src/torcontrol.cpp

   1 // Copyright (c) 2015 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 #include "torcontrol.h"
   6 #include "utilstrencodings.h"
   7 #include "net.h"
   8 #include "util.h"
   9 #include "crypto/hmac_sha256.h"
  10
  11 #include <vector>
  12 #include <deque>
  13 #include <set>
  14 #include <stdlib.h>
  15
  16 #include <boost/function.hpp>
  17 #include <boost/bind.hpp>
  18 #include <boost/signals2/signal.hpp>
  19 #include <boost/foreach.hpp>
  20 #include <boost/algorithm/string/predicate.hpp>
  21 #include <boost/algorithm/string/split.hpp>
  22 #include <boost/algorithm/string/classification.hpp>
  23 #include <boost/algorithm/string/replace.hpp>
  24
  25 #include <event2/bufferevent.h>
  26 #include <event2/buffer.h>
  27 #include <event2/util.h>
  28 #include <event2/event.h>
  29 #include <event2/thread.h>
  30
  31 /** Default control port */
  32 const std::string DEFAULT_TOR_CONTROL = "127.0.0.1:9051";
  33 /** Tor cookie size (from control-spec.txt) */
  34 static const int TOR_COOKIE_SIZE = 32;
  35 /** Size of client/server nonce for SAFECOOKIE */
  36 static const int TOR_NONCE_SIZE = 32;
  37 /** For computing serverHash in SAFECOOKIE */
  38 static const std::string TOR_SAFE_SERVERKEY = "Tor safe cookie authentication server-to-controller hash";
  39 /** For computing clientHash in SAFECOOKIE */
  40 static const std::string TOR_SAFE_CLIENTKEY = "Tor safe cookie authentication controller-to-server hash";
  41 /** Exponential backoff configuration - initial timeout in seconds */
  42 static const float RECONNECT_TIMEOUT_START = 1.0;
  43 /** Exponential backoff configuration - growth factor */
  44 static const float RECONNECT_TIMEOUT_EXP = 1.5;
  45 /** Maximum length for lines received on TorControlConnection.
  46  * tor-control-spec.txt mentions that there is explicitly no limit defined to line length,
  47  * this is belt-and-suspenders sanity limit to prevent memory exhaustion.
  48  */
  49 static const int MAX_LINE_LENGTH = 100000;
  50
  51 /****** Low-level TorControlConnection ********/
  52
  53 /** Reply from Tor, can be single or multi-line */
  54 class TorControlReply
  55 {
  56 public:
  57     TorControlReply() { Clear(); }
  58
  59     int code;
  60     std::vector<std::string> lines;
  61
  62     void Clear()
  63     {
  64         code = 0;
  65         lines.clear();
  66     }
  67 };
  68
  69 /** Low-level handling for Tor control connection.
  70  * Speaks the SMTP-like protocol as defined in torspec/control-spec.txt
  71  */
  72 class TorControlConnection
  73 {
  74 public:
  75     typedef boost::function<void(TorControlConnection&)> ConnectionCB;
  76     typedef boost::function<void(TorControlConnection &,const TorControlReply &)> ReplyHandlerCB;
  77
  78     /** Create a new TorControlConnection.
  79      */
  80     TorControlConnection(struct event_base *base);
  81     ~TorControlConnection();
  82
  83     /**
  84      * Connect to a Tor control port.
  85      * target is address of the form host:port.
  86      * connected is the handler that is called when connection is successfully established.
  87      * disconnected is a handler that is called when the connection is broken.
  88      * Return true on success.
  89      */
  90     bool Connect(const std::string &target, const ConnectionCB& connected, const ConnectionCB& disconnected);
  91
  92     /**
  93      * Disconnect from Tor control port.
  94      */
  95     bool Disconnect();
  96
  97     /** Send a command, register a handler for the reply.
  98      * A trailing CRLF is automatically added.
  99      * Return true on success.
