CODE;
    }
  }

};
PlainAuthenticator.prototype.__proto__ = new BaseAuthenticator();