Redirect from JWT Authendication Filter on Spring Security - spring

Question

I am using jwt authentication with spring:boot on my application. Everything is fine. If a valid token is there in the header it is getting validated and the response is sending fine.
But how to redirect invalid requests to login page and after successful login redirect them back to their initial requested page.
Here is my config method
httpSecurity
.csrf().disable().exceptionHandling().authenticationEntryPoint(unauthorizedHandler).and()
.sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS).and()
.authorizeRequests()
.antMatchers(HttpMethod.GET, "/", "/*.html", "/favicon.ico", "/**/*.html", "/**/*.css", "/**/*.js")
.permitAll().antMatchers("/auth/**").permitAll().anyRequest().authenticated();
httpSecurity.addFilterBefore(authenticationTokenFilterBean(), UsernamePasswordAuthenticationFilter.class);
httpSecurity.headers().cacheControl();
Here is my authendication filter
#Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
ServletException {
HttpServletRequest httpRequest = (HttpServletRequest) request;
String authToken = httpRequest.getHeader(this.tokenHeader);
// authToken.startsWith("Bearer ")
// String authToken = header.substring(7);
String username = jwtTokenUtil.getUsernameFromToken(authToken);
System.out.println("Token is " + authToken);
System.out.println("Username is " + username);
System.out.println("Audience is from " + jwtTokenUtil.getAudienceFromToken(authToken));
if (username != null && SecurityContextHolder.getContext().getAuthentication() == null) {
UserDetails userDetails = this.userDetailsService.loadUserByUsername(username);
System.out.println(userDetails.getAuthorities());
if (jwtTokenUtil.validateToken(authToken, userDetails)) {
UsernamePasswordAuthenticationToken authentication = new UsernamePasswordAuthenticationToken(
userDetails, null, userDetails.getAuthorities());
authentication.setDetails(new WebAuthenticationDetailsSource().buildDetails(httpRequest));
SecurityContextHolder.getContext().setAuthentication(authentication);
} else {
System.out.println("Token is invalid ");
}
}
chain.doFilter(request, response);
}
}

Answer 1

The purpose of using JWT / Stateless security is to not keep any client data on the backend that would require request to go back to that node for it to function properly, thus allowing any request to go to any backend instance. This increases scalability in the application, while also making it more difficult to do what you just described.
Because the front end is now where your user state is stored, JS or some other front end technology will need to be responsible for implementing this behavior. Using a framework has a higher learning curve then vanilla JS, but it will be much easier in the long run to manage and implement complex requirements.