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/*
* AcceptToken.java February 2014
*
* Copyright (C) 2014, Niall Gallagher <niallg@users.sf.net>
*
* 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.simpleframework.http.socket.service;
import static org.simpleframework.http.Protocol.SEC_WEBSOCKET_KEY;
import java.io.IOException;
import java.security.MessageDigest;
import org.simpleframework.common.encode.Base64Encoder;
import org.simpleframework.http.Request;
/**
* The <code>AcceptToken</code> is used to create a unique token based
* on a random key sent by the client. This is used to prove that the
* handshake was received, the server has to take two pieces of
* information and combine them to form a response. The first piece
* of information comes from the <code>Sec-WebSocket-Key</code> header
* field in the client handshake, the second is the globally unique
* identifier <code>258EAFA5-E914-47DA-95CA-C5AB0DC85B11</code>. Both
* are concatenated and an SHA-1 has is generated and used in the
* session initiating response.
*
* @author Niall Gallagher
*/
class AcceptToken {
/**
* This is the globally unique identifier used in the handshake.
*/
private static final byte[] MAGIC = {
'2', '5', '8', 'E', 'A', 'F', 'A', '5', '-',
'E', '9', '1', '4', '-', '4', '7', 'D', 'A',
'-', '9', '5', 'C', 'A', '-', 'C', '5', 'A',
'B', '0', 'D', 'C', '8', '5', 'B', '1', '1' };
/**
* This is used to generate the SHA-1 has from the user key.
*/
private final MessageDigest digest;
/**
* This is the original request used to initiate the session.
*/
private final Request request;
/**
* This is the character encoding to decode the key with.
*/
private final String charset;
/**
* Constructor for the <code>AcceptToken</code> object. This is
* to create an object that can generate a token from the client
* key available from the <code>Sec-WebSocket-Key</code> header.
*
* @param request this is the session initiating request
*/
public AcceptToken(Request request) throws Exception {
this(request, "SHA-1");
}
/**
* Constructor for the <code>AcceptToken</code> object. This is
* to create an object that can generate a token from the client
* key available from the <code>Sec-WebSocket-Key</code> header.
*
* @param request this is the session initiating request
* @param algorithm the algorithm used to create the token
*/
public AcceptToken(Request request, String algorithm) throws Exception {
this(request, algorithm, "UTF-8");
}
/**
* Constructor for the <code>AcceptToken</code> object. This is
* to create an object that can generate a token from the client
* key available from the <code>Sec-WebSocket-Key</code> header.
*
* @param request this is the session initiating request
* @param algorithm the algorithm used to create the token
* @param charset the encoding used to decode the client key
*/
public AcceptToken(Request request, String algorithm, String charset) throws Exception {
this.digest = MessageDigest.getInstance(algorithm);
this.request = request;
this.charset = charset;
}
/**
* This is used to create the required accept token for the session
* initiating response. The resulting token is a SHA-1 digest of
* the <code>Sec-WebSocket-Key</code> a globally unique identifier
* defined in RFC 6455 all encoded in base64.
*
* @return the accept token for the session initiating response
*/
public String create() throws IOException {
String value = request.getValue(SEC_WEBSOCKET_KEY);
byte[] data = value.getBytes(charset);
if (data.length > 0) {
digest.update(data);
digest.update(MAGIC);
}
byte[] digested = digest.digest();
char[] text = Base64Encoder.encode(digested);
return new String(text);
}
}
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