Cisco DNS Proxy

When using JAXP SAX for parsing XML in Java, you can stop the parsing process after finding a certain field by throwing a SAXException when the desired condition is met. The SAX parser will catch the exception and stop the parsing operation.

Here's a basic example to illustrate how you can achieve this:

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import java.io.IOException;
import java.io.StringReader;

public class StopParsingExample {

    public static void main(String[] args) {
        String xmlData = "Value1Value2Value3";

        try {
            SAXParserFactory factory = SAXParserFactory.newInstance();
            SAXParser saxParser = factory.newSAXParser();

            MyHandler handler = new MyHandler();
            saxParser.parse(new InputSource(new StringReader(xmlData)), handler);

        } catch (ParserConfigurationException | SAXException | IOException e) {
            e.printStackTrace();
        }
    }

    private static class MyHandler extends DefaultHandler {
        private boolean stopParsing = false;

        @Override
        public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
            // Check if the desired field is found
            if ("field".equals(qName)) {
                String fieldValue = attributes.getValue("attr"); // Change "attr" to the actual attribute name
                if ("Value2".equals(fieldValue)) { // Change "Value2" to the desired value
                    stopParsing = true;
                    throw new SAXException("Stop parsing"); // Throw SAXException to stop parsing
                }
            }
        }

        @Override
        public void characters(char[] ch, int start, int length) throws SAXException {
            // Process character data if needed
        }

        @Override
        public void endElement(String uri, String localName, String qName) throws SAXException {
            // Perform actions when an element ends
        }

        @Override
        public void endDocument() throws SAXException {
            System.out.println("Parsing completed.");
        }
    }
}

In this example, the MyHandler class extends DefaultHandler, and the startElement method is overridden to check for the desired field. If the condition is met, it sets stopParsing to true and throws a SAXException. The parsing process will stop, and the endDocument method will be called.

Adjust the conditions and values according to your specific use case. Keep in mind that stopping parsing abruptly may not be a standard practice, and you should carefully consider the impact on your application's behavior.

To send a UDP request to a STUN server in C++, you can use the following example code. This example uses the boost::asio library for handling asynchronous I/O operations and boost::beast for handling UDP communication. Make sure you have the Boost library installed on your system before running this code.

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

namespace http = boost::beast::http;

using tcp = boost::asio::ip::tcp;
using udp = boost::asio::ip::udp;

int main(int argc, char* argv[]) {
  if (argc != 3) {
    std::cerr << "Usage: stun_udp_request  " << std::endl;
    return EXIT_FAILURE;
  }

  boost::asio::io_context ioc;
  udp::resolver resolver(ioc);
  udp::resolver::results_type results = resolver.resolve(argv[1], argv[2]);

  if (results.empty()) {
    std::cerr << "Cannot resolve: " << argv[1] << ":" << argv[2] << std::endl;
    return EXIT_FAILURE;
  }

  udp::socket udp_socket(ioc);
  udp_socket.connect(results.begin()->endpoint());

  // Prepare the STUN Binding Request
  std::string stun_request =
      "BINDING_REQUEST\r\n"
      "MIXED_RELAY\r\n"
      "USER-AGENT: STUN-UDP-Example\r\n"
      "\r\n";

  // Send the STUN Binding Request
  boost::system::error_code ignored_error;
  udp_socket.send_to(boost::asio::buffer(stun_request), results.begin()->endpoint(), 0, ignored_error);

  // Receive the STUN Binding Response
  boost::beast::flat_buffer buffer;
  http::response response;
  udp_socket.receive_message(buffer, response);

  // Print the STUN Binding Response
  std::cout << "STUN Binding Response:\n";
  std::cout << response.what() << std::endl;

  return EXIT_SUCCESS;
}

To compile the example, you can use the following command:

g++ -std=c++17 -o stun_udp_request stun_udp_request.cpp -lboost_system -lboost_as

Proxy "tunneling" should be understood as the isolation of traffic from the user. It allows you to form a fully protected channel for data exchange, which will be isolated from all other traffic.

The provider, when the user uses a VPN, "sees" only the encrypted traffic, as well as the address of the remote server to which the request is sent. But it is impossible to determine which site the user is visiting and what data is being sent.

The easiest way to set up a home proxy server is to install a router that supports this function. Then get the proxy data (provided by the service in which it is "rented") and enter it in the router settings. If there is no need for a common proxy (for all devices at once), then it should be configured separately for each device with the help of the utilities integrated in the OS for changing the connection properties.