 100      */
 101     bool Command(const std::string &cmd, const ReplyHandlerCB& reply_handler);
 102
 103     /** Response handlers for async replies */
 104     boost::signals2::signal<void(TorControlConnection &,const TorControlReply &)> async_handler;
 105 private:
 106     /** Callback when ready for use */
 107     boost::function<void(TorControlConnection&)> connected;
 108     /** Callback when connection lost */
 109     boost::function<void(TorControlConnection&)> disconnected;
 110     /** Libevent event base */
 111     struct event_base *base;
 112     /** Connection to control socket */
 113     struct bufferevent *b_conn;
 114     /** Message being received */
 115     TorControlReply message;
 116     /** Response handlers */
 117     std::deque<ReplyHandlerCB> reply_handlers;
 118
 119     /** Libevent handlers: internal */
 120     static void readcb(struct bufferevent *bev, void *ctx);
 121     static void eventcb(struct bufferevent *bev, short what, void *ctx);
 122 };
 123
 124 TorControlConnection::TorControlConnection(struct event_base *base):
 125     base(base), b_conn(0)
 126 {
 127 }
 128
 129 TorControlConnection::~TorControlConnection()
 130 {
 131     if (b_conn)
 132         bufferevent_free(b_conn);
 133 }
 134
 135 void TorControlConnection::readcb(struct bufferevent *bev, void *ctx)
 136 {
 137     TorControlConnection *self = (TorControlConnection*)ctx;
 138     struct evbuffer *input = bufferevent_get_input(bev);
 139     size_t n_read_out = 0;
 140     char *line;
 141     assert(input);
 142     //  If there is not a whole line to read, evbuffer_readln returns NULL
 143     while((line = evbuffer_readln(input, &n_read_out, EVBUFFER_EOL_CRLF)) != NULL)
 144     {
 145         std::string s(line, n_read_out);
 146         free(line);
 147         if (s.size() < 4) // Short line
 148             continue;
 149         // <status>(-|+| )<data><CRLF>
 150         self->message.code = atoi(s.substr(0,3));
 151         self->message.lines.push_back(s.substr(4));
 152         char ch = s[3]; // '-','+' or ' '
 153         if (ch == ' ') {
 154             // Final line, dispatch reply and clean up
 155             if (self->message.code >= 600) {
 156                 // Dispatch async notifications to async handler
 157                 // Synchronous and asynchronous messages are never interleaved
 158                 self->async_handler(*self, self->message);
 159             } else {
 160                 if (!self->reply_handlers.empty()) {
 161                     // Invoke reply handler with message
 162                     self->reply_handlers.front()(*self, self->message);
 163                     self->reply_handlers.pop_front();
 164                 } else {
 165                     LogPrint("tor", "tor: Received unexpected sync reply %i\n", self->message.code);
 166                 }
 167             }
 168             self->message.Clear();
 169         }
 170     }
 171     //  Check for size of buffer - protect against memory exhaustion with very long lines
 172     //  Do this after evbuffer_readln to make sure all full lines have been
 173     //  removed from the buffer. Everything left is an incomplete line.
