Line data    Source code

       1             : // Copyright (c) 2015-2021 The Bitcoin Core developers
       2             : // Distributed under the MIT software license, see the accompanying
       3             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4             : 
       5             : /**
       6             :  * Functionality for communicating with Tor.
       7             :  */
       8             : #ifndef BITCOIN_TORCONTROL_H
       9             : #define BITCOIN_TORCONTROL_H
      10             : 
      11             : #include <netaddress.h>
      12             : #include <util/fs.h>
      13             : 
      14             : #include <event2/util.h>
      15             : 
      16             : #include <cstdint>
      17             : #include <deque>
      18             : #include <functional>
      19             : #include <string>
      20             : #include <vector>
      21             : 
      22             : constexpr int DEFAULT_TOR_CONTROL_PORT = 9051;
      23             : extern const std::string DEFAULT_TOR_CONTROL;
      24             : static const bool DEFAULT_LISTEN_ONION = true;
      25             : 
      26             : void StartTorControl(CService onion_service_target);
      27             : void InterruptTorControl();
      28             : void StopTorControl();
      29             : 
      30             : CService DefaultOnionServiceTarget();
      31             : 
      32             : /** Reply from Tor, can be single or multi-line */
      33             : class TorControlReply
      34             : {
      35             : public:
      36           0 :     TorControlReply() { Clear(); }
      37             : 
      38             :     int code;
      39             :     std::vector<std::string> lines;
      40             : 
      41           0 :     void Clear()
      42             :     {
      43           0 :         code = 0;
      44           0 :         lines.clear();
      45           0 :     }
      46             : };
      47             : 
      48             : /** Low-level handling for Tor control connection.
      49             :  * Speaks the SMTP-like protocol as defined in torspec/control-spec.txt
      50             :  */
      51             : class TorControlConnection
      52             : {
      53             : public:
      54             :     typedef std::function<void(TorControlConnection&)> ConnectionCB;
      55             :     typedef std::function<void(TorControlConnection &,const TorControlReply &)> ReplyHandlerCB;
      56             : 
      57             :     /** Create a new TorControlConnection.
      58             :      */
      59             :     explicit TorControlConnection(struct event_base *base);
      60             :     ~TorControlConnection();
      61             : 
      62             :     /**
      63             :      * Connect to a Tor control port.
      64             :      * tor_control_center is address of the form host:port.
      65             :      * connected is the handler that is called when connection is successfully established.
      66             :      * disconnected is a handler that is called when the connection is broken.
      67             :      * Return true on success.
      68             :      */
      69             :     bool Connect(const std::string& tor_control_center, const ConnectionCB& connected, const ConnectionCB& disconnected);
      70             : 
      71             :     /**
      72             :      * Disconnect from Tor control port.
      73             :      */
      74             :     void Disconnect();
      75             : 
      76             :     /** Send a command, register a handler for the reply.
      77             :      * A trailing CRLF is automatically added.
      78             :      * Return true on success.
      79             :      */
      80             :     bool Command(const std::string &cmd, const ReplyHandlerCB& reply_handler);
      81             : 
      82             : private:
      83             :     /** Callback when ready for use */
      84             :     std::function<void(TorControlConnection&)> connected;
      85             :     /** Callback when connection lost */
      86             :     std::function<void(TorControlConnection&)> disconnected;
      87             :     /** Libevent event base */
      88             :     struct event_base *base;
      89             :     /** Connection to control socket */
      90             :     struct bufferevent* b_conn{nullptr};
      91             :     /** Message being received */
      92             :     TorControlReply message;
      93             :     /** Response handlers */
      94             :     std::deque<ReplyHandlerCB> reply_handlers;
      95             : 
      96             :     /** Libevent handlers: internal */
      97             :     static void readcb(struct bufferevent *bev, void *ctx);
      98             :     static void eventcb(struct bufferevent *bev, short what, void *ctx);
      99             : };
     100             : 
     101             : /****** Bitcoin specific TorController implementation ********/
     102             : 
     103             : /** Controller that connects to Tor control socket, authenticate, then create
     104             :  * and maintain an ephemeral onion service.
     105             :  */
     106             : class TorController
     107             : {
     108             : public:
     109             :     TorController(struct event_base* base, const std::string& tor_control_center, const CService& target);
     110           0 :     TorController() : conn{nullptr} {
     111             :         // Used for testing only.
     112           0 :     }
     113             :     ~TorController();
     114             : 
     115             :     /** Get name of file to store private key in */
     116             :     fs::path GetPrivateKeyFile();
     117             : 
     118             :     /** Reconnect, after getting disconnected */
     119             :     void Reconnect();
     120             : private:
     121             :     struct event_base* base;
     122             :     const std::string m_tor_control_center;
     123             :     TorControlConnection conn;
     124             :     std::string private_key;
     125             :     std::string service_id;
     126             :     bool reconnect;
     127           0 :     struct event *reconnect_ev = nullptr;
     128             :     float reconnect_timeout;
     129             :     CService service;
     130             :     const CService m_target;
     131             :     /** Cookie for SAFECOOKIE auth */
     132             :     std::vector<uint8_t> cookie;
     133             :     /** ClientNonce for SAFECOOKIE auth */
     134             :     std::vector<uint8_t> clientNonce;
     135             : 
     136             : public:
     137             :     /** Callback for GETINFO net/listeners/socks result */
     138             :     void get_socks_cb(TorControlConnection& conn, const TorControlReply& reply);
     139             :     /** Callback for ADD_ONION result */
     140             :     void add_onion_cb(TorControlConnection& conn, const TorControlReply& reply);
     141             :     /** Callback for AUTHENTICATE result */
     142             :     void auth_cb(TorControlConnection& conn, const TorControlReply& reply);
     143             :     /** Callback for AUTHCHALLENGE result */
     144             :     void authchallenge_cb(TorControlConnection& conn, const TorControlReply& reply);
     145             :     /** Callback for PROTOCOLINFO result */
     146             :     void protocolinfo_cb(TorControlConnection& conn, const TorControlReply& reply);
     147             :     /** Callback after successful connection */
     148             :     void connected_cb(TorControlConnection& conn);
     149             :     /** Callback after connection lost or failed connection attempt */
     150             :     void disconnected_cb(TorControlConnection& conn);
     151             : 
     152             :     /** Callback for reconnect timer */
     153             :     static void reconnect_cb(evutil_socket_t fd, short what, void *arg);
     154             : };
     155             : 
     156             : #endif // BITCOIN_TORCONTROL_H