package org.opendaylight.controller.netconf.nettyutil.handler;
import com.google.common.base.Preconditions;
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
import org.openexi.proc.HeaderOptionsOutputType;
import org.openexi.proc.common.EXIOptions;
import org.openexi.proc.common.EXIOptionsException;
import org.openexi.proc.grammars.GrammarCache;
import org.openexi.sax.EXIReader;
import org.openexi.sax.Transmogrifier;
+import org.openexi.sax.TransmogrifierException;
+import org.xml.sax.EntityResolver;
+import org.xml.sax.InputSource;
public final class NetconfEXICodec {
/**
* of the stream. This is really useful, so let's output it now.
*/
private static final boolean OUTPUT_EXI_COOKIE = true;
+ /**
+ * OpenEXI does not allow us to directly prevent resolution of external entities. In order
+ * to prevent XXE attacks, we reuse a single no-op entity resolver.
+ */
+ private static final EntityResolver ENTITY_RESOLVER = new EntityResolver() {
+ @Override
+ public InputSource resolveEntity(final String publicId, final String systemId) {
+ return new InputSource();
+ }
+ };
+
+ /**
+ * Since we have a limited number of options we can have, instantiating a weak cache
+ * will allow us to reuse instances where possible.
+ */
+ private static final LoadingCache<Short, GrammarCache> GRAMMAR_CACHES = CacheBuilder.newBuilder().weakValues().build(new CacheLoader<Short, GrammarCache>() {
+ @Override
+ public GrammarCache load(final Short key) {
+ return new GrammarCache(key);
+ }
+ });
+
+ /**
+ * Grammar cache acts as a template and is duplicated by the Transmogrifier and the Reader
+ * before use. It is safe to reuse a single instance.
+ */
+ private final GrammarCache exiGrammarCache;
private final EXIOptions exiOptions;
public NetconfEXICodec(final EXIOptions exiOptions) {
this.exiOptions = Preconditions.checkNotNull(exiOptions);
+ this.exiGrammarCache = createGrammarCache(exiOptions);
}
- private GrammarCache getGrammarCache() {
+ private static GrammarCache createGrammarCache(final EXIOptions exiOptions) {
short go = GrammarOptions.DEFAULT_OPTIONS;
if (exiOptions.getPreserveComments()) {
go = GrammarOptions.addCM(go);
go = GrammarOptions.addPI(go);
}
- return new GrammarCache(null, go);
+ return GRAMMAR_CACHES.getUnchecked(go);
}
EXIReader getReader() throws EXIOptionsException {
final EXIReader r = new EXIReader();
r.setPreserveLexicalValues(exiOptions.getPreserveLexicalValues());
- r.setGrammarCache(getGrammarCache());
+ r.setGrammarCache(exiGrammarCache);
+ r.setEntityResolver(ENTITY_RESOLVER);
return r;
}
- Transmogrifier getTransmogrifier() throws EXIOptionsException {
+ Transmogrifier getTransmogrifier() throws EXIOptionsException, TransmogrifierException {
final Transmogrifier transmogrifier = new Transmogrifier();
transmogrifier.setAlignmentType(exiOptions.getAlignmentType());
transmogrifier.setBlockSize(exiOptions.getBlockSize());
- transmogrifier.setGrammarCache(getGrammarCache());
+ transmogrifier.setGrammarCache(exiGrammarCache);
transmogrifier.setOutputCookie(OUTPUT_EXI_COOKIE);
transmogrifier.setOutputOptions(HeaderOptionsOutputType.all);
+ transmogrifier.setResolveExternalGeneralEntities(false);
return transmogrifier;
}
}