org.springframework.security.access.expression.method.MethodSecurityEvaluationContext.java Source code

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Here is the source code for org.springframework.security.access.expression.method.MethodSecurityEvaluationContext.java

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/*
 * Copyright 2002-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.security.access.expression.method;

import java.lang.reflect.Method;

import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.aop.framework.AopProxyUtils;
import org.springframework.aop.support.AopUtils;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.parameters.DefaultSecurityParameterNameDiscoverer;

/**
 * Internal security-specific EvaluationContext implementation which lazily adds the
 * method parameter values as variables (with the corresponding parameter names) if and
 * when they are required.
 *
 * @author Luke Taylor
 * @since 3.0
 */
class MethodSecurityEvaluationContext extends StandardEvaluationContext {
    private static final Log logger = LogFactory.getLog(MethodSecurityEvaluationContext.class);

    private ParameterNameDiscoverer parameterNameDiscoverer;
    private final MethodInvocation mi;
    private boolean argumentsAdded;

    /**
     * Intended for testing. Don't use in practice as it creates a new parameter resolver
     * for each instance. Use the constructor which takes the resolver, as an argument
     * thus allowing for caching.
     */
    public MethodSecurityEvaluationContext(Authentication user, MethodInvocation mi) {
        this(user, mi, new DefaultSecurityParameterNameDiscoverer());
    }

    public MethodSecurityEvaluationContext(Authentication user, MethodInvocation mi,
            ParameterNameDiscoverer parameterNameDiscoverer) {
        this.mi = mi;
        this.parameterNameDiscoverer = parameterNameDiscoverer;
    }

    @Override
    public Object lookupVariable(String name) {
        Object variable = super.lookupVariable(name);

        if (variable != null) {
            return variable;
        }

        if (!argumentsAdded) {
            addArgumentsAsVariables();
            argumentsAdded = true;
        }

        variable = super.lookupVariable(name);

        if (variable != null) {
            return variable;
        }

        return null;
    }

    public void setParameterNameDiscoverer(ParameterNameDiscoverer parameterNameDiscoverer) {
        this.parameterNameDiscoverer = parameterNameDiscoverer;
    }

    private void addArgumentsAsVariables() {
        Object[] args = mi.getArguments();

        if (args.length == 0) {
            return;
        }

        Object targetObject = mi.getThis();
        // SEC-1454
        Class<?> targetClass = AopProxyUtils.ultimateTargetClass(targetObject);

        if (targetClass == null) {
            // TODO: Spring should do this, but there's a bug in ultimateTargetClass()
            // which returns null
            targetClass = targetObject.getClass();
        }

        Method method = AopUtils.getMostSpecificMethod(mi.getMethod(), targetClass);
        String[] paramNames = parameterNameDiscoverer.getParameterNames(method);

        if (paramNames == null) {
            logger.warn("Unable to resolve method parameter names for method: " + method
                    + ". Debug symbol information is required if you are using parameter names in expressions.");
            return;
        }

        for (int i = 0; i < args.length; i++) {
            if (paramNames[i] != null) {
                setVariable(paramNames[i], args[i]);
            }
        }
    }

}