com.opensymphony.xwork2.interceptor
Class ParametersInterceptor

java.lang.Object
  extended by com.opensymphony.xwork2.interceptor.AbstractInterceptor
      extended by com.opensymphony.xwork2.interceptor.MethodFilterInterceptor
          extended by com.opensymphony.xwork2.interceptor.ParametersInterceptor
All Implemented Interfaces:
Interceptor, Serializable

public class ParametersInterceptor
extends MethodFilterInterceptor

This interceptor sets all parameters on the value stack. This interceptor gets all parameters from ActionContext.getParameters() and sets them on the value stack by calling ValueStack.setValue(String, Object), typically resulting in the values submitted in a form request being applied to an action in the value stack. Note that the parameter map must contain a String key and often containers a String[] for the value. The interceptor takes one parameter named 'ordered'. When set to true action properties are guaranteed to be set top-down which means that top action's properties are set first. Then it's subcomponents properties are set. The reason for this order is to enable a 'factory' pattern. For example, let's assume that one has an action that contains a property named 'modelClass' that allows to choose what is the underlying implementation of model. By assuring that modelClass property is set before any model properties are set, it's possible to choose model implementation during action.setModelClass() call. Similiarily it's possible to use action.setPrimaryKey() property set call to actually load the model class from persistent storage. Without any assumption on parameter order you have to use patterns like 'Preparable'. Because parameter names are effectively OGNL statements, it is important that security be taken in to account. This interceptor will not apply any values in the parameters map if the expression contains an assignment (=), multiple expressions (,), or references any objects in the context (#). This is all done in the acceptableName(String) method. In addition to this method, if the action being invoked implements the ParameterNameAware interface, the action will be consulted to determine if the parameter should be set. In addition to these restrictions, a flag (ReflectionContextState.DENY_METHOD_EXECUTION) is set such that no methods are allowed to be invoked. That means that any expression such as person.doSomething() or person.getName() will be explicitely forbidden. This is needed to make sure that your application is not exposed to attacks by malicious users. While this interceptor is being invoked, a flag (ReflectionContextState.CREATE_NULL_OBJECTS) is turned on to ensure that any null reference is automatically created - if possible. See the type conversion documentation and the InstantiatingNullHandler javadocs for more information. Finally, a third flag (XWorkConverter.REPORT_CONVERSION_ERRORS) is set that indicates any errors when converting the the values to their final data type (String[] -> int) an unrecoverable error occured. With this flag set, the type conversion errors will be reported in the action context. See the type conversion documentation and the XWorkConverter javadocs for more information. If you are looking for detailed logging information about your parameters, turn on DEBUG level logging for this interceptor. A detailed log of all the parameter keys and values will be reported. Note: Since XWork 2.0.2, this interceptor extends MethodFilterInterceptor, therefore being able to deal with excludeMethods / includeMethods parameters. See [Workflow Interceptor] (class DefaultWorkflowInterceptor) for documentation and examples on how to use this feature. Interceptor parameters:

Extending the interceptor: The best way to add behavior to this interceptor is to utilize the ParameterNameAware interface in your actions. However, if you wish to apply a global rule that isn't implemented in your action, then you could extend this interceptor and override the acceptableName(String) method. Using ParameterNameAware could be dangerous as ParameterNameAware.acceptableParameterName(String) takes precedence over ParametersInterceptor which means if ParametersInterceptor excluded given parameter name you can accept it with ParameterNameAware.acceptableParameterName(String). The best idea is to define very tight restrictions with ParametersInterceptor and relax them per action with ParameterNameAware.acceptableParameterName(String) Example code:
 
 <action name="someAction" class="com.examples.SomeAction">
     <interceptor-ref name="params"/>
     <result name="success">good_result.ftl</result>
 </action>
 
 

Author:
Patrick Lightbody
See Also:
Serialized Form

Field Summary
protected  boolean ordered
           
protected static int PARAM_NAME_MAX_LENGTH
           
 
Fields inherited from class com.opensymphony.xwork2.interceptor.MethodFilterInterceptor
excludeMethods, includeMethods, log
 
Constructor Summary
ParametersInterceptor()
           
 
Method Summary
protected  boolean acceptableName(String name)
           
protected  void addParametersToContext(ActionContext ac, Map<String,Object> newParams)
          Adds the parameters into context's ParameterMap
 String doIntercept(ActionInvocation invocation)
          Subclasses must override to implement the interceptor logic.
protected  Comparator<String> getOrderedComparator()
          Gets an instance of the comparator to use for the ordered sorting.
protected  String getParameterLogMap(Map<String,Object> parameters)
           
protected  boolean isAcceptableParameter(String name, Object action)
          Checks if name of parameter can be accepted or thrown away
protected  boolean isAcceptableValue(Object value)
          Checks if given value doesn't match global excluded patterns to avoid passing malicious code
protected  boolean isAccepted(String paramName)
           
protected  boolean isExcluded(String paramName)
           
 boolean isOrdered()
          Whether to order the parameters or not
protected  boolean isWithinLengthLimit(String name)
           
protected  void notifyDeveloperParameterException(Object action, String property, String message)
           
