// Copyright (c) 2015-present The Bitcoin Core developers

// Distributed under the MIT software license, see the accompanying

// file COPYING or http://www.opensource.org/licenses/mit-license.php.

/**

 * Functionality for communicating with Tor.

 */

#ifndef BITCOIN_TORCONTROL_H

#define BITCOIN_TORCONTROL_H

#include <netaddress.h>

#include <util/fs.h>

#include <util/sock.h>

#include <util/threadinterrupt.h>

#include <cstdint>

#include <deque>

#include <functional>

#include <memory>

#include <string>

#include <thread>

#include <vector>

constexpr uint16_t DEFAULT_TOR_SOCKS_PORT{9050};

constexpr int DEFAULT_TOR_CONTROL_PORT = 9051;

extern const std::string DEFAULT_TOR_CONTROL;

static const bool DEFAULT_LISTEN_ONION = true;

/** Tor control reply code. Ref: https://spec.torproject.org/control-spec/replies.html */

constexpr int TOR_REPLY_OK{250};

constexpr int TOR_REPLY_UNRECOGNIZED{510};

constexpr int TOR_REPLY_SYNTAX_ERROR{512}; //!< Syntax error in command argument

CService DefaultOnionServiceTarget(uint16_t port);

/** Reply from Tor, can be single or multi-line */

class TorControlReply

{

public:

    TorControlReply() { Clear(); }

    int code;

    std::vector<std::string> lines;

    void Clear()

    {

        code = 0;

        lines.clear();

    }

};

/** Low-level handling for Tor control connection.

 * Speaks the SMTP-like protocol as defined in torspec/control-spec.txt

 */

class TorControlConnection

{

public:

    typedef std::function<void(TorControlConnection &,const TorControlReply &)> ReplyHandlerCB;

    /** Create a new TorControlConnection.

     */

    explicit TorControlConnection(CThreadInterrupt& interrupt);

    ~TorControlConnection();

    /**

     * Connect to a Tor control port.

     * tor_control_center is address of the form host:port.

     * Return true on success.

     */

    bool Connect(const std::string& tor_control_center);

    /**

     * Disconnect from Tor control port.

     */

    void Disconnect();

    /** Send a command, register a handler for the reply.

     * A trailing CRLF is automatically added.

     * Return true on success.

     */

    bool Command(const std::string &cmd, const ReplyHandlerCB& reply_handler);

    /**

     * Check if the connection is established.

     */

    bool IsConnected() const;

    /**

     * Wait for data to be available on the socket.

     * @param[in] timeout Maximum time to wait

     * @return true if data is available, false on timeout or error

     */

    bool WaitForData(std::chrono::milliseconds timeout);

    /**

     * Read available data from socket and process complete replies.

     * Dispatches to registered reply handlers.

     * @return true if connection is still open, false if connection was closed

     */

    bool ReceiveAndProcess();

private:

    /** Reference to interrupt object for clean shutdown */

    CThreadInterrupt& m_interrupt;

    /** Socket for the connection */

    std::unique_ptr<Sock> m_sock;

    /** Message being received */

    TorControlReply m_message;

    /** Response handlers */

    std::deque<ReplyHandlerCB> m_reply_handlers;

    /** Buffer for incoming data */

    std::vector<std::byte> m_recv_buffer;

    /** Process complete lines from the receive buffer */

    bool ProcessBuffer();

};

/****** Bitcoin specific TorController implementation ********/

/** Controller that connects to Tor control socket, authenticate, then create

 * and maintain an ephemeral onion service.

 */

class TorController

{

public:

    TorController(const std::string& tor_control_center, const CService& target);

    TorController() : m_conn(m_interrupt) {

        // Used for testing only.

    }

    ~TorController();

    /** Get name of file to store private key in */

    fs::path GetPrivateKeyFile();

    /** Interrupt the controller thread */

    void Interrupt();

    /** Wait for the controller thread to exit */

    void Join();

private:

    CThreadInterrupt m_interrupt;

    std::thread m_thread;

    const std::string m_tor_control_center;

    TorControlConnection m_conn;

    std::string m_private_key;

    std::string m_service_id;

    std::atomic<bool> m_reconnect;

    std::chrono::duration<double> m_reconnect_timeout;

    CService m_service;

    const CService m_target;

    /** Cookie for SAFECOOKIE auth */

    std::vector<uint8_t> m_cookie;

    /** ClientNonce for SAFECOOKIE auth */

    std::vector<uint8_t> m_client_nonce;

    /** Main control thread */

    void ThreadControl();

public:

    /** Callback for GETINFO net/listeners/socks result */

    void get_socks_cb(TorControlConnection& conn, const TorControlReply& reply);

    /** Callback for ADD_ONION result */

    void add_onion_cb(TorControlConnection& conn, const TorControlReply& reply, bool pow_was_enabled);

    /** Callback for AUTHENTICATE result */

    void auth_cb(TorControlConnection& conn, const TorControlReply& reply);

    /** Callback for AUTHCHALLENGE result */

    void authchallenge_cb(TorControlConnection& conn, const TorControlReply& reply);

    /** Callback for PROTOCOLINFO result */

    void protocolinfo_cb(TorControlConnection& conn, const TorControlReply& reply);

    /** Callback after successful connection */

    void connected_cb(TorControlConnection& conn);

    /** Callback after connection lost or failed connection attempt */

    void disconnected_cb(TorControlConnection& conn);

};

#endif // BITCOIN_TORCONTROL_H