How to Tunnel HTTP-Protocol with a Simple Java Proxy Server through a Firewall?

public static void main(final String[] args) {

readPropertyFile();

if (getLocalProxyPort() != -1) {

LOGGER.info("SWEC-PROXY-ADAPTER is ready at localhost:" + getLocalProxyPort());

try {

httpServerSocket = new ServerSocket(getLocalProxyPort());

final boolean listening = true;

while (listening) {

final Socket httpSocket = httpServerSocket.accept();

final SocketThread httpThread = new SocketThread(httpSocket);

httpThread.start();

}

} catch (final IOException e) {

LOGGER.log(Level.SEVERE, "could not listen port " + getLocalProxyPort());

}

}

}

The class SocketThread.java is the working thread of the socket connection. When you implement your own service on Google App Engine you have to change the URL in line 55 to your own application name.

Logging is done in the method loggingOfResult() because several thread write to console in parallel and this ensures that all output of a thread is written in one message.

SocketThread.java (lines 54-94):

// TODO: Change URL to your Google Appengine application

private static final String REMOTE_PROXY_SERVER_HTTPS_URL = "https://http-proxy-adapter-server.appspot.com/resources/server";

/**

* Ensures that messages from concurrent threads are logged in a block

*/

private final StringBuilder message = new StringBuilder();

/**

* Connection to the local web client

*/

private final Socket socket;

/**

* Helper to parse the HTTP request of the local web client

*/

private RequestHeader requestHeader;

/**

* Connection to remote server

*/

private HttpsURLConnection remoteConnection;

public SocketThread(final Socket socket) {

checkNotNull(socket);

this.socket = socket;

}

@Override

public void run() {

try {

readRequestFormLocalClient();

forwardLocalRequestToRemoteServer();

sendResponseToLocalClient();

loggingOfResult();

} catch (final IOException | IllegalStateException e) {

LOGGER.log(Level.WARNING, e.getMessage());

} finally {

closeSocket();

}

}

The file settings.ini has all parameters for the HttpProxyAdapterClient. You may select a different port number for the proxy server (don't forget to set the port in your web browser).

Settings.ini.java (lines 1-9)

# settings for http-proxy-adapter-client

local.http.proxyPort=2443

# settings for corporate and/or private proxy server

https.proxySet=false

https.proxyUserName=<your windows domain>\\<your windows user ide>

https.proxyUserPwd=<your windows user password>

https.proxyPort=<port number>

https.proxyHost=<domain name>

@POST

@Consumes("text/plain")

public Response forwardRequestService(final String httpMessage) {

try {

// If the caller don't knows the token access is not allowed

if (!httpMessage.contains(SecretToken.TOKEN_VALUE)) {

return Response.status(Status.UNAUTHORIZED).build();

}

// Everything except GET & HEAD is not allowed

final RequestHeader requestHeader = new RequestHeader(httpMessage);

if (!"GET".equals(requestHeader.getType()) &&

!"HEAD".equals(requestHeader.getType())) {

return Response.status(HttpURLConnection.HTTP_NOT_IMPLEMENTED).build();

}

final URL url = new URL(requestHeader.getUrl());

final HttpURLConnection connectionHttp = (HttpURLConnection) url.openConnection();

connectionHttp.setRequestMethod(requestHeader.getType());

for (final String key: requestHeader.getParameter().keySet()) {

if (isNotSecretToken(key)) {

String value = requestHeader.getParameter().get(key);

connectionHttp.addRequestProperty(key, value);

}

}

// Send response back to client

final ByteArrayOutputStream baos = new ByteArrayOutputStream();

final DataInputStream dis = new DataInputStream(connectionHttp.getInputStream());

// Add response header

final StringBuilder sb = new StringBuilder();

sb.append(requestHeader.getHttpVersion() + " " +

connectionHttp.getResponseCode() + " " +

connectionHttp.getResponseMessage() + "\r\n");

final Map < String, List < String >> map = connectionHttp.getHeaderFields();

for (final Map.Entry < String, List < String >> entry: map.entrySet()) {

final String key = entry.getKey();

sb.append(key + " : " + entry.getValue().toString().replace("[", "")

.replace("]", "").replace(",", " ") +

"\r\n");

}

sb.append("\r\n");

// Add response content

baos.write(sb.toString().getBytes(), 0, sb.toString().getBytes().length);

final byte[] data = new byte[(int) Short.MAX_VALUE];

int index = dis.read(data, 0, (int) Short.MAX_VALUE);

while (index != -1) {

baos.write(data, 0, index);

index = dis.read(data, 0, (int) Short.MAX_VALUE);

}

final byte[] result = baos.toByteArray();

return Response.ok(result).build();

} catch (final MalformedURLException e) {

System.out.print("MalformedURLException " + e.getMessage());

return Response.status(Status.BAD_REQUEST).entity(e.getMessage()).build();

} catch (final IOException e) {

System.out.print("IOException " + e.getMessage());

return Response.status(Status.BAD_REQUEST).entity(e.getMessage()).build();

}

}