Line data Source code
1 : // Copyright (c) 2015-2019 The Bitcoin Core developers
2 : // Copyright (c) 2017 The Zcash developers
3 : // Distributed under the MIT software license, see the accompanying
4 : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5 :
6 : #include <chainparams.h>
7 : #include <torcontrol.h>
8 : #include <util/strencodings.h>
9 : #include <netbase.h>
10 : #include <net.h>
11 : #include <util/system.h>
12 : #include <crypto/hmac_sha256.h>
13 :
14 : #include <vector>
15 : #include <deque>
16 : #include <set>
17 : #include <stdlib.h>
18 :
19 : #include <boost/signals2/signal.hpp>
20 : #include <boost/algorithm/string/split.hpp>
21 : #include <boost/algorithm/string/classification.hpp>
22 : #include <boost/algorithm/string/replace.hpp>
23 :
24 : #include <event2/bufferevent.h>
25 : #include <event2/buffer.h>
26 : #include <event2/util.h>
27 : #include <event2/event.h>
28 : #include <event2/thread.h>
29 :
30 : /** Default control port */
31 640 : const std::string DEFAULT_TOR_CONTROL = "127.0.0.1:9051";
32 : /** Tor cookie size (from control-spec.txt) */
33 : static const int TOR_COOKIE_SIZE = 32;
34 : /** Size of client/server nonce for SAFECOOKIE */
35 : static const int TOR_NONCE_SIZE = 32;
36 : /** For computing serverHash in SAFECOOKIE */
37 640 : static const std::string TOR_SAFE_SERVERKEY = "Tor safe cookie authentication server-to-controller hash";
38 : /** For computing clientHash in SAFECOOKIE */
39 640 : static const std::string TOR_SAFE_CLIENTKEY = "Tor safe cookie authentication controller-to-server hash";
40 : /** Exponential backoff configuration - initial timeout in seconds */
41 : static const float RECONNECT_TIMEOUT_START = 1.0;
42 : /** Exponential backoff configuration - growth factor */
43 : static const float RECONNECT_TIMEOUT_EXP = 1.5;
44 : /** Maximum length for lines received on TorControlConnection.
45 : * tor-control-spec.txt mentions that there is explicitly no limit defined to line length,
46 : * this is belt-and-suspenders sanity limit to prevent memory exhaustion.
47 : */
48 : static const int MAX_LINE_LENGTH = 100000;
49 :
50 : /****** Low-level TorControlConnection ********/
51 :
52 : /** Reply from Tor, can be single or multi-line */
53 0 : class TorControlReply
54 : {
55 : public:
56 0 : TorControlReply() { Clear(); }
57 :
58 : int code;
59 : std::vector<std::string> lines;
60 :
61 0 : void Clear()
62 : {
63 0 : code = 0;
64 0 : lines.clear();
65 0 : }
66 : };
67 :
68 : /** Low-level handling for Tor control connection.
69 : * Speaks the SMTP-like protocol as defined in torspec/control-spec.txt
70 : */
71 : class TorControlConnection
72 : {
73 : public:
74 : typedef std::function<void(TorControlConnection&)> ConnectionCB;
75 : typedef std::function<void(TorControlConnection &,const TorControlReply &)> ReplyHandlerCB;
76 :
77 : /** Create a new TorControlConnection.
78 : */
79 : explicit TorControlConnection(struct event_base *base);
80 : ~TorControlConnection();
81 :
82 : /**
83 : * Connect to a Tor control port.
84 : * target is address of the form host:port.
85 : * connected is the handler that is called when connection is successfully established.
86 : * disconnected is a handler that is called when the connection is broken.
87 : * Return true on success.
88 : */
89 : bool Connect(const std::string &target, const ConnectionCB& connected, const ConnectionCB& disconnected);
90 :
91 : /**
92 : * Disconnect from Tor control port.
93 : */
94 : void Disconnect();
95 :
96 : /** Send a command, register a handler for the reply.
97 : * A trailing CRLF is automatically added.
98 : * Return true on success.