 174     if (evbuffer_get_length(input) > MAX_LINE_LENGTH) {
 175         LogPrintf("tor: Disconnecting because MAX_LINE_LENGTH exceeded\n");
 176         self->Disconnect();
 177     }
 178 }
 179
 180 void TorControlConnection::eventcb(struct bufferevent *bev, short what, void *ctx)
 181 {
 182     TorControlConnection *self = (TorControlConnection*)ctx;
 183     if (what & BEV_EVENT_CONNECTED) {
 184         LogPrint("tor", "tor: Successfully connected!\n");
 185         self->connected(*self);
 186     } else if (what & (BEV_EVENT_EOF|BEV_EVENT_ERROR)) {
 187         if (what & BEV_EVENT_ERROR)
 188             LogPrint("tor", "tor: Error connecting to Tor control socket\n");
 189         else
 190             LogPrint("tor", "tor: End of stream\n");
 191         self->Disconnect();
 192         self->disconnected(*self);
 193     }
 194 }
 195
 196 bool TorControlConnection::Connect(const std::string &target, const ConnectionCB& connected, const ConnectionCB& disconnected)
 197 {
 198     if (b_conn)
 199         Disconnect();
 200     // Parse target address:port
 201     struct sockaddr_storage connect_to_addr;
 202     int connect_to_addrlen = sizeof(connect_to_addr);
 203     if (evutil_parse_sockaddr_port(target.c_str(),
 204         (struct sockaddr*)&connect_to_addr, &connect_to_addrlen)<0) {
 205         LogPrintf("tor: Error parsing socket address %s\n", target);
 206         return false;
 207     }
 208
 209     // Create a new socket, set up callbacks and enable notification bits
 210     b_conn = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE);
 211     if (!b_conn)
 212         return false;
 213     bufferevent_setcb(b_conn, TorControlConnection::readcb, NULL, TorControlConnection::eventcb, this);
 214     bufferevent_enable(b_conn, EV_READ|EV_WRITE);
 215     this->connected = connected;
 216     this->disconnected = disconnected;
 217
 218     // Finally, connect to target
 219     if (bufferevent_socket_connect(b_conn, (struct sockaddr*)&connect_to_addr, connect_to_addrlen) < 0) {
 220         LogPrintf("tor: Error connecting to address %s\n", target);
 221         return false;
 222     }
 223     return true;
 224 }
 225
 226 bool TorControlConnection::Disconnect()
 227 {
 228     if (b_conn)
 229         bufferevent_free(b_conn);
 230     b_conn = 0;
 231     return true;
 232 }
 233
 234 bool TorControlConnection::Command(const std::string &cmd, const ReplyHandlerCB& reply_handler)
 235 {
 236     if (!b_conn)
 237         return false;
 238     struct evbuffer *buf = bufferevent_get_output(b_conn);
 239     if (!buf)
 240         return false;
 241     evbuffer_add(buf, cmd.data(), cmd.size());
 242     evbuffer_add(buf, "\r\n", 2);
 243     reply_handlers.push_back(reply_handler);
 244     return true;
 245 }
 246
 247 /****** General parsing utilities ********/
 248
 249 /* Split reply line in the form 'AUTH METHODS=...' into a type
 250  * 'AUTH' and arguments 'METHODS=...'.
 251  */
 252 static std::pair<std::string,std::string> SplitTorReplyLine(const std::string &s)
 253 {
 254     size_t ptr=0;
 255     std::string type;
 256     while (ptr < s.size() && s[ptr] != ' ') {
 257         type.push_back(s[ptr]);
 258         ++ptr;
 259     }
 260     if (ptr < s.size())
 261         ++ptr; // skip ' '
 262     return make_pair(type, s.substr(ptr));
 263 }
 264
 265 /** Parse reply arguments in the form 'METHODS=COOKIE,SAFECOOKIE COOKIEFILE=".../control_auth_cookie"'.
 266  */
 267 static std::map<std::string,std::string> ParseTorReplyMapping(const std::string &s)
 268 {
 269     std::map<std::string,std::string> mapping;
 270     size_t ptr=0;
 271     while (ptr < s.size()) {
 272         std::string key, value;
 273         while (ptr < s.size() && s[ptr] != '=') {
 274             key.push_back(s[ptr]);
 275             ++ptr;
 276         }
 277         if (ptr == s.size()) // unexpected end of line
 278             return std::map<std::string,std::string>();
 279         ++ptr; // skip '='
 280         if (ptr < s.size() && s[ptr] == '"') { // Quoted string
 281             ++ptr; // skip '='
 282             bool escape_next = false;
 283             while (ptr < s.size() && (!escape_next && s[ptr] != '"')) {
 284                 escape_next = (s[ptr] == '\\');
 285                 value.push_back(s[ptr]);
 286                 ++ptr;
 287             }
 288             if (ptr == s.size()) // unexpected end of line
 289                 return std::map<std::string,std::string>();
 290             ++ptr; // skip closing '"'
 291             /* TODO: unescape value - according to the spec this depends on the
 292              * context, some strings use C-LogPrintf style escape codes, some
 293              * don't. So may be better handled at the call site.
