correct answer to well-formed but still unsatisfiable range request

main/frontend-webdav/src/main/java/org/cryptomator/frontend/webdav/jackrabbitservlet/DavFileWithRange.java

@@ -9,6 +9,7 @@ import java.util.Objects;
 import org.apache.commons.lang3.tuple.ImmutablePair;
 import org.apache.commons.lang3.tuple.Pair;
 import org.apache.jackrabbit.webdav.DavException;
+import org.apache.jackrabbit.webdav.DavServletResponse;
 import org.apache.jackrabbit.webdav.DavSession;
 import org.apache.jackrabbit.webdav.io.OutputContext;
 import org.apache.jackrabbit.webdav.lock.LockManager;
@@ -41,9 +42,10 @@ class DavFileWithRange extends DavFile {
 		try (ReadableFile src = node.openReadable(); OutputStream out = outputContext.getOutputStream()) {
 			final long contentLength = src.size();
 			final Pair<Long, Long> range = getEffectiveRange(contentLength);
-			assert range.getLeft() >= 0;
-			assert range.getLeft() <= range.getRight();
-			assert range.getRight() <= contentLength;
+			if (range.getLeft() < 0 || range.getLeft() > range.getRight() || range.getRight() > contentLength) {
+				outputContext.setProperty(HttpHeader.CONTENT_RANGE.asString(), "bytes */" + contentLength);
+				throw new UncheckedDavException(DavServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE, "Valid Range would be in [0, " + contentLength + "]");
+			}
 			final Long rangeLength = range.getRight() - range.getLeft() + 1;
 			outputContext.setContentLength(rangeLength);
 			outputContext.setProperty(HttpHeader.CONTENT_RANGE.asString(), contentRangeResponseHeader(range.getLeft(), range.getRight(), contentLength));

main/frontend-webdav/src/main/java/org/cryptomator/frontend/webdav/jackrabbitservlet/WebDavServlet.java

@@ -11,6 +11,8 @@ package org.cryptomator.frontend.webdav.jackrabbitservlet;
 import java.io.IOException;
 import java.net.URI;
 
+import javax.servlet.ServletException;
+
 import org.apache.commons.lang3.ArrayUtils;
 import org.apache.jackrabbit.webdav.DavException;
 import org.apache.jackrabbit.webdav.DavLocatorFactory;
@@ -82,6 +84,17 @@ public class WebDavServlet extends AbstractWebdavServlet {
 		throw new UnsupportedOperationException("Setting resourceFactory not supported.");
 	}
 
+	/* Unchecked DAV exception rewrapping */
+
+	@Override
+	protected boolean execute(WebdavRequest request, WebdavResponse response, int method, DavResource resource) throws ServletException, IOException, DavException {
+		try {
+			return super.execute(request, response, method, resource);
+		} catch (UncheckedDavException e) {
+			throw e.toDavException();
+		}
+	}
+
 	/* GET stuff */
 
 	@Override