- All Implemented Interfaces:
public class AddDefaultCharsetFilter extends FilterBaseFilter that explicitly sets the default character set for media subtypes of the "text" type to ISO-8859-1, or another user defined character set. RFC2616 explicitly states that browsers must use ISO-8859-1 if no character set is defined for media with subtype "text". However, browsers may attempt to auto-detect the character set. This may be exploited by an attacker to perform an XSS attack. Internet Explorer has this behaviour by default. Other browsers have an option to enable it.
This filter prevents the attack by explicitly setting a character set. Unless the provided character set is explicitly overridden by the user - in which case they deserve everything they get - the browser will adhere to an explicitly set character set, thus preventing the XSS attack.
Nested Class Summary
Nested Classes Modifier and Type Class Description
AddDefaultCharsetFilter.ResponseWrapperWrapper that adds a character set for text media types if no character set is specified.
Fields inherited from class org.apache.catalina.filters.FilterBase
Constructors Constructor Description
All Methods Instance Methods Concrete Methods Modifier and Type Method Description
doFilter(ServletRequest request, ServletResponse response, FilterChain chain)The
doFiltermethod of the Filter is called by the container each time a request/response pair is passed through the chain due to a client request for a resource at the end of the chain.
init(FilterConfig filterConfig)Iterates over the configuration parameters and either logs a warning, or throws an exception for any parameter that does not have a matching setter in this filter.
Methods inherited from class org.apache.catalina.filters.FilterBase
public void setEncoding(java.lang.String encoding)
protected Log getLogger()
- Specified by:
public void init(FilterConfig filterConfig) throws ServletExceptionDescription copied from class:
FilterBaseIterates over the configuration parameters and either logs a warning, or throws an exception for any parameter that does not have a matching setter in this filter.
- Specified by:
filterConfig- The configuration information associated with the filter instance being initialised
trueand a configured parameter does not have a matching setter
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws java.io.IOException, ServletExceptionDescription copied from interface:
doFiltermethod of the Filter is called by the container each time a request/response pair is passed through the chain due to a client request for a resource at the end of the chain. The FilterChain passed in to this method allows the Filter to pass on the request and response to the next entity in the chain.
A typical implementation of this method would follow the following pattern:-
1. Examine the request
2. Optionally wrap the request object with a custom implementation to filter content or headers for input filtering
3. Optionally wrap the response object with a custom implementation to filter content or headers for output filtering
4. a) Either invoke the next entity in the chain using the FilterChain object (
4. b) or not pass on the request/response pair to the next entity in the filter chain to block the request processing
5. Directly set headers on the response after invocation of the next entity in the filter chain.
request- The request to process
response- The response associated with the request
chain- Provides access to the next filter in the chain for this filter to pass the request and response to for further processing
java.io.IOException- if an I/O error occurs during this filter's processing of the request
ServletException- if the processing fails for any other reason