/*
* File: ListDatastreams.java
*
* Copyright 2009 2DC
*
* 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 melcoe.fedora.pep.rest.objectshandlers;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URI;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import melcoe.fedora.pep.PEPException;
import melcoe.fedora.pep.rest.filters.AbstractFilter;
import melcoe.fedora.pep.rest.filters.DataResponseWrapper;
import melcoe.fedora.util.LogUtil;
import melcoe.xacml.MelcoeXacmlException;
import melcoe.xacml.util.ContextUtil;
import org.apache.log4j.Logger;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.tidy.Tidy;
import com.sun.xacml.attr.AnyURIAttribute;
import com.sun.xacml.attr.AttributeValue;
import com.sun.xacml.attr.DateTimeAttribute;
import com.sun.xacml.attr.StringAttribute;
import com.sun.xacml.ctx.RequestCtx;
import com.sun.xacml.ctx.ResponseCtx;
import com.sun.xacml.ctx.Result;
import com.sun.xacml.ctx.Status;
import fedora.common.Constants;
/**
* Handles the ListDatastreams operation.
*
* @author nish.naidoo@gmail.com
*/
public class ListDatastreams
extends AbstractFilter {
private static Logger log =
Logger.getLogger(ListDatastreams.class.getName());
private ContextUtil contextUtil = null;
private Transformer xFormer = null;
private Tidy tidy = null;
/**
* Default constructor.
*
* @throws PEPException
*/
public ListDatastreams()
throws PEPException {
super();
contextUtil = new ContextUtil();
try {
TransformerFactory xFactory = TransformerFactory.newInstance();
xFormer = xFactory.newTransformer();
} catch (TransformerConfigurationException tce) {
throw new PEPException("Error initialising SearchFilter", tce);
}
tidy = new Tidy();
tidy.setShowWarnings(false);
tidy.setQuiet(true);
}
/*
* (non-Javadoc)
* @see
* melcoe.fedora.pep.rest.filters.RESTFilter#handleRequest(javax.servlet
* .http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
*/
public RequestCtx handleRequest(HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
if (log.isDebugEnabled()) {
log.debug(this.getClass().getName() + "/handleRequest!");
}
String path = request.getPathInfo();
String[] parts = path.split("/");
String pid = parts[1];
String asOfDateTime = request.getParameter("asOfDateTime");
if (!isDate(asOfDateTime)) {
asOfDateTime = null;
}
RequestCtx req = null;
Map<URI, AttributeValue> actions = new HashMap<URI, AttributeValue>();
Map<URI, AttributeValue> resAttr = new HashMap<URI, AttributeValue>();
try {
if (pid != null && !"".equals(pid)) {
resAttr.put(Constants.OBJECT.PID.getURI(),
new StringAttribute(pid));
}
if (pid != null && !"".equals(pid)) {
resAttr.put(new URI(XACML_RESOURCE_ID),
new AnyURIAttribute(new URI(pid)));
}
if (asOfDateTime != null && !"".equals(asOfDateTime)) {
resAttr.put(Constants.DATASTREAM.AS_OF_DATETIME.getURI(),
DateTimeAttribute.getInstance(asOfDateTime));
}
actions.put(Constants.ACTION.ID.getURI(),
new StringAttribute(Constants.ACTION.LIST_DATASTREAMS
.getURI().toASCIIString()));
actions.put(Constants.ACTION.API.getURI(),
new StringAttribute(Constants.ACTION.APIA.getURI()
.toASCIIString()));
req =
getContextHandler().buildRequest(getSubjects(request),
actions,
resAttr,
getEnvironment(request));
LogUtil.statLog(request.getRemoteUser(),
Constants.ACTION.LIST_DATASTREAMS.getURI()
.toASCIIString(),
pid,
null);
} catch (Exception e) {
log.error(e.getMessage(), e);
throw new ServletException(e.getMessage(), e);
}
return req;
}
/*
* (non-Javadoc)
* @see
* melcoe.fedora.pep.rest.filters.RESTFilter#handleResponse(javax.servlet
* .http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
*/
public RequestCtx handleResponse(HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
DataResponseWrapper res = (DataResponseWrapper) response;
byte[] data = res.getData();
String result = null;
String body = new String(data);
if (body.startsWith("<html>")) {
if (log.isDebugEnabled()) {
log.debug("filtering html");
}
result = filterHTML(request, res);
} else if (body.startsWith("<?xml")) {
if (log.isDebugEnabled()) {
log.debug("filtering html");
}
result = filterXML(request, res);
} else {
if (log.isDebugEnabled()) {
log.debug("not filtering due to unexpected output: " + body);
}
result = body;
}
res.setData(result.getBytes());
return null;
}
/**
* Parses an HTML based response and removes the items that are not
* permitted.
