RequestParameterAspect.java

/*
 * Copyright 2011-2016 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
 *
 * http://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.glowroot.agent.plugin.servlet;

import java.util.Map;

import org.glowroot.agent.plugin.api.Agent;
import org.glowroot.agent.plugin.api.Logger;
import org.glowroot.agent.plugin.api.ThreadContext;
import org.glowroot.agent.plugin.api.weaving.BindClassMeta;
import org.glowroot.agent.plugin.api.weaving.BindReceiver;
import org.glowroot.agent.plugin.api.weaving.OnReturn;
import org.glowroot.agent.plugin.api.weaving.Pointcut;
import org.glowroot.agent.plugin.servlet.ServletAspect.HttpServletRequest;

public class RequestParameterAspect {

    private static final Logger logger = Agent.getLogger(RequestParameterAspect.class);

    @Pointcut(className = "javax.servlet.ServletRequest", methodName = "getParameter*",
            methodParameterTypes = {".."}, nestingGroup = "servlet-inner-call")
    public static class GetParameterAdvice {
        @OnReturn
        public static void onReturn(ThreadContext context, @BindReceiver Object req,
                @BindClassMeta RequestClassMeta requestClassMeta) {
            if (!(req instanceof HttpServletRequest)) {
                return;
            }
            HttpServletRequest request = (HttpServletRequest) req;
            // only now is it safe to get parameters (if parameters are retrieved before this, it
            // could prevent a servlet from choosing to read the underlying stream instead of using
            // the getParameter* methods) see SRV.3.1.1 "When Parameters Are Available"
            ServletMessageSupplier messageSupplier =
                    (ServletMessageSupplier) context.getServletMessageSupplier();
            if (messageSupplier == null || messageSupplier.isRequestParametersCaptured()) {
                return;
            }
            // the request is being traced and the parameter map hasn't been captured yet
            captureRequestParameters(requestClassMeta, request, messageSupplier);
        }

        private static void captureRequestParameters(RequestClassMeta requestClassMeta,
                HttpServletRequest request, ServletMessageSupplier messageSupplier) {
            if (requestClassMeta.isBadParameterMapImplementation()) {
                messageSupplier.setCaptureRequestParameters(
                        DetailCapture.captureRequestParameters(request));
                return;
            }
            Map</*@Nullable*/ String, /*@Nullable*/ String /*@Nullable*/[]> parameterMap;
            try {
                parameterMap = request.getParameterMap();
            } catch (Exception e) {
                // this is to handle at least one web container (ATG 9.4) which has a bad
                // implementation of getParameterMap(), specifically in ATG's case
                // atg.taglib.dspjsp.RequestWrapper delegates the other getParameter*() methods but
                // it fails to delegate getParameterMap(), which then falls through to super class
                // atg.servlet.MutableHttpServletRequest and generates a NullPointerException since
                // the super class was not set up expecting the call

                // log exception at debug level
                logger.debug(e.getMessage(), e);
                // set flag so don't keep generating/catching exception over and over
                requestClassMeta.setBadParameterMapImplementation();
                messageSupplier.setCaptureRequestParameters(
                        DetailCapture.captureRequestParameters(request));
                return;
            }
            if (parameterMap == null) {
                return;
            }
            messageSupplier.setCaptureRequestParameters(
                    DetailCapture.captureRequestParameters(parameterMap));
        }
    }
}