return null;
                }
                /* negotiation complete, remove the challenge object */
                ssn.removeAttribute("NtlmHttpChal");
            }
            else {
                String auth = new String(Base64.decode(msg.substring(6)), "US-ASCII");
                int index = auth.indexOf(':');

                    return null;
                }
                /* negotiation complete, remove the challenge object */
                ssn.removeAttribute( "NtlmHttpChal" );
            } else {
                String auth = new String(Base64.decode(msg.substring(6)),
                        "US-ASCII");
                int index = auth.indexOf(':');

            }
            else {
                doFile(req, resp, file);
            }
        }
        catch ( SmbAuthException sae ) {
            if ( ssn != null ) {
                ssn.removeAttribute("npa-" + server);
            }
            if ( sae.getNtStatus() == NtStatus.NT_STATUS_ACCESS_VIOLATION ) {
                /*
                 * Server challenge no longer valid for

            } else {
                doFile( req, resp, file );
            }
        } catch( SmbAuthException sae ) {
            if( ssn != null ) {
                ssn.removeAttribute( "npa-" + server );
            }
            if( sae.getNtStatus() == sae.NT_STATUS_ACCESS_VIOLATION ) {
                /* Server challenge no longer valid for
                 * externally supplied password hashes.