public User authenticate()

in core/src/main/java/org/apache/ftpserver/usermanager/impl/DbUserManager.java [607:679]
65 lines of code
12 McCabe index (conditional complexity)

    public User authenticate(Authentication authentication)
            throws AuthenticationFailedException {
        if (authentication instanceof UsernamePasswordAuthentication) {
            UsernamePasswordAuthentication upauth = (UsernamePasswordAuthentication) authentication;

            String user = upauth.getUsername();
            String password = upauth.getPassword();

            if (user == null) {
                throw new AuthenticationFailedException("Authentication failed");
            }

            if (password == null) {
                password = "";
            }

            Statement stmt = null;
            ResultSet rs = null;
            try {

                // create the sql query
                HashMap<String, Object> map = new HashMap<>();
                map.put(ATTR_LOGIN, escapeString(user));
                String sql = StringUtils.replaceString(authenticateStmt, map);
                LOG.info(sql);

                // execute query
                stmt = createConnection().createStatement();
                rs = stmt.executeQuery(sql);
                if (rs.next()) {
                    try {
                        String storedPassword = rs.getString(ATTR_PASSWORD);
                        if (getPasswordEncryptor().matches(password, storedPassword)) {
                            return getUserByName(user);
                        } else {
                            throw new AuthenticationFailedException(
                                    "Authentication failed");
                        }
                    } catch (FtpException e) {
                        throw new AuthenticationFailedException(
                                "Authentication failed", e);
                    }
                } else {
                    throw new AuthenticationFailedException(
                            "Authentication failed");
                }
            } catch (SQLException ex) {
                LOG.error("DbUserManager.authenticate()", ex);
                throw new AuthenticationFailedException(
                        "Authentication failed", ex);
            } finally {
                closeQuitely(rs);
                closeQuitely(stmt);
            }
        } else if (authentication instanceof AnonymousAuthentication) {
            try {
                if (doesExist("anonymous")) {
                    return getUserByName("anonymous");
                } else {
                    throw new AuthenticationFailedException(
                            "Authentication failed");
                }
            } catch (AuthenticationFailedException e) {
                throw e;
            } catch (FtpException e) {
                throw new AuthenticationFailedException(
                        "Authentication failed", e);
            }
        } else {
            throw new IllegalArgumentException(
                    "Authentication not supported by this user manager");
        }
    }