 294              */
 295         } else { // Unquoted value. Note that values can contain '=' at will, just no spaces
 296             while (ptr < s.size() && s[ptr] != ' ') {
 297                 value.push_back(s[ptr]);
 298                 ++ptr;
 299             }
 300         }
 301         if (ptr < s.size() && s[ptr] == ' ')
 302             ++ptr; // skip ' ' after key=value
 303         mapping[key] = value;
 304     }
 305     return mapping;
 306 }
 307
 308 /** Read full contents of a file and return them in a std::string.
 309  * Returns a pair <status, string>.
 310  * If an error occurred, status will be false, otherwise status will be true and the data will be returned in string.
 311  *
 312  * @param maxsize Puts a maximum size limit on the file that is read. If the file is larger than this, truncated data
 313  *         (with len > maxsize) will be returned.
 314  */
 315 static std::pair<bool,std::string> ReadBinaryFile(const std::string &filename, size_t maxsize=std::numeric_limits<size_t>::max())
 316 {
 317     FILE *f = fopen(filename.c_str(), "rb");
 318     if (f == NULL)
 319         return std::make_pair(false,"");
 320     std::string retval;
 321     char buffer[128];
 322     size_t n;
 323     while ((n=fread(buffer, 1, sizeof(buffer), f)) > 0) {
 324         retval.append(buffer, buffer+n);
 325         if (retval.size() > maxsize)
 326             break;
 327     }
 328     fclose(f);
 329     return std::make_pair(true,retval);
 330 }
 331
 332 /** Write contents of std::string to a file.
 333  * @return true on success.
 334  */
 335 static bool WriteBinaryFile(const std::string &filename, const std::string &data)
 336 {
 337     FILE *f = fopen(filename.c_str(), "wb");
 338     if (f == NULL)
 339         return false;
 340     if (fwrite(data.data(), 1, data.size(), f) != data.size()) {
 341         fclose(f);
 342         return false;
 343     }
 344     fclose(f);
 345     return true;
 346 }
 347
 348 /****** Bitcoin specific TorController implementation ********/
 349
 350 /** Controller that connects to Tor control socket, authenticate, then create
 351  * and maintain a ephemeral hidden service.
 352  */
 353 class TorController
 354 {
 355 public:
 356     TorController(struct event_base* base, const std::string& target);
 357     ~TorController();
 358
 359     /** Get name fo file to store private key in */
 360     std::string GetPrivateKeyFile();
 361
 362     /** Reconnect, after getting disconnected */
 363     void Reconnect();
 364 private:
 365     struct event_base* base;
 366     std::string target;
 367     TorControlConnection conn;
 368     std::string private_key;
 369     std::string service_id;
 370     bool reconnect;
 371     struct event *reconnect_ev;
 372     float reconnect_timeout;
 373     CService service;
 374     /** Cooie for SAFECOOKIE auth */
 375     std::vector<uint8_t> cookie;
 376     /** ClientNonce for SAFECOOKIE auth */
 377     std::vector<uint8_t> clientNonce;
 378
 379     /** Callback for ADD_ONION result */
 380     void add_onion_cb(TorControlConnection& conn, const TorControlReply& reply);
 381     /** Callback for AUTHENTICATE result */
 382     void auth_cb(TorControlConnection& conn, const TorControlReply& reply);
 383     /** Callback for AUTHCHALLENGE result */
 384     void authchallenge_cb(TorControlConnection& conn, const TorControlReply& reply);
 385     /** Callback for PROTOCOLINFO result */
 386     void protocolinfo_cb(TorControlConnection& conn, const TorControlReply& reply);
 387     /** Callback after successful connection */
 388     void connected_cb(TorControlConnection& conn);
 389     /** Callback after connection lost or failed connection attempt */
 390     void disconnected_cb(TorControlConnection& conn);
