google-nomulus/java/google/registry/security/JsonHttp.java
Michael Muller c458c05801 Rename Java packages to use the .google TLD
The dark lord Gosling designed the Java package naming system so that
ownership flows from the DNS system. Since we own the domain name
registry.google, it seems only appropriate that we should use
google.registry as our package name.
2016-05-13 20:04:42 -04:00

98 lines
3.6 KiB
Java

// Copyright 2016 The Domain Registry Authors. All Rights Reserved.
//
// 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 google.registry.security;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.net.HttpHeaders.CONTENT_DISPOSITION;
import static com.google.common.net.HttpHeaders.X_CONTENT_TYPE_OPTIONS;
import static com.google.common.net.MediaType.JSON_UTF_8;
import static org.json.simple.JSONValue.writeJSONString;
import com.google.common.net.MediaType;
import google.registry.util.FormattingLogger;
import org.json.simple.JSONValue;
import org.json.simple.parser.ParseException;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer;
import java.util.Map;
import javax.annotation.Nullable;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Helper class for servlets that read or write JSON.
*
* @see JsonResponseHelper
*/
public final class JsonHttp {
private static final FormattingLogger logger = FormattingLogger.getLoggerForCallerClass();
/** String prefixed to all JSON-like responses. */
public static final String JSON_SAFETY_PREFIX = ")]}'\n";
/**
* Extracts a JSON object from a servlet request.
*
* @return JSON object or {@code null} on error, in which case servlet should return.
* @throws IOException if we failed to read from {@code req}.
*/
@Nullable
@SuppressWarnings("unchecked")
public static Map<String, ?> read(HttpServletRequest req) throws IOException {
if (!"POST".equals(req.getMethod())
&& !"PUT".equals(req.getMethod())) {
logger.warning("JSON request payload only allowed for POST/PUT");
return null;
}
if (!JSON_UTF_8.is(MediaType.parse(req.getContentType()))) {
logger.warningfmt("Invalid JSON Content-Type: %s", req.getContentType());
return null;
}
try (Reader jsonReader = req.getReader()) {
try {
return checkNotNull((Map<String, ?>) JSONValue.parseWithException(jsonReader));
} catch (ParseException | NullPointerException | ClassCastException e) {
logger.warning(e, "Malformed JSON");
return null;
}
}
}
/**
* Writes a JSON servlet response securely with a parser breaker.
*
* @throws IOException if we failed to write to {@code rsp}.
*/
public static void write(HttpServletResponse rsp, Map<String, ?> jsonObject) throws IOException {
checkNotNull(jsonObject);
rsp.setContentType(JSON_UTF_8.toString());
// This prevents IE from MIME-sniffing a response away from the declared Content-Type.
rsp.setHeader(X_CONTENT_TYPE_OPTIONS, "nosniff");
// This is a defense in depth that prevents browsers from trying to render the content of the
// response, even if all else fails. It's basically another anti-sniffing mechanism in the sense
// that if you hit this url directly, it would try to download the file instead of showing it.
rsp.setHeader(CONTENT_DISPOSITION, "attachment");
try (Writer writer = rsp.getWriter()) {
writer.write(JSON_SAFETY_PREFIX);
writeJSONString(jsonObject, writer);
}
}
}