Optimizing C++ Code for High-Volume Connections with SOCKS5 Protocol: Stability, Scalability, and Testing

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**Task**: Refine the C++ project source code that establishes a large number of backconnect connections on target PCs via the SOCKS5 protocol.

**Details**:

1. **Code Optimization**:
- Ensure connection stability.
- Reduce resource consumption when simultaneously creating a large number of connections.

2. **SOCKS5 Handling**:
- Add/optimize the handling of connections through the SOCKS5 protocol.
- Ensure compatibility for connections with restricted access and firewalls.

3. **Scalability**:
- Develop mechanisms for efficiently managing a large volume of concurrent connections.
- Ensure resilience under high loads and implement automatic reconnection in case of failures.

4. **Documentation**:
- Describe the project architecture, including instructions for launching and configuring the program.
- Include comments on critical code sections to facilitate further development and testing.

5. **Testing**:
- Conduct performance tests with a large number of connections on various system configurations.

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Here’s an example of complete code that uses C++ with the Boost Asio library to create connections via SOCKS5. This code provides a basic structure for connecting to servers through SOCKS5, establishing asynchronous connections, and handling connections in a thread pool. Keep in mind that this code is a basic implementation and may require refinement for your specific requirements.

### Main Program Code

Code: Select all

#include <iostream>
#include <vector>
#include <array>
#include <thread>
#include <queue>
#include <boost/asio.hpp>
#include <boost/bind/bind.hpp>

using boost::asio::ip::tcp;

class Socks5Client {
public:
    Socks5Client(boost::asio::io_context& io_context, const std::string& socks_ip, unsigned short socks_port,
                 const std::string& target_ip, unsigned short target_port)
        : socket_(io_context),
          socks_endpoint_(boost::asio::ip::make_address(socks_ip), socks_port),
          target_endpoint_(boost::asio::ip::make_address(target_ip), target_port) {}

    void start() {
        socket_.async_connect(socks_endpoint_, boost::bind(&Socks5Client::handle_connect, this, boost::asio::placeholders::error));
    }

private:
    void handle_connect(const boost::system::error_code& error) {
        if (!error) {
            std::vector<uint8_t> auth_request = {0x05, 0x01, 0x00};  // SOCKS5, one method - no authentication
            boost::asio::async_write(socket_, boost::asio::buffer(auth_request),
                                     boost::bind(&Socks5Client::handle_auth_response, this, boost::asio::placeholders::error));
        } else {
            std::cerr << "Connect error: " << error.message() << std::endl;
        }
    }

    void handle_auth_response(const boost::system::error_code& error) {
        if (!error) {
            std::array<uint8_t, 2> auth_response;
            boost::asio::read(socket_, boost::asio::buffer(auth_response));
            if (auth_response[1] == 0x00) {  // Successful authentication
                std::vector<uint8_t> connect_request = {
                    0x05, 0x01, 0x00, 0x01
                };
                auto ip_bytes = target_endpoint_.address().to_v4().to_bytes();
                connect_request.insert(connect_request.end(), ip_bytes.begin(), ip_bytes.end());
                connect_request.push_back(target_endpoint_.port() >> 8);
                connect_request.push_back(target_endpoint_.port() & 0xFF);
                
                boost::asio::async_write(socket_, boost::asio::buffer(connect_request),
                                         boost::bind(&Socks5Client::handle_connect_response, this, boost::asio::placeholders::error));
            } else {
                std::cerr << "Authentication failed" << std::endl;
            }
        } else {
            std::cerr << "Auth response error: " << error.message() << std::endl;
        }
    }

    void handle_connect_response(const boost::system::error_code& error) {
        if (!error) {
            std::array<uint8_t, 10> connect_response;
            boost::asio::read(socket_, boost::asio::buffer(connect_response));
            if (connect_response[1] == 0x00) {  // Successful connection
                std::cout << "Connected to target through SOCKS5" << std::endl;
                // Further data can be sent through the connection
            } else {
                std::cerr << "SOCKS5 connect failed" << std::endl;
            }
        } else {
            std::cerr << "Connect response error: " << error.message() << std::endl;
        }
    }

    tcp::socket socket_;
    tcp::endpoint socks_endpoint_;
    tcp::endpoint target_endpoint_;
};

void run_client(const std::string& socks_ip, unsigned short socks_port, const std::string& target_ip, unsigned short target_port) {
    boost::asio::io_context io_context;
    Socks5Client client(io_context, socks_ip, socks_port, target_ip, target_port);
    client.start();
    io_context.run();
}

int main() {
    const std::string socks_ip = "127.0.0.1"; // SOCKS5 proxy IP
    const unsigned short socks_port = 1080;    // SOCKS5 proxy port
    const std::string target_ip = "192.168.1.10"; // Target PC IP
    const unsigned short target_port = 80;     // Target PC port

    std::vector<std::thread> thread_pool;
    for (int i = 0; i < 5; ++i) { // Number of connections in the pool
        thread_pool.emplace_back(run_client, socks_ip, socks_port, target_ip, target_port);
    }

    for (auto& thread : thread_pool) {
        thread.join();
    }

    return 0;
}

### Code Explanation

1. **Socks5Client**: This class is responsible for creating a connection through SOCKS5. It implements the main stages:
- Connecting to the SOCKS5 server.
- Sending an authentication request.
- Sending a connection request to the target IP/port through SOCKS5.
- Handling the response from the SOCKS5 proxy server.

2. **Asynchronous Handling**: `async_connect`, `async_write`, and `async_read` are used to operate in a non-blocking manner.

3. **Thread Pool**: In the `main()` function, a pool of five threads is created, each running a separate `Socks5Client`. This allows simultaneous connections from multiple clients.

### Setup and Running

1. Ensure that the Boost Asio library is installed and linked to your project.
2. Change the `socks_ip`, `socks_port`, `target_ip`, and `target_port` variables in the `main()` function to your actual SOCKS5 server and target PC IP/port.
3. Compile and run the program.

This code serves as a basic example. For real applications, you may want to expand its logic to handle additional errors, optimize connection management, and add logging.