*
* @param request
* the http servlet request
* @param response
* the http servlet response
* @return the new response body without non-permissable objects.
* @throws ServletException
*/
private String filterHTML(HttpServletRequest request,
DataResponseWrapper response)
throws ServletException {
String path = request.getPathInfo();
String[] parts = path.split("/");
String pid = parts[1];
String body = new String(response.getData());
InputStream is = new ByteArrayInputStream(body.getBytes());
Document doc = tidy.parseDOM(is, null);
XPath xpath = XPathFactory.newInstance().newXPath();
NodeList rows = null;
try {
rows =
(NodeList) xpath.evaluate("//table[2]/tr",
doc,
XPathConstants.NODESET);
if (log.isDebugEnabled()) {
log.debug("number of rows found: " + rows.getLength());
}
} catch (XPathExpressionException xpe) {
throw new ServletException("Error parsing HTML for search results: ",
xpe);
}
// only the header row, no results.
if (rows.getLength() < 2) {
if (log.isDebugEnabled()) {
log.debug("No results to filter.");
}
return body;
}
Map<String, Node> dsids = new HashMap<String, Node>();
for (int x = 1; x < rows.getLength(); x++) {
NodeList elements = rows.item(x).getChildNodes();
String dsid = elements.item(0).getFirstChild().getNodeValue();
if (log.isDebugEnabled()) {
log.debug("dsid: " + dsid);
}
dsids.put(dsid, rows.item(x));
}
Set<Result> results =
evaluatePids(dsids.keySet(), pid, request, response);
for (Result r : results) {
if (r.getResource() == null || "".equals(r.getResource())) {
log
.warn("This resource has no resource identifier in the xacml response results!");
} else if (log.isDebugEnabled()) {
log.debug("Checking: " + r.getResource());
}
String[] ridComponents = r.getResource().split("\\/");
String rid = ridComponents[ridComponents.length - 1];
if (r.getStatus().getCode().contains(Status.STATUS_OK)
&& r.getDecision() != Result.DECISION_PERMIT) {
Node node = dsids.get(rid);
node.getParentNode().removeChild(node);
if (log.isDebugEnabled()) {
log.debug("Removing: " + r.getResource() + "[" + rid + "]");
}
}
}
Source src = new DOMSource(doc);
ByteArrayOutputStream os = new ByteArrayOutputStream();
javax.xml.transform.Result dst = new StreamResult(os);
try {
xFormer.transform(src, dst);
} catch (TransformerException te) {
throw new ServletException("error generating output", te);
}
return new String(os.toByteArray());
}
/**
* Parses an XML based response and removes the items that are not
* permitted.
*
* @param request
* the http servlet request
* @param response
* the http servlet response
* @return the new response body without non-permissable objects.
