private void parse() throws ParsingException {
    skipSpaces();
    if (buffer[index] != '(')
      throw new ParsingException("error in FETCH parsing, missing '(' at index " + index);

    List<Item> v = new ArrayList<Item>();
    Item i = null;
    do {
      index++; // skip '(', or SPACE

      if (index >= size)
        throw new ParsingException("error in FETCH parsing, ran off end of buffer, size " + size);

      i = parseItem();
      if (i != null) v.add(i);
      else if (!parseExtensionItem())
        throw new ParsingException(
            "error in FETCH parsing, unrecognized item at index "
                + index
                + ", starts with \""
                + next20()
                + "\"");
    } while (buffer[index] != ')');

    index++; // skip ')'
    items = v.toArray(new Item[v.size()]);
  }
  /**
   * Return all fetch response items of the given class for the given message number.
   *
   * @param r the responses
   * @param msgno the message number
   * @param c the class
   * @param	<T> the type of fetch items
   * @return the list of fetch items
   * @since JavaMail 1.5.2
   */
  public static <T extends Item> List<T> getItems(Response[] r, int msgno, Class<T> c) {
    List<T> items = new ArrayList<T>();

    if (r == null) return items;

    for (int i = 0; i < r.length; i++) {

      if (r[i] == null
          || !(r[i] instanceof FetchResponse)
          || ((FetchResponse) r[i]).getNumber() != msgno) continue;

      FetchResponse f = (FetchResponse) r[i];
      for (int j = 0; j < f.items.length; j++) {
        if (c.isInstance(f.items[j])) items.add(c.cast(f.items[j]));
      }
    }

    return items;
  }
  /**
   * Read a list of space-separated "flag_extension" sequences and return the list as a array of
   * Strings. An empty list is returned as null. This is an IMAP-ism, and perhaps this method should
   * moved into the IMAP layer.
   */
  public String[] readSimpleList() {
    skipSpaces();

    if (buffer[index] != '(') // not what we expected
    return null;
    index++; // skip '('

    List<String> v = new ArrayList<String>();
    int start;
    for (start = index; buffer[index] != ')'; index++) {
      if (buffer[index] == ' ') { // got one item
        v.add(ASCIIUtility.toString(buffer, start, index));
        start = index + 1; // index gets incremented at the top
      }
    }
    if (index > start) // get the last item
    v.add(ASCIIUtility.toString(buffer, start, index));
    index++; // skip ')'

    int size = v.size();
    if (size > 0) return v.toArray(new String[size]);
    else // empty list
    return null;
  }
  public boolean authenticate(
      String[] mechs, final String realm, final String authzid, final String u, final String p)
      throws ProtocolException {

    synchronized (pr) { // authenticate method should be synchronized
      List<Response> v = new ArrayList<Response>();
      String tag = null;
      Response r = null;
      boolean done = false;
      if (logger.isLoggable(Level.FINE)) {
        logger.fine("SASL Mechanisms:");
        for (int i = 0; i < mechs.length; i++) logger.fine(" " + mechs[i]);
        logger.fine("");
      }

      SaslClient sc;
      CallbackHandler cbh =
          new CallbackHandler() {
            public void handle(Callback[] callbacks) {
              if (logger.isLoggable(Level.FINE))
                logger.fine("SASL callback length: " + callbacks.length);
              for (int i = 0; i < callbacks.length; i++) {
                if (logger.isLoggable(Level.FINE))
                  logger.fine("SASL callback " + i + ": " + callbacks[i]);
                if (callbacks[i] instanceof NameCallback) {
                  NameCallback ncb = (NameCallback) callbacks[i];
                  ncb.setName(u);
                } else if (callbacks[i] instanceof PasswordCallback) {
                  PasswordCallback pcb = (PasswordCallback) callbacks[i];
                  pcb.setPassword(p.toCharArray());
                } else if (callbacks[i] instanceof RealmCallback) {
                  RealmCallback rcb = (RealmCallback) callbacks[i];
                  rcb.setText(realm != null ? realm : rcb.getDefaultText());
                } else if (callbacks[i] instanceof RealmChoiceCallback) {
                  RealmChoiceCallback rcb = (RealmChoiceCallback) callbacks[i];
                  if (realm == null) rcb.setSelectedIndex(rcb.getDefaultChoice());
                  else {
                    // need to find specified realm in list
                    String[] choices = rcb.getChoices();
                    for (int k = 0; k < choices.length; k++) {
                      if (choices[k].equals(realm)) {
                        rcb.setSelectedIndex(k);
                        break;
                      }
                    }
                  }
                }
              }
            }
          };

      try {
        sc = Sasl.createSaslClient(mechs, authzid, name, host, (Map) props, cbh);
      } catch (SaslException sex) {
        logger.log(Level.FINE, "Failed to create SASL client", sex);
        throw new UnsupportedOperationException(sex.getMessage(), sex);
      }
      if (sc == null) {
        logger.fine("No SASL support");
        throw new UnsupportedOperationException("No SASL support");
      }
      if (logger.isLoggable(Level.FINE)) logger.fine("SASL client " + sc.getMechanismName());

      try {
        Argument args = new Argument();
        args.writeAtom(sc.getMechanismName());
        if (pr.hasCapability("SASL-IR") && sc.hasInitialResponse()) {
          String irs;
          byte[] ba = sc.evaluateChallenge(new byte[0]);
          if (ba.length > 0) {
            ba = BASE64EncoderStream.encode(ba);
            irs = ASCIIUtility.toString(ba, 0, ba.length);
          } else irs = "=";
          args.writeAtom(irs);
        }
        tag = pr.writeCommand("AUTHENTICATE", args);
      } catch (Exception ex) {
        logger.log(Level.FINE, "SASL AUTHENTICATE Exception", ex);
        return false;
      }

