Return HTTP Error 401 Code & Skip Filter Chains

Question

Using a custom Spring Security filter, I'd like to return an HTTP 401 error code if the HTTP Header doesn't contain a particular key-value pair.

Example:

public void doFilter(ServletRequest req, ServletResponse res,                      FilterChain chain) throws IOException, ServletException {     HttpServletRequest request = (HttpServletRequest) req;    final String val = request.getHeader(FOO_TOKEN)     if(val == null || !val.equals("FOO")) {        // token is not valid, return an HTTP 401 error code        ...    }    else {     // token is good, let it proceed     chain.doFilter(req, res);    } 

As I understand, I could do the following:

(1) ((HttpServletResponse) res).setStatus(401) and skip the remaining filter chain

OR

(2) throw an exception that, eventually, results in Spring Security throwing a 401 error to the client.

If #1 is the better option, how can I skip the filter chain after calling setStatus(401) on the response?

Or, if #2 is the right way to go, which exception should I throw?

Answer 1

I suggest this solution below.

public void doFilter(ServletRequest req, ServletResponse res,                          FilterChain chain) throws IOException, ServletException {          HttpServletRequest request = (HttpServletRequest) req;         final String val = request.getHeader(FOO_TOKEN)          if (val == null || !val.equals("FOO")) {             ((HttpServletResponse) response).sendError(HttpServletResponse.SC_UNAUTHORIZED, "The token is not valid.");         } else {             chain.doFilter(req, res);         }     } 

Answer 2

From the API docs for the doFilter method, you can:

• Either invoke the next entity in the chain using the FilterChain object (chain.doFilter()),
• or not pass on the request/response pair to the next entity in the filter chain to block the request processing

so setting the response status code and returning immediately without invoking chain.doFilter is the best option for what you want to achieve here.