 391
 392     /** Callback for reconnect timer */
 393     static void reconnect_cb(evutil_socket_t fd, short what, void *arg);
 394 };
 395
 396 TorController::TorController(struct event_base* baseIn, const std::string& target):
 397     base(baseIn),
 398     target(target), conn(base), reconnect(true), reconnect_ev(0),
 399     reconnect_timeout(RECONNECT_TIMEOUT_START)
 400 {
 401     reconnect_ev = event_new(base, -1, 0, reconnect_cb, this);
 402     if (!reconnect_ev)
 403         LogPrintf("tor: Failed to create event for reconnection: out of memory?\n");
 404     // Start connection attempts immediately
 405     if (!conn.Connect(target, boost::bind(&TorController::connected_cb, this, _1),
 406          boost::bind(&TorController::disconnected_cb, this, _1) )) {
 407         LogPrintf("tor: Initiating connection to Tor control port %s failed\n", target);
 408     }
 409     // Read service private key if cached
 410     std::pair<bool,std::string> pkf = ReadBinaryFile(GetPrivateKeyFile());
 411     if (pkf.first) {
 412         LogPrint("tor", "tor: Reading cached private key from %s\n", GetPrivateKeyFile());
 413         private_key = pkf.second;
 414     }
 415 }
 416
 417 TorController::~TorController()
 418 {
 419     if (reconnect_ev) {
 420         event_free(reconnect_ev);
 421         reconnect_ev = 0;
 422     }
 423     if (service.IsValid()) {
 424         RemoveLocal(service);
 425     }
 426 }
 427
 428 void TorController::add_onion_cb(TorControlConnection& conn, const TorControlReply& reply)
 429 {
 430     if (reply.code == 250) {
 431         LogPrint("tor", "tor: ADD_ONION successful\n");
 432         BOOST_FOREACH(const std::string &s, reply.lines) {
 433             std::map<std::string,std::string> m = ParseTorReplyMapping(s);
 434             std::map<std::string,std::string>::iterator i;
 435             if ((i = m.find("ServiceID")) != m.end())
 436                 service_id = i->second;
 437             if ((i = m.find("PrivateKey")) != m.end())
 438                 private_key = i->second;
 439         }
 440
 441         service = CService(service_id+".onion", GetListenPort());
 442         LogPrintf("tor: Got service ID %s, advertising service %s\n", service_id, service.ToString());
 443         if (WriteBinaryFile(GetPrivateKeyFile(), private_key)) {
 444             LogPrint("tor", "tor: Cached service private key to %s\n", GetPrivateKeyFile());
 445         } else {
 446             LogPrintf("tor: Error writing service private key to %s\n", GetPrivateKeyFile());
 447         }
 448         AddLocal(service, LOCAL_MANUAL);
 449         // ... onion requested - keep connection open
 450     } else if (reply.code == 510) { // 510 Unrecognized command
 451         LogPrintf("tor: Add onion failed with unrecognized command (You probably need to upgrade Tor)\n");
 452     } else {
 453         LogPrintf("tor: Add onion failed; error code %d\n", reply.code);
 454     }
 455 }
 456
 457 void TorController::auth_cb(TorControlConnection& conn, const TorControlReply& reply)
 458 {
 459     if (reply.code == 250) {
 460         LogPrint("tor", "tor: Authentication successful\n");
 461
 462         // Now that we know Tor is running setup the proxy for onion addresses
 463         // if -onion isn't set to something else.
 464         if (GetArg("-onion", "") == "") {
 465             proxyType addrOnion = proxyType(CService("127.0.0.1", 9050), true);
 466             SetProxy(NET_TOR, addrOnion);
 467             SetLimited(NET_TOR, false);
 468         }
 469
 470         // Finally - now create the service
 471         if (private_key.empty()) // No private key, generate one
 472             private_key = "NEW:BEST";
 473         // Request hidden service, redirect port.