      OutputStream os = pr.getIMAPOutputStream(); // stream to IMAP server

      /*
       * Wrap a BASE64Encoder around a ByteArrayOutputstream
       * to craft b64 encoded username and password strings
       *
       * Note that the encoded bytes should be sent "as-is" to the
       * server, *not* as literals or quoted-strings.
       *
       * Also note that unlike the B64 definition in MIME, CRLFs
       * should *not* be inserted during the encoding process. So, I
       * use Integer.MAX_VALUE (0x7fffffff (> 1G)) as the bytesPerLine,
       * which should be sufficiently large !
       */

      ByteArrayOutputStream bos = new ByteArrayOutputStream();
      byte[] CRLF = {(byte) '\r', (byte) '\n'};

      // Hack for Novell GroupWise XGWTRUSTEDAPP authentication mechanism
      // http://www.novell.com/developer/documentation/gwimap/?
      //   page=/developer/documentation/gwimap/gwimpenu/data/al7te9j.html
      boolean isXGWTRUSTEDAPP =
          sc.getMechanismName().equals("XGWTRUSTEDAPP")
              && PropUtil.getBooleanProperty(
                  props, "mail." + name + ".sasl.xgwtrustedapphack.enable", true);
      while (!done) { // loop till we are done
        try {
          r = pr.readResponse();
          if (r.isContinuation()) {
            byte[] ba = null;
            if (!sc.isComplete()) {
              ba = r.readByteArray().getNewBytes();
              if (ba.length > 0) ba = BASE64DecoderStream.decode(ba);
              if (logger.isLoggable(Level.FINE))
                logger.fine("SASL challenge: " + ASCIIUtility.toString(ba, 0, ba.length) + " :");
              ba = sc.evaluateChallenge(ba);
            }
            if (ba == null) {
              logger.fine("SASL no response");
              os.write(CRLF); // write out empty line
              os.flush(); // flush the stream
              bos.reset(); // reset buffer
            } else {
              if (logger.isLoggable(Level.FINE))
                logger.fine("SASL response: " + ASCIIUtility.toString(ba, 0, ba.length) + " :");
              ba = BASE64EncoderStream.encode(ba);
              if (isXGWTRUSTEDAPP) bos.write(ASCIIUtility.getBytes("XGWTRUSTEDAPP "));
              bos.write(ba);

              bos.write(CRLF); // CRLF termination
              os.write(bos.toByteArray()); // write out line
              os.flush(); // flush the stream
              bos.reset(); // reset buffer
            }
          } else if (r.isTagged() && r.getTag().equals(tag))
            // Ah, our tagged response
            done = true;
          else if (r.isBYE()) // outta here
          done = true;
          else // hmm .. unsolicited response here ?!
          v.add(r);
        } catch (Exception ioex) {
          logger.log(Level.FINE, "SASL Exception", ioex);
          // convert this into a BYE response
          r = Response.byeResponse(ioex);
          done = true;
          // XXX - ultimately return true???
        }
      }

      if (sc.isComplete() /*&& res.status == SUCCESS*/) {
        String qop = (String) sc.getNegotiatedProperty(Sasl.QOP);
        if (qop != null
            && (qop.equalsIgnoreCase("auth-int") || qop.equalsIgnoreCase("auth-conf"))) {
          // XXX - NOT SUPPORTED!!!
          logger.fine("SASL Mechanism requires integrity or confidentiality");
          return false;
        }
      }

      /* Dispatch untagged responses.
       * NOTE: in our current upper level IMAP classes, we add the
       * responseHandler to the Protocol object only *after* the
       * connection has been authenticated. So, for now, the below
       * code really ends up being just a no-op.
       */
      Response[] responses = v.toArray(new Response[v.size()]);
      pr.notifyResponseHandlers(responses);

      // Handle the final OK, NO, BAD or BYE response
      pr.handleResult(r);
      pr.setCapabilities(r);

      /*
       * If we're using the Novell Groupwise XGWTRUSTEDAPP mechanism
       * to run as a specified authorization ID, we have to issue a
       * LOGIN command to select the user we want to operate as.
       */
      if (isXGWTRUSTEDAPP && authzid != null) {
        Argument args = new Argument();
        args.writeString(authzid);

        responses = pr.command("LOGIN", args);

        // dispatch untagged responses
        pr.notifyResponseHandlers(responses);

        // Handle result of this command
        pr.handleResult(responses[responses.length - 1]);
        // If the response includes a CAPABILITY response code, process it
        pr.setCapabilities(responses[responses.length - 1]);
      }
      return true;
    }
  }