/*
* Copyright 2014-2015 the original author or authors.
*
* 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 org.springframework.xd.dirt.integration.bus;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.util.HashMap;
import java.util.Map;
import javax.xml.bind.DatatypeConverter;
import org.springframework.integration.IntegrationMessageHeaderAccessor;
import org.springframework.integration.support.json.Jackson2JsonObjectMapper;
import org.springframework.messaging.Message;
/**
* Encodes requested headers into payload with format
* {@code 0xff, n(1), [ [lenHdr(1), hdr, lenValue(4), value] ... ]}.
* The 0xff indicates this new format; n is number of headers (max 255); for
* each header, the name length (1 byte) is followed by the name, followed by
* the value length (int) followed by the value (json).
* <p>
* Previously, there was no leading 0xff; the value length was 1 byte and only
* String header values were supported (no JSON conversion).
*
* @author Eric Bottard
* @author Gary Russell
*/
public class EmbeddedHeadersMessageConverter {
private final Jackson2JsonObjectMapper objectMapper = new Jackson2JsonObjectMapper();
public static String decodeExceptionMessage(Message<?> requestMessage) {
return "Could not convert message: " + DatatypeConverter.printHexBinary((byte[]) requestMessage.getPayload());
}
/**
* Return a new message where some of the original headers of {@code original}
* have been embedded into the new message payload.
*/
public byte[] embedHeaders(MessageValues original, String... headers) throws Exception {
byte[][] headerValues = new byte[headers.length][];
int n = 0;
int headerCount = 0;
int headersLength = 0;
for (String header : headers) {
Object value = original.get(header) == null ? null
: original.get(header);
if (value != null) {
String json = this.objectMapper.toJson(value);
headerValues[n] = json.getBytes("UTF-8");
headerCount++;
headersLength += header.length() + headerValues[n++].length;
}
else {
headerValues[n++] = null;
}
}
// 0xff, n(1), [ [lenHdr(1), hdr, lenValue(4), value] ... ]
byte[] newPayload = new byte[((byte[])original.getPayload()).length + headersLength + headerCount * 5 + 2];
ByteBuffer byteBuffer = ByteBuffer.wrap(newPayload);
byteBuffer.put((byte) 0xff); // signal new format
byteBuffer.put((byte) headerCount);
for (int i = 0; i < headers.length; i++) {
if (headerValues[i] != null) {
byteBuffer.put((byte) headers[i].length());
byteBuffer.put(headers[i].getBytes("UTF-8"));
byteBuffer.putInt(headerValues[i].length);
byteBuffer.put(headerValues[i]);
}
}
byteBuffer.put((byte[])original.getPayload());
return byteBuffer.array();
}
/**
* Return a message where headers, that were originally embedded into the payload, have been promoted
* back to actual headers. The new payload is now the original payload.
*
* @param message the message to extract headers
* @param copyRequestHeaders boolean value to specify if original headers should be copied
*/
public MessageValues extractHeaders(Message<byte[]> message, boolean copyRequestHeaders) throws Exception {
byte[] bytes = message.getPayload();
ByteBuffer byteBuffer = ByteBuffer.wrap(bytes);
int headerCount = byteBuffer.get() & 0xff;
if (headerCount < 255) {
return oldExtractHeaders(byteBuffer, bytes, headerCount, message, copyRequestHeaders);
}
else {
headerCount = byteBuffer.get() & 0xff;
Map<String, Object> headers = new HashMap<String, Object>();
for (int i = 0; i < headerCount; i++) {
int len = byteBuffer.get() & 0xff;
String headerName = new String(bytes, byteBuffer.position(), len, "UTF-8");
byteBuffer.position(byteBuffer.position() + len);
len = byteBuffer.getInt();
String headerValue = new String(bytes, byteBuffer.position(), len, "UTF-8");
Object headerContent = this.objectMapper.fromJson(headerValue, Object.class);
headers.put(headerName, headerContent);
byteBuffer.position(byteBuffer.position() + len);
}
byte[] newPayload = new byte[byteBuffer.remaining()];
byteBuffer.get(newPayload);
return buildMessageValues(message, newPayload, headers, copyRequestHeaders);
}
}
private MessageValues oldExtractHeaders(ByteBuffer byteBuffer, byte[] bytes, int headerCount,
Message<byte[]> message, boolean copyRequestHeaders)
throws UnsupportedEncodingException {
Map<String, Object> headers = new HashMap<String, Object>();
for (int i = 0; i < headerCount; i++) {
int len = byteBuffer.get();
String headerName = new String(bytes, byteBuffer.position(), len, "UTF-8");
byteBuffer.position(byteBuffer.position() + len);
len = byteBuffer.get() & 0xff;
String headerValue = new String(bytes, byteBuffer.position(), len, "UTF-8");
byteBuffer.position(byteBuffer.position() + len);
if (IntegrationMessageHeaderAccessor.SEQUENCE_NUMBER.equals(headerName)
|| IntegrationMessageHeaderAccessor.SEQUENCE_SIZE.equals(headerName)) {
headers.put(headerName, Integer.parseInt(headerValue));
}
else {
headers.put(headerName, headerValue);
}
}
byte[] newPayload = new byte[byteBuffer.remaining()];
byteBuffer.get(newPayload);
return buildMessageValues(message, newPayload, headers, copyRequestHeaders);
}
private MessageValues buildMessageValues(Message<byte[]> message, byte[] payload, Map<String, Object> headers,
boolean copyRequestHeaders) {
MessageValues messageValues = new MessageValues(payload, headers);
if (copyRequestHeaders) {
messageValues.copyHeadersIfAbsent(message.getHeaders());
}
return messageValues;
}
}