 474         // Note that the 'virtual' port doesn't have to be the same as our internal port, but this is just a convenient
 475         // choice.  TODO; refactor the shutdown sequence some day.
 476         conn.Command(strprintf("ADD_ONION %s Port=%i,127.0.0.1:%i", private_key, GetListenPort(), GetListenPort()),
 477             boost::bind(&TorController::add_onion_cb, this, _1, _2));
 478     } else {
 479         LogPrintf("tor: Authentication failed\n");
 480     }
 481 }
 482
 483 /** Compute Tor SAFECOOKIE response.
 484  *
 485  *    ServerHash is computed as:
 486  *      HMAC-SHA256("Tor safe cookie authentication server-to-controller hash",
 487  *                  CookieString | ClientNonce | ServerNonce)
 488  *    (with the HMAC key as its first argument)
 489  *
 490  *    After a controller sends a successful AUTHCHALLENGE command, the
 491  *    next command sent on the connection must be an AUTHENTICATE command,
 492  *    and the only authentication string which that AUTHENTICATE command
 493  *    will accept is:
 494  *
 495  *      HMAC-SHA256("Tor safe cookie authentication controller-to-server hash",
 496  *                  CookieString | ClientNonce | ServerNonce)
 497  *
 498  */
 499 static std::vector<uint8_t> ComputeResponse(const std::string &key, const std::vector<uint8_t> &cookie,  const std::vector<uint8_t> &clientNonce, const std::vector<uint8_t> &serverNonce)
 500 {
 501     CHMAC_SHA256 computeHash((const uint8_t*)key.data(), key.size());
 502     std::vector<uint8_t> computedHash(CHMAC_SHA256::OUTPUT_SIZE, 0);
 503     computeHash.Write(begin_ptr(cookie), cookie.size());
 504     computeHash.Write(begin_ptr(clientNonce), clientNonce.size());
 505     computeHash.Write(begin_ptr(serverNonce), serverNonce.size());
 506     computeHash.Finalize(begin_ptr(computedHash));
 507     return computedHash;
 508 }
 509
 510 void TorController::authchallenge_cb(TorControlConnection& conn, const TorControlReply& reply)
 511 {
 512     if (reply.code == 250) {
 513         LogPrint("tor", "tor: SAFECOOKIE authentication challenge successful\n");
 514         std::pair<std::string,std::string> l = SplitTorReplyLine(reply.lines[0]);
 515         if (l.first == "AUTHCHALLENGE") {
 516             std::map<std::string,std::string> m = ParseTorReplyMapping(l.second);
 517             std::vector<uint8_t> serverHash = ParseHex(m["SERVERHASH"]);
 518             std::vector<uint8_t> serverNonce = ParseHex(m["SERVERNONCE"]);
 519             LogPrint("tor", "tor: AUTHCHALLENGE ServerHash %s ServerNonce %s\n", HexStr(serverHash), HexStr(serverNonce));
 520             if (serverNonce.size() != 32) {
 521                 LogPrintf("tor: ServerNonce is not 32 bytes, as required by spec\n");
 522                 return;
 523             }
 524
 525             std::vector<uint8_t> computedServerHash = ComputeResponse(TOR_SAFE_SERVERKEY, cookie, clientNonce, serverNonce);
 526             if (computedServerHash != serverHash) {
 527                 LogPrintf("tor: ServerHash %s does not match expected ServerHash %s\n", HexStr(serverHash), HexStr(computedServerHash));
 528                 return;
 529             }
 530
 531             std::vector<uint8_t> computedClientHash = ComputeResponse(TOR_SAFE_CLIENTKEY, cookie, clientNonce, serverNonce);
 532             conn.Command("AUTHENTICATE " + HexStr(computedClientHash), boost::bind(&TorController::auth_cb, this, _1, _2));
 533         } else {
 534             LogPrintf("tor: Invalid reply to AUTHCHALLENGE\n");
 535         }
 536     } else {
 537         LogPrintf("tor: SAFECOOKIE authentication challenge failed\n");
 538     }
 539 }