protected  Map<String,Object> retrieveParameters(ActionContext ac)
          Gets the parameter map to apply from wherever appropriate
 void setAcceptedPatterns(AcceptedPatternsChecker acceptedPatterns)
           
 void setAcceptParamNames(String commaDelim)
          Sets a comma-delimited list of regular expressions to match parameters that are allowed in the parameter map (aka whitelist).
 void setDevMode(String mode)
           
 void setExcludedPatterns(ExcludedPatternsChecker excludedPatterns)
           
 void setExcludeParams(String commaDelim)
          Sets a comma-delimited list of regular expressions to match parameters that should be removed from the parameter map.
 void setOrdered(boolean ordered)
          Set whether to order the parameters by object depth or not
protected  void setParameters(Object action, ValueStack stack, Map<String,Object> parameters)
           
 void setParamNameMaxLength(int paramNameMaxLength)
          If the param name exceeds the configured maximum length it will not be accepted.
 void setValueStackFactory(ValueStackFactory valueStackFactory)
           
 
Methods inherited from class com.opensymphony.xwork2.interceptor.MethodFilterInterceptor
applyInterceptor, getExcludeMethodsSet, getIncludeMethodsSet, intercept, setExcludeMethods, setIncludeMethods
 
Methods inherited from class com.opensymphony.xwork2.interceptor.AbstractInterceptor
destroy, init
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

PARAM_NAME_MAX_LENGTH

protected static final int PARAM_NAME_MAX_LENGTH
See Also:
Constant Field Values

ordered

protected boolean ordered
Constructor Detail

ParametersInterceptor

public ParametersInterceptor()
Method Detail

setValueStackFactory

public void setValueStackFactory(ValueStackFactory valueStackFactory)

setDevMode

public void setDevMode(String mode)

setExcludedPatterns

public void setExcludedPatterns(ExcludedPatternsChecker excludedPatterns)

setAcceptedPatterns

public void setAcceptedPatterns(AcceptedPatternsChecker acceptedPatterns)

setParamNameMaxLength

public void setParamNameMaxLength(int paramNameMaxLength)
If the param name exceeds the configured maximum length it will not be accepted.

Parameters:
paramNameMaxLength - Maximum length of param names

doIntercept

public String doIntercept(ActionInvocation invocation)
                   throws Exception
Description copied from class: MethodFilterInterceptor
Subclasses must override to implement the interceptor logic.

Specified by:
doIntercept in class MethodFilterInterceptor
Parameters:
invocation - the action invocation
Returns:
the result of invocation
Throws:
Exception

retrieveParameters

protected Map<String,Object> retrieveParameters(ActionContext ac)
Gets the parameter map to apply from wherever appropriate

Parameters:
ac - The action context
Returns:
The parameter map to apply

addParametersToContext

protected void addParametersToContext(ActionContext ac,
                                      Map<String,Object> newParams)
Adds the parameters into context's ParameterMap

Parameters:
ac - The action context
newParams - The parameter map to apply

In this class this is a no-op, since the parameters were fetched from the same location. In subclasses both retrieveParameters() and addParametersToContext() should be overridden.


setParameters

protected void setParameters(Object action,
                             ValueStack stack,
                             Map<String,Object> parameters)

notifyDeveloperParameterException

protected void notifyDeveloperParameterException(Object action,
                                                 String property,
                                                 String message)

isAcceptableParameter

protected boolean isAcceptableParameter(String name,
                                        Object action)
Checks if name of parameter can be accepted or thrown away

Parameters:
name - parameter name
action - current action
Returns:
true if parameter is accepted

isAcceptableValue

protected boolean isAcceptableValue(Object value)
Checks if given value doesn't match global excluded patterns to avoid passing malicious code

Parameters:
value - incoming parameter's value
Returns:
true if value is safe FIXME: can be removed when parameters won't be represented as simple Strings

getOrderedComparator

protected Comparator<String> getOrderedComparator()
Gets an instance of the comparator to use for the ordered sorting. Override this method to customize the ordering of the parameters as they are set to the action.

Returns:
A comparator to sort the parameters

getParameterLogMap

protected String getParameterLogMap(Map<String,Object> parameters)

acceptableName

protected boolean acceptableName(String name)

isWithinLengthLimit

protected boolean isWithinLengthLimit(String name)

isAccepted

protected boolean isAccepted(String paramName)

isExcluded

protected boolean isExcluded(String paramName)

isOrdered

public boolean isOrdered()
Whether to order the parameters or not

Returns:
True to order

setOrdered

public void setOrdered(boolean ordered)
Set whether to order the parameters by object depth or not

Parameters:
ordered - True to order them

setAcceptParamNames

public void setAcceptParamNames(String commaDelim)
Sets a comma-delimited list of regular expressions to match parameters that are allowed in the parameter map (aka whitelist).

Don't change the default unless you know what you are doing in terms of security implications.

Parameters:
commaDelim - A comma-delimited list of regular expressions

setExcludeParams

public void setExcludeParams(String commaDelim)
Sets a comma-delimited list of regular expressions to match parameters that should be removed from the parameter map.

Parameters:
commaDelim - A comma-delimited list of regular expressions


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