/**
*
*/
package org.fcrepo.server.security.xacml.util;
import java.io.File;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.fcrepo.common.Constants;
import org.fcrepo.common.MalformedPIDException;
import org.fcrepo.common.PID;
import org.fcrepo.server.Context;
import org.fcrepo.server.ReadOnlyContext;
import org.fcrepo.server.Server;
import org.fcrepo.server.errors.ObjectNotInLowlevelStorageException;
import org.fcrepo.server.errors.ServerException;
import org.fcrepo.server.management.Management;
import org.fcrepo.server.security.xacml.MelcoeXacmlException;
import org.fcrepo.server.security.xacml.pdp.MelcoePDPException;
import org.fcrepo.server.storage.types.RelationshipTuple;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A RelationshipResolver that resolves relationships via
* {@link Management#getRelationships(org.fcrepo.server.Context, String, String)}.
*
* @author Edwin Shin
*/
public class RelationshipResolverImpl
implements RelationshipResolver {
private static final Logger logger =
LoggerFactory.getLogger(RelationshipResolverImpl.class);
/**
* Designates the repository itself. Policies can apply to the repository,
* but it is a special case, as it is not represented by a PID, and by
* definition, has no parents.
*/
private static String DEFAULT_RELATIONSHIP =
"info:fedora/fedora-system:def/relations-external#isMemberOf";
private final List<String> relationships;
private Management apim;
private Context fedoraCtx;
public RelationshipResolverImpl() {
this(new HashMap<String, String>());
}
/**
* Constructor that takes a map of parent-child predicates (relationships).
* {@link ContextHandlerImpl} builds the map from the relationship-resolver
* section of config-melcoe-pep.xml (in WEB-INF/classes).
*
* @param options
* @throws MelcoePDPException
*/
public RelationshipResolverImpl(Map<String, String> options) {
relationships = new ArrayList<String>();
// FIXME: should add default relationship if no parent-child-relationship option is present, instead of options being empty
if (options.isEmpty()) {
relationships.add(DEFAULT_RELATIONSHIP);
} else {
List<String> keys = new ArrayList<String>(options.keySet());
Collections.sort(keys);
for (String s : keys) {
if (s.startsWith("parent-child-relationship")) {
relationships.add(options.get(s));
}
}
}
}
/*
* (non-Javadoc)
* @see
* org.fcrepo.server.security.xacml.pdp.finder.support.RelationshipResolver#buildRESTParentHierarchy
* (java.lang.String)
*/
@Override
public String buildRESTParentHierarchy(String pid)
throws MelcoeXacmlException {
Set<String> parents = getParents(pid);
if (parents == null || parents.size() == 0) {
return "/" + pid;
}
String[] parentArray = parents.toArray(new String[parents.size()]);
return buildRESTParentHierarchy(parentArray[0]) + "/" + pid;
}
/*
* (non-Javadoc)
* @see
* org.fcrepo.server.security.xacml.pdp.finder.support.RelationshipResolver#getParents(java.
* lang.String)
*/
public Set<String> getParents(String pid) throws MelcoeXacmlException {
if (logger.isDebugEnabled()) {
logger.debug("Obtaining parents for: " + pid);
}
Set<String> parentPIDs = new HashSet<String>();
if (pid.equalsIgnoreCase(Constants.FEDORA_REPOSITORY_PID.uri)) {
return parentPIDs;
}
query: for (String relationship : relationships) {
if (logger.isDebugEnabled()) {
logger.debug("relationship query: " + pid + ", " + relationship);
}
Map<String, Set<String>> mapping;
try {
mapping = getRelationships(pid, relationship);
} catch (MelcoeXacmlException e) {
Throwable t = e.getCause();
// An object X, may legitimately declare a parent relation to
// another object, Y which does not exist. Therefore, we don't
// want to continue querying for Y's parents.