 540
 541 void TorController::protocolinfo_cb(TorControlConnection& conn, const TorControlReply& reply)
 542 {
 543     if (reply.code == 250) {
 544         std::set<std::string> methods;
 545         std::string cookiefile;
 546         /*
 547          * 250-AUTH METHODS=COOKIE,SAFECOOKIE COOKIEFILE="/home/x/.tor/control_auth_cookie"
 548          * 250-AUTH METHODS=NULL
 549          * 250-AUTH METHODS=HASHEDPASSWORD
 550          */
 551         BOOST_FOREACH(const std::string &s, reply.lines) {
 552             std::pair<std::string,std::string> l = SplitTorReplyLine(s);
 553             if (l.first == "AUTH") {
 554                 std::map<std::string,std::string> m = ParseTorReplyMapping(l.second);
 555                 std::map<std::string,std::string>::iterator i;
 556                 if ((i = m.find("METHODS")) != m.end())
 557                     boost::split(methods, i->second, boost::is_any_of(","));
 558                 if ((i = m.find("COOKIEFILE")) != m.end())
 559                     cookiefile = i->second;
 560             } else if (l.first == "VERSION") {
 561                 std::map<std::string,std::string> m = ParseTorReplyMapping(l.second);
 562                 std::map<std::string,std::string>::iterator i;
 563                 if ((i = m.find("Tor")) != m.end()) {
 564                     LogPrint("tor", "tor: Connected to Tor version %s\n", i->second);
 565                 }
 566             }
 567         }
 568         BOOST_FOREACH(const std::string &s, methods) {
 569             LogPrint("tor", "tor: Supported authentication method: %s\n", s);
 570         }
 571         // Prefer NULL, otherwise SAFECOOKIE. If a password is provided, use HASHEDPASSWORD
 572         /* Authentication:
 573          *   cookie:   hex-encoded ~/.tor/control_auth_cookie
 574          *   password: "password"
 575          */
 576         std::string torpassword = GetArg("-torpassword", "");
 577         if (methods.count("NULL")) {
 578             LogPrint("tor", "tor: Using NULL authentication\n");
 579             conn.Command("AUTHENTICATE", boost::bind(&TorController::auth_cb, this, _1, _2));
 580         } else if (methods.count("SAFECOOKIE")) {
 581             // Cookie: hexdump -e '32/1 "%02x""\n"'  ~/.tor/control_auth_cookie
 582             LogPrint("tor", "tor: Using SAFECOOKIE authentication, reading cookie authentication from %s\n", cookiefile);
 583             std::pair<bool,std::string> status_cookie = ReadBinaryFile(cookiefile, TOR_COOKIE_SIZE);
 584             if (status_cookie.first && status_cookie.second.size() == TOR_COOKIE_SIZE) {
 585                 // conn.Command("AUTHENTICATE " + HexStr(status_cookie.second), boost::bind(&TorController::auth_cb, this, _1, _2));
 586                 cookie = std::vector<uint8_t>(status_cookie.second.begin(), status_cookie.second.end());
 587                 clientNonce = std::vector<uint8_t>(TOR_NONCE_SIZE, 0);
 588                 GetRandBytes(&clientNonce[0], TOR_NONCE_SIZE);
 589                 conn.Command("AUTHCHALLENGE SAFECOOKIE " + HexStr(clientNonce), boost::bind(&TorController::authchallenge_cb, this, _1, _2));
 590             } else {
 591                 if (status_cookie.first) {
 592                     LogPrintf("tor: Authentication cookie %s is not exactly %i bytes, as is required by the spec\n", cookiefile, TOR_COOKIE_SIZE);
 593                 } else {
 594                     LogPrintf("tor: Authentication cookie %s could not be opened (check permissions)\n", cookiefile);
 595                 }
 596             }
 597         } else if (methods.count("HASHEDPASSWORD")) {
 598             if (!torpassword.empty()) {