* @throws ServletException
*/
private String filterXML(HttpServletRequest request,
DataResponseWrapper response)
throws ServletException {
String body = new String(response.getData());
DocumentBuilder docBuilder = null;
Document doc = null;
try {
docBuilder =
DocumentBuilderFactory.newInstance().newDocumentBuilder();
doc =
docBuilder.parse(new ByteArrayInputStream(response
.getData()));
} catch (Exception e) {
throw new ServletException(e);
}
XPath xpath = XPathFactory.newInstance().newXPath();
String pid = null;
NodeList datastreams = null;
try {
pid = xpath.evaluate("/objectDatastreams/@pid", doc);
if (log.isDebugEnabled()) {
log.debug("filterXML: pid = [" + pid + "]");
}
datastreams =
(NodeList) xpath.evaluate("/objectDatastreams/datastream",
doc,
XPathConstants.NODESET);
} catch (XPathExpressionException xpe) {
throw new ServletException("Error parsing HTML for search results: ",
xpe);
}
if (datastreams.getLength() == 0) {
if (log.isDebugEnabled()) {
log.debug("No results to filter.");
}
return body;
}
Map<String, Node> dsids = new HashMap<String, Node>();
for (int x = 0; x < datastreams.getLength(); x++) {
String dsid =
datastreams.item(x).getAttributes().getNamedItem("dsid")
.getNodeValue();
dsids.put(dsid, datastreams.item(x));
}
Set<Result> results =
evaluatePids(dsids.keySet(), pid, request, response);
for (Result r : results) {
if (r.getResource() == null || "".equals(r.getResource())) {
log
.warn("This resource has no resource identifier in the xacml response results!");
} else if (log.isDebugEnabled()) {
log.debug("Checking: " + r.getResource());
}
String[] ridComponents = r.getResource().split("\\/");
String rid = ridComponents[ridComponents.length - 1];
if (r.getStatus().getCode().contains(Status.STATUS_OK)
&& r.getDecision() != Result.DECISION_PERMIT) {
Node node = dsids.get(rid);
node.getParentNode().removeChild(node);
if (log.isDebugEnabled()) {
log.debug("Removing: " + r.getResource() + "[" + rid + "]");
}
}
}
Source src = new DOMSource(doc);
ByteArrayOutputStream os = new ByteArrayOutputStream();
javax.xml.transform.Result dst = new StreamResult(os);
try {
xFormer.transform(src, dst);
} catch (TransformerException te) {
throw new ServletException("error generating output", te);
}
return new String(os.toByteArray());
}
/**
* Takes a given list of PID's and evaluates them.
*
* @param dsids
* the list of pids to check
* @param request
* the http servlet request
* @param response
* the http servlet resposne
* @return a set of XACML results.
* @throws ServletException
*/
private Set<Result> evaluatePids(Set<String> dsids,
String pid,
HttpServletRequest request,
DataResponseWrapper response)
throws ServletException {
Set<String> requests = new HashSet<String>();
for (String dsid : dsids) {
if (log.isDebugEnabled()) {
log.debug("Checking: " + pid + "/" + dsid);
}
Map<URI, AttributeValue> actions =
new HashMap<URI, AttributeValue>();
Map<URI, AttributeValue> resAttr =
new HashMap<URI, AttributeValue>();
try {
actions.put(Constants.ACTION.ID.getURI(),
new StringAttribute(Constants.ACTION.GET_DATASTREAM
.getURI().toASCIIString()));
resAttr.put(Constants.OBJECT.PID.getURI(),
new StringAttribute(pid));
resAttr.put(new URI(XACML_RESOURCE_ID),
new AnyURIAttribute(new URI(pid)));
resAttr.put(Constants.DATASTREAM.ID.getURI(),
new StringAttribute(dsid));
RequestCtx req =
getContextHandler()
.buildRequest(getSubjects(request),
actions,
resAttr,
getEnvironment(request));
String r = contextUtil.makeRequestCtx(req);
if (log.isDebugEnabled()) {
log.debug(r);
}
requests.add(r);
} catch (Exception e) {
log.error(e.getMessage(), e);
throw new ServletException(e.getMessage(), e);
}
}
String res = null;
ResponseCtx resCtx = null;
try {
if (log.isDebugEnabled()) {
log.debug("Number of requests: " + requests.size());
}
res =
getContextHandler().evaluateBatch(requests
.toArray(new String[requests.size()]));
if (log.isDebugEnabled()) {
log.debug("Response: " + res);
}
resCtx = contextUtil.makeResponseCtx(res);
} catch (MelcoeXacmlException pe) {
throw new ServletException("Error evaluating pids: "
+ pe.getMessage(), pe);
}
@SuppressWarnings("unchecked")
Set<Result> results = resCtx.getResults();
return results;
}
}