if (t != null && t instanceof ObjectNotInLowlevelStorageException) {
if (logger.isDebugEnabled()) {
logger.debug("Parent, " + pid + ", not found.");
}
break query;
} else {
// Unexpected error, so we throw back the original
throw e;
}
}
Set<String> parents = mapping.get(relationship);
if (parents != null) {
for (String parent : parents) {
PID parentPID = PID.getInstance(parent);
// we want the parents in demo:123 form, not info:fedora/demo:123
parentPIDs.add(parentPID.toString());
if (logger.isDebugEnabled()) {
logger.debug("added parent " + parentPID.toString());
}
}
}
}
return parentPIDs;
}
protected String getSubjectURI(String subject) throws MalformedPIDException {
String strippedSubject;
if (subject.startsWith(Constants.FEDORA.uri)) {
strippedSubject = subject.substring(Constants.FEDORA.uri.length());
} else {
strippedSubject = subject;
}
String parts[] = strippedSubject.split("/");
PID pid = new PID(parts[0]);
String subjectURI;
if (parts.length == 1) {
subjectURI = pid.toURI();
} else if (parts.length == 2) {
subjectURI = pid.toURI() + "/" + parts[1]; // add datastream
} else {
logger.warn("Invalid subject argument for getRelationships: " + subject + ". Should be pid or datastream (URI form optional");
subjectURI = null;
}
return subjectURI;
}
@Override
public Map<String, Set<String>> getRelationships(String subject)
throws MelcoeXacmlException {
return getRelationships(subject, null);
}
@Override
public Map<String, Set<String>> getRelationships(String subject,
String relationship)
throws MelcoeXacmlException {
String subjectURI;
try {
subjectURI = getSubjectURI(subject);
if (subjectURI == null) {
return new HashMap<String, Set<String>>();
}
} catch (MalformedPIDException e1) {
logger.warn("Invalid subject argument for getRelationships: " + subject + ". PID part of URI is malformed");
return new HashMap<String, Set<String>>();
}
RelationshipTuple[] tuples;
try {
tuples =
getApiM().getRelationships(getContext(),
subjectURI,
relationship);
// Anticipating searches which fail because the object identified by
// pid may not exist in the Fedora repository, since objects can
// declare parent relationships to objects that do not exist
} catch (ServerException e) {
throw new MelcoeXacmlException(e.getMessage(), e);
}
Map<String, Set<String>> relationships =
new HashMap<String, Set<String>>();
for (RelationshipTuple t : tuples) {
String p = t.predicate;
String o = t.object;
Set<String> values = relationships.get(p);
if (values == null) {
values = new HashSet<String>();
}
values.add(o);
relationships.put(p, values);
}
return relationships;
}
private Management getApiM() {
if (apim != null) {
return apim;
}
Server server;
try {
server = Server.getInstance(new File(Constants.FEDORA_HOME), false);
} catch (Exception e) {
logger.error(e.getMessage());
throw new RuntimeException("Failed getting instance of Fedora", e);
}
apim =
(Management) server
.getModule("org.fcrepo.server.management.Management");
return apim;
}
private Context getContext() throws MelcoeXacmlException {
if (fedoraCtx != null) {
return fedoraCtx;
}
try {
fedoraCtx =
ReadOnlyContext.getContext(null,
null,
null,
ReadOnlyContext.DO_OP);
} catch (Exception e) {
throw new MelcoeXacmlException(e.getMessage(), e);
}
return fedoraCtx;
}
/**
* Returns a PID object for the requested String. This method will return a
* PID for a variety of pid permutations, e.g. demo:1, info:fedora/demo:1,
* demo:1/DS1, info:fedora/demo:1/sdef:foo/sdep:bar/methodBaz.
*
* @param pid
* @return a PID object
*/
// FIXME: does not appear to be used anywhere
protected PID getNormalizedPID(String pid) {
// strip the leading "info:fedora/" if any
if (pid.startsWith(Constants.FEDORA.uri)) {
pid = pid.substring(Constants.FEDORA.uri.length());
}
// should be left with "demo:foo" or "demo:foo/demo:bar"
return PID.getInstance(pid.split("\\/")[0]);
}
@Override
public Set<String> getAttributesFromQuery(String query,
String queryLang,
String variable)
throws MelcoeXacmlException {
// can't run queries for a RELS relationship resolver
logger.warn("RELS relationship resolver does not support retrieving attributes with an RI query");
return Collections.emptySet();
}
}