 599                 LogPrint("tor", "tor: Using HASHEDPASSWORD authentication\n");
 600                 boost::replace_all(torpassword, "\"", "\\\"");
 601                 conn.Command("AUTHENTICATE \"" + torpassword + "\"", boost::bind(&TorController::auth_cb, this, _1, _2));
 602             } else {
 603                 LogPrintf("tor: Password authentication required, but no password provided with -torpassword\n");
 604             }
 605         } else {
 606             LogPrintf("tor: No supported authentication method\n");
 607         }
 608     } else {
 609         LogPrintf("tor: Requesting protocol info failed\n");
 610     }
 611 }
 612
 613 void TorController::connected_cb(TorControlConnection& conn)
 614 {
 615     reconnect_timeout = RECONNECT_TIMEOUT_START;
 616     // First send a PROTOCOLINFO command to figure out what authentication is expected
 617     if (!conn.Command("PROTOCOLINFO 1", boost::bind(&TorController::protocolinfo_cb, this, _1, _2)))
 618         LogPrintf("tor: Error sending initial protocolinfo command\n");
 619 }
 620
 621 void TorController::disconnected_cb(TorControlConnection& conn)
 622 {
 623     // Stop advertising service when disconnected
 624     if (service.IsValid())
 625         RemoveLocal(service);
 626     service = CService();
 627     if (!reconnect)
 628         return;
 629
 630     LogPrint("tor", "tor: Not connected to Tor control port %s, trying to reconnect\n", target);
 631
 632     // Single-shot timer for reconnect. Use exponential backoff.
 633     struct timeval time = MillisToTimeval(int64_t(reconnect_timeout * 1000.0));
 634     if (reconnect_ev)
 635         event_add(reconnect_ev, &time);
 636     reconnect_timeout *= RECONNECT_TIMEOUT_EXP;
 637 }
 638
 639 void TorController::Reconnect()
 640 {
 641     /* Try to reconnect and reestablish if we get booted - for example, Tor
 642      * may be restarting.
 643      */
 644     if (!conn.Connect(target, boost::bind(&TorController::connected_cb, this, _1),
 645          boost::bind(&TorController::disconnected_cb, this, _1) )) {
 646         LogPrintf("tor: Re-initiating connection to Tor control port %s failed\n", target);
 647     }
 648 }
 649
 650 std::string TorController::GetPrivateKeyFile()
 651 {
 652     return (GetDataDir() / "onion_private_key").string();
 653 }
 654
 655 void TorController::reconnect_cb(evutil_socket_t fd, short what, void *arg)
 656 {
 657     TorController *self = (TorController*)arg;
 658     self->Reconnect();
 659 }
 660
 661 /****** Thread ********/
 662 struct event_base *base;
 663 boost::thread torControlThread;
 664
 665 static void TorControlThread()
 666 {
 667     TorController ctrl(base, GetArg("-torcontrol", DEFAULT_TOR_CONTROL));
 668
 669     event_base_dispatch(base);
 670 }
 671
 672 void StartTorControl(boost::thread_group& threadGroup, CScheduler& scheduler)
 673 {
 674     assert(!base);
 675 #ifdef WIN32
 676     evthread_use_windows_threads();
 677 #else
 678     evthread_use_pthreads();
 679 #endif
 680     base = event_base_new();
 681     if (!base) {
 682         LogPrintf("tor: Unable to create event_base\n");
 683         return;
 684     }
 685
 686     torControlThread = boost::thread(boost::bind(&TraceThread<void (*)()>, "torcontrol", &TorControlThread));
 687 }
 688
 689 void InterruptTorControl()
 690 {
 691     if (base) {
 692         LogPrintf("tor: Thread interrupt\n");
 693         event_base_loopbreak(base);
 694     }
 695 }
 696
 697 void StopTorControl()
 698 {
 699     if (base) {
 700         torControlThread.join();
 701         event_base_free(base);
 702         base = 0;
 703     }
 704 }
 705