Cross-Origin Resource Sharing with Spring Security

by

I was able to do this by extending UsernamePasswordAuthenticationFilter… my code is in Groovy, hope that’s OK:

public class CorsAwareAuthenticationFilter extends UsernamePasswordAuthenticationFilter {
    static final String ORIGIN = 'Origin'

    @Override
    public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response){
        if (request.getHeader(ORIGIN)) {
            String origin = request.getHeader(ORIGIN)
            response.addHeader('Access-Control-Allow-Origin', origin)
            response.addHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE')
            response.addHeader('Access-Control-Allow-Credentials', 'true')
            response.addHeader('Access-Control-Allow-Headers',
                    request.getHeader('Access-Control-Request-Headers'))
        }
        if (request.method == 'OPTIONS') {
            response.writer.print('OK')
            response.writer.flush()
            return
        }
        return super.attemptAuthentication(request, response)
    }
}

The important bits above:

  • Only add CORS headers to response if CORS request detected
  • Respond to pre-flight OPTIONS request with a simple non-empty 200 response, which also contains the CORS headers.

You need to declare this bean in your Spring configuration. There are many articles showing how to do this so I won’t copy that here.

In my own implementation I use an origin domain whitelist as I am allowing CORS for internal developer access only. The above is a simplified version of what I am doing so may need tweaking but this should give you the general idea.

Leave a Comment

tech