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WebSocket client implementation in Java.
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/*
* Copyright (C) 2015-2016 Neo Visionaries Inc.
*
* 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 com.neovisionaries.ws.client;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.util.List;
import java.util.Map;
class ProxyHandshaker
{
private static final String RN = "\r\n";
private final String mHost;
private final int mPort;
private final ProxySettings mSettings;
public ProxyHandshaker(String host, int port, ProxySettings settings)
{
mHost = host;
mPort = port;
mSettings = settings;
}
public void perform(Socket socket) throws IOException
{
// Send a CONNECT request to the proxy server.
sendRequest(socket);
// Receive a response.
receiveResponse(socket);
}
private void sendRequest(Socket socket) throws IOException
{
// Build a CONNECT request.
String request = buildRequest();
// Convert the request to a byte array.
byte[] requestBytes = Misc.getBytesUTF8(request);
// Get the stream to send data to the proxy server.
OutputStream output = socket.getOutputStream();
// Send the request to the proxy server.
output.write(requestBytes);
output.flush();
}
private String buildRequest()
{
String host = String.format("%s:%d", mHost, mPort);
// CONNECT
StringBuilder builder = new StringBuilder()
.append("CONNECT ").append(host).append(" HTTP/1.1").append(RN)
.append("Host: ").append(host).append(RN);
// Additional headers
addHeaders(builder);
// Proxy-Authorization
addProxyAuthorization(builder);
// The entire request.
return builder.append(RN).toString();
}
private void addHeaders(StringBuilder builder)
{
// For each additional header.
for (Map.Entry> header : mSettings.getHeaders().entrySet())
{
// Header name.
String name = header.getKey();
// For each header value.
for (String value : header.getValue())
{
if (value == null)
{
value = "";
}
builder.append(name).append(": ").append(value).append(RN);
}
}
}
private void addProxyAuthorization(StringBuilder builder)
{
String id = mSettings.getId();
if (id == null || id.length() == 0)
{
return;
}
String password = mSettings.getPassword();
if (password == null)
{
password = "";
}
// {id}:{password}
String credentials = String.format("%s:%s", id, password);
// The current implementation always uses Basic Authentication.
builder
.append("Proxy-Authorization: Basic ")
.append(Base64.encode(credentials))
.append(RN);
}
private void receiveResponse(Socket socket) throws IOException
{
// Get the stream to read data from the proxy server.
InputStream input = socket.getInputStream();
// Read the status line.
readStatusLine(input);
// Skip HTTP headers, including an empty line (= the separator
// between the header part and the body part).
skipHeaders(input);
}
private void readStatusLine(InputStream input) throws IOException
{
// Read the status line.
String statusLine = Misc.readLine(input, "UTF-8");
// If the response from the proxy server does not contain a status line.
if (statusLine == null || statusLine.length() == 0)
{
throw new IOException("The response from the proxy server does not contain a status line.");
}
// Expect "HTTP/1.1 200 Connection established"
String[] elements = statusLine.split(" +", 3);
if (elements.length < 2)
{
throw new IOException(
"The status line in the response from the proxy server is badly formatted. " +
"The status line is: " + statusLine);
}
// If the status code is not "200".
if ("200".equals(elements[1]) == false)
{
throw new IOException(
"The status code in the response from the proxy server is not '200 Connection established'. " +
"The status line is: " + statusLine);
}
// OK. A connection was established.
}
private void skipHeaders(InputStream input) throws IOException
{
// The number of normal letters in a line.
int count = 0;
while (true)
{
// Read a byte from the stream.
int ch = input.read();
// If the end of the stream was reached.
if (ch == -1)
{
// Unexpected EOF.
throw new EOFException("The end of the stream from the proxy server was reached unexpectedly.");
}
// If the end of the line was reached.
if (ch == '\n')
{
// If there is no normal byte in the line.
if (count == 0)
{
// An empty line (the separator) was found.
return;
}
// Reset the counter and go to the next line.
count = 0;
continue;
}
// If the read byte is not a carriage return.
if (ch != '\r')
{
// Increment the number of normal bytes on the line.
++count;
continue;
}
// Read the next byte.
ch = input.read();
// If the end of the stream was reached.
if (ch == -1)
{
// Unexpected EOF.
throw new EOFException("The end of the stream from the proxy server was reached unexpectedly after a carriage return.");
}
if (ch != '\n')
{
// Regard the last '\r' as a normal byte as well as the current 'ch'.
count += 2;
continue;
}
// '\r\n' was detected.
// If there is no normal byte in the line.
if (count == 0)
{
// An empty line (the separator) was found.
return;
}
// Reset the counter and go to the next line.
count = 0;
}
}
/**
* To be able to verify the hostname of the certificate received
* if a connection is made to an https/wss endpoint, access to this
* hostname is required.
*
* @return the hostname of the server the proxy is asked to connect to.
*/
String getProxiedHostname()
{
return mHost;
}
}