99 : */
100 : bool Command(const std::string &cmd, const ReplyHandlerCB& reply_handler);
101 :
102 : /** Response handlers for async replies */
103 : boost::signals2::signal<void(TorControlConnection &,const TorControlReply &)> async_handler;
104 : private:
105 : /** Callback when ready for use */
106 : std::function<void(TorControlConnection&)> connected;
107 : /** Callback when connection lost */
108 : std::function<void(TorControlConnection&)> disconnected;
109 : /** Libevent event base */
110 : struct event_base *base;
111 : /** Connection to control socket */
112 : struct bufferevent *b_conn;
113 : /** Message being received */
114 : TorControlReply message;
115 : /** Response handlers */
116 : std::deque<ReplyHandlerCB> reply_handlers;
117 :
118 : /** Libevent handlers: internal */
119 : static void readcb(struct bufferevent *bev, void *ctx);
120 : static void eventcb(struct bufferevent *bev, short what, void *ctx);
121 : };
122 :
123 0 : TorControlConnection::TorControlConnection(struct event_base *_base):
124 0 : base(_base), b_conn(nullptr)
125 0 : {
126 0 : }
127 :
128 0 : TorControlConnection::~TorControlConnection()
129 0 : {
130 0 : if (b_conn)
131 0 : bufferevent_free(b_conn);
132 0 : }
133 :
134 0 : void TorControlConnection::readcb(struct bufferevent *bev, void *ctx)
135 : {
136 0 : TorControlConnection *self = static_cast<TorControlConnection*>(ctx);
137 0 : struct evbuffer *input = bufferevent_get_input(bev);
138 0 : size_t n_read_out = 0;
139 : char *line;
140 0 : assert(input);
141 : // If there is not a whole line to read, evbuffer_readln returns nullptr
142 0 : while((line = evbuffer_readln(input, &n_read_out, EVBUFFER_EOL_CRLF)) != nullptr)
143 : {
144 0 : std::string s(line, n_read_out);
145 0 : free(line);
146 0 : if (s.size() < 4) // Short line
147 0 : continue;
148 : // <status>(-|+| )<data><CRLF>
149 0 : self->message.code = atoi(s.substr(0,3));
150 0 : self->message.lines.push_back(s.substr(4));
151 0 : char ch = s[3]; // '-','+' or ' '
152 0 : if (ch == ' ') {
153 : // Final line, dispatch reply and clean up
154 0 : if (self->message.code >= 600) {
155 : // Dispatch async notifications to async handler
156 : // Synchronous and asynchronous messages are never interleaved
157 0 : self->async_handler(*self, self->message);
158 : } else {
159 0 : if (!self->reply_handlers.empty()) {
160 : // Invoke reply handler with message
161 0 : self->reply_handlers.front()(*self, self->message);
162 0 : self->reply_handlers.pop_front();
163 : } else {
164 0 : LogPrint(BCLog::TOR, "tor: Received unexpected sync reply %i\n", self->message.code);
165 : }
166 : }
167 0 : self->message.Clear();
168 0 : }
169 0 : }
170 : // Check for size of buffer - protect against memory exhaustion with very long lines
171 : // Do this after evbuffer_readln to make sure all full lines have been
172 : // removed from the buffer. Everything left is an incomplete line.
173 0 : if (evbuffer_get_length(input) > MAX_LINE_LENGTH) {
174 0 : LogPrintf("tor: Disconnecting because MAX_LINE_LENGTH exceeded\n");
175 0 : self->Disconnect();
176 0 : }
177 0 : }
178 :
179 0 : void TorControlConnection::eventcb(struct bufferevent *bev, short what, void *ctx)
180 : {
181 0 : TorControlConnection *self = static_cast<TorControlConnection*>(ctx);
182 0 : if (what & BEV_EVENT_CONNECTED) {
183 0 : LogPrint(BCLog::TOR, "tor: Successfully connected!\n");
184 0 : self->connected(*self);
185 0 : } else if (what & (BEV_EVENT_EOF|BEV_EVENT_ERROR)) {
186 0 : if (what & BEV_EVENT_ERROR) {
187 0 : LogPrint(BCLog::TOR, "tor: Error connecting to Tor control socket\n");
188 : } else {
189 0 : LogPrint(BCLog::TOR, "tor: End of stream\n");
190 : }
191 0 : self->Disconnect();
192 0 : self->disconnected(*self);
193 0 : }
194 0 : }
195 :
196 0 : bool TorControlConnection::Connect(const std::string &target, const ConnectionCB& _connected, const ConnectionCB& _disconnected)
197 : {
198 0 : if (b_conn)
199 0 : Disconnect();
200 : // Parse target address:port
201 0 : struct sockaddr_storage connect_to_addr;
202 0 : int connect_to_addrlen = sizeof(connect_to_addr);
203 0 : if (evutil_parse_sockaddr_port(target.c_str(),
204 0 : (struct sockaddr*)&connect_to_addr, &connect_to_addrlen)<0) {
205 0 : LogPrintf("tor: Error parsing socket address %s\n", target);
206 0 : return false;
207 : }
208 :
209 : // Create a new socket, set up callbacks and enable notification bits
210 0 : b_conn = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE);
211 0 : if (!b_conn)
212 0 : return false;
213 0 : bufferevent_setcb(b_conn, TorControlConnection::readcb, nullptr, TorControlConnection::eventcb, this);
214 0 : bufferevent_enable(b_conn, EV_READ|EV_WRITE);
215 0 : this->connected = _connected;
216 0 : this->disconnected = _disconnected;
217 :
218 : // Finally, connect to target
219 0 : if (bufferevent_socket_connect(b_conn, (struct sockaddr*)&connect_to_addr, connect_to_addrlen) < 0) {
220 0 : LogPrintf("tor: Error connecting to address %s\n", target);
221 0 : return false;
222 : }
223 0 : return true;
224 0 : }
225 :
226 0 : void TorControlConnection::Disconnect()
227 : {
228 0 : if (b_conn)
229 0 : bufferevent_free(b_conn);
230 0 : b_conn = nullptr;
231 0 : }
232 :
233 0 : bool TorControlConnection::Command(const std::string &cmd, const ReplyHandlerCB& reply_handler)
234 : {
235 0 : if (!b_conn)
236 0 : return false;
237 0 : struct evbuffer *buf = bufferevent_get_output(b_conn);
238 0 : if (!buf)
239 0 : return false;
240 0 : evbuffer_add(buf, cmd.data(), cmd.size());
241 0 : evbuffer_add(buf, "\r\n", 2);
242 0 : reply_handlers.push_back(reply_handler);
243 0 : return true;
244 0 : }
245 :
246 : /****** General parsing utilities ********/
247 :
248 : /* Split reply line in the form 'AUTH METHODS=...' into a type
249 : * 'AUTH' and arguments 'METHODS=...'.
250 : * Grammar is implicitly defined in https://spec.torproject.org/control-spec by
251 : * the server reply formats for PROTOCOLINFO (S3.21) and AUTHCHALLENGE (S3.24).
252 : */
253 10 : std::pair<std::string,std::string> SplitTorReplyLine(const std::string &s)
254 : {
255 : size_t ptr=0;
256 10 : std::string type;
257 82 : while (ptr < s.size() && s[ptr] != ' ') {
258 72 : type.push_back(s[ptr]);
259 72 : ++ptr;
260 : }
261 10 : if (ptr < s.size())
262 9 : ++ptr; // skip ' '
263 10 : return make_pair(type, s.substr(ptr));
264 10 : }
265 :
266 : /** Parse reply arguments in the form 'METHODS=COOKIE,SAFECOOKIE COOKIEFILE=".../control_auth_cookie"'.
267 : * Returns a map of keys to values, or an empty map if there was an error.
268 : * Grammar is implicitly defined in https://spec.torproject.org/control-spec by
269 : * the server reply formats for PROTOCOLINFO (S3.21), AUTHCHALLENGE (S3.24),
270 : * and ADD_ONION (S3.27). See also sections 2.1 and 2.3.
271 : */
272 27 : std::map<std::string,std::string> ParseTorReplyMapping(const std::string &s)
273 : {
274 27 : std::map<std::string,std::string> mapping;
275 58 : size_t ptr=0;
276 58 : while (ptr < s.size()) {
277 38 : std::string key, value;
278 246 : while (ptr < s.size() && s[ptr] != '=' && s[ptr] != ' ') {
279 208 : key.push_back(s[ptr]);
280 208 : ++ptr;
281 : }
282 38 : if (ptr == s.size()) // unexpected end of line
283 1 : return std::map<std::string,std::string>();
284 37 : if (s[ptr] == ' ') // The remaining string is an OptArguments
285 5 : break;
286 32 : ++ptr; // skip '='
287 32 : if (ptr < s.size() && s[ptr] == '"') { // Quoted string
288 18 : ++ptr; // skip opening '"'
289 : bool escape_next = false;
290 224 : while (ptr < s.size() && (escape_next || s[ptr] != '"')) {
291 : // Repeated backslashes must be interpreted as pairs
292 206 : escape_next = (s[ptr] == '\\' && !escape_next);
293 206 : value.push_back(s[ptr]);
294 206 : ++ptr;
295 : }
296 18 : if (ptr == s.size()) // unexpected end of line
297 1 : return std::map<std::string,std::string>();
298 17 : ++ptr; // skip closing '"'
299 : /**
300 : * Unescape value. Per https://spec.torproject.org/control-spec section 2.1.1:
301 : *
302 : * For future-proofing, controller implementors MAY use the following
303 : * rules to be compatible with buggy Tor implementations and with
304 : * future ones that implement the spec as intended:
305 : *
306 : * Read \n \t \r and \0 ... \377 as C escapes.
307 : * Treat a backslash followed by any other character as that character.
308 : */
309 17 : std::string escaped_value;
310 183 : for (size_t i = 0; i < value.size(); ++i) {
311 166 : if (value[i] == '\\') {
312 : // This will always be valid, because if the QuotedString
313 : // ended in an odd number of backslashes, then the parser
314 : // would already have returned above, due to a missing
315 : // terminating double-quote.
316 23 : ++i;
317 23 : if (value[i] == 'n') {
318 1 : escaped_value.push_back('\n');
319 22 : } else if (value[i] == 't') {
320 1 : escaped_value.push_back('\t');
321 21 : } else if (value[i] == 'r') {
322 1 : escaped_value.push_back('\r');
323 20 : } else if ('0' <= value[i] && value[i] <= '7') {
324 : size_t j;
325 : // Octal escape sequences have a limit of three octal digits,
326 : // but terminate at the first character that is not a valid
327 : // octal digit if encountered sooner.
328 21 : for (j = 1; j < 3 && (i+j) < value.size() && '0' <= value[i+j] && value[i+j] <= '7'; ++j) {}
329 : // Tor restricts first digit to 0-3 for three-digit octals.
330 : // A leading digit of 4-7 would therefore be interpreted as
331 : // a two-digit octal.
332 11 : if (j == 3 && value[i] > '3') {
333 1 : j--;
334 1 : }
335 11 : escaped_value.push_back(strtol(value.substr(i, j).c_str(), nullptr, 8));
336 : // Account for automatic incrementing at loop end
337 11 : i += j - 1;
338 11 : } else {
339 9 : escaped_value.push_back(value[i]);
340 : }
341 : } else {
342 143 : escaped_value.push_back(value[i]);
343 : }
344 : }
345 17 : value = escaped_value;
346 17 : } else { // Unquoted value. Note that values can contain '=' at will, just no spaces
347 132 : while (ptr < s.size() && s[ptr] != ' ') {
348 118 : value.push_back(s[ptr]);
349 118 : ++ptr;
350 : }
351 : }
352 31 : if (ptr < s.size() && s[ptr] == ' ')
353 11 : ++ptr; // skip ' ' after key=value
354 31 : mapping[key] = value;
355 38 : }
356 25 : return mapping;
357 27 : }
358 :
359 : /** Read full contents of a file and return them in a std::string.
360 : * Returns a pair <status, string>.
361 : * If an error occurred, status will be false, otherwise status will be true and the data will be returned in string.
362 : *
363 : * @param maxsize Puts a maximum size limit on the file that is read. If the file is larger than this, truncated data
364 : * (with len > maxsize) will be returned.
365 : */
366 0 : static std::pair<bool,std::string> ReadBinaryFile(const fs::path &filename, size_t maxsize=std::numeric_limits<size_t>::max())
367 : {
368 0 : FILE *f = fsbridge::fopen(filename, "rb");
369 0 : if (f == nullptr)
370 0 : return std::make_pair(false,"");
371 0 : std::string retval;
372 0 : char buffer[128];
373 : size_t n;
374 0 : while ((n=fread(buffer, 1, sizeof(buffer), f)) > 0) {
375 : // Check for reading errors so we don't return any data if we couldn't
376 : // read the entire file (or up to maxsize)
377 0 : if (ferror(f)) {
378 0 : fclose(f);
379 0 : return std::make_pair(false,"");
380 : }
381 0 : retval.append(buffer, buffer+n);
382 0 : if (retval.size() > maxsize)
383 : break;
384 : }
385 0 : fclose(f);
386 0 : return std::make_pair(true,retval);
387 0 : }
388 :
389 : /** Write contents of std::string to a file.
390 : * @return true on success.
391 : */
392 0 : static bool WriteBinaryFile(const fs::path &filename, const std::string &data)
393 : {
394 0 : FILE *f = fsbridge::fopen(filename, "wb");
395 0 : if (f == nullptr)
396 0 : return false;
397 0 : if (fwrite(data.data(), 1, data.size(), f) != data.size()) {
398 : fclose(f);
399 0 : return false;
400 : }
401 : fclose(f);
402 0 : return true