public boolean authenticate(HttpRequest request,
    HttpResponse response,
    LoginConfig config) throws IOException 
{
      HttpServletRequest hreq =
            (HttpServletRequest) request.getRequest();
      // Have we already authenticated someone?
      // Note: SingleSignOn does not call setUserPrincipal(),
      // so whoever did it would have to be some custom valve
      // in the pipeline
      Principal principal = hreq.getUserPrincipal();
      String ssoId = (String) request.getNote(Constants.REQ_SSOID_NOTE);
      if (principal != null)
      {
         if (debug  >= 1)
            log("Found principal '" + principal.getName() + "'");
         // Associate the session with any existing SSO session
         if (ssoId != null)
            associate(ssoId, getSession(request, true));
         return true;
      }
      // Is there an SSO session against which we can try to reauthenticate?
      if (ssoId != null)
      {
         if (debug  >= 1)
            log("SSO Id set");
         // Try to reauthenticate using data cached by SSO.  If this fails,
         // either the original SSO logon was of DIGEST or SSL (which
         // we can't reauthenticate ourselves because there is no
         // cached username and password), or the realm denied
         // the user's reauthentication for some reason.
         // In either case we have to prompt the user for a logon */
         if (reauthenticateFromSSO(ssoId, request))
            return true;
      }
      // Validate any credentials already included with this request
      String authorization = request.getAuthorization();
      String username = parseUsername(authorization);
      String password = parsePassword(authorization);
      principal = context.getRealm().authenticate(username, password);
      if (principal != null)
      {
         register(request, response, principal, Constants.BASIC_METHOD,
                  username, password);
         return (true);
      }
      // Send an "unauthorized" response and an appropriate challenge
      String realmName = config.getRealmName();
      if (realmName == null)
         realmName = hreq.getServerName() + ":" + hreq.getServerPort();
      //        if (debug  >= 1)
      //            log("Challenging for realm '" + realmName + "'");
      HttpServletResponse hres =
            (HttpServletResponse) response.getResponse();
      hres.setHeader("WWW-Authenticate",
                     "Basic realm=\"" + realmName + "\"");
      hres.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
      //      hres.flushBuffer();
      return (false);
}

Authenticate the user making this request, based on the specified login configuration. Return true if any specified constraint has been satisfied, or false if we have created a response challenge already.

Differs from the standard Tomcat version in that it associates the session of any request with any single sign-on session that may exist.

 public String getInfo() 
{
   // ------------------------------------------------------------- Properties
      return (this.info);
}

Return descriptive information about this Valve implementation.

 protected String parsePassword(String authorization) 
{
      if (authorization == null)
         return (null);
      if (!authorization.startsWith("Basic "))
         return (null);
      authorization = authorization.substring(6).trim();
      // Decode and parse the authorization credentials
      String unencoded =
            new String(base64Helper.decode(authorization.getBytes()));
      int colon = unencoded.indexOf(':");
      if (colon <  0)
         return (null);
      //        String username = unencoded.substring(0, colon).trim();
      String password = unencoded.substring(colon + 1).trim();
      return (password);
}

Parse the password from the specified authorization credentials. If none can be found, return null.

 protected String parseUsername(String authorization) 
{
      if (authorization == null)
         return (null);
      if (!authorization.toLowerCase().startsWith("basic "))
         return (null);
      authorization = authorization.substring(6).trim();
      // Decode and parse the authorization credentials
      String unencoded =
            new String(base64Helper.decode(authorization.getBytes()));
      int colon = unencoded.indexOf(':");
      if (colon <  0)
         return (null);
      String username = unencoded.substring(0, colon).trim();
      //        String password = unencoded.substring(colon + 1).trim();
      return (username);
}

Parse the username from the specified authorization credentials. If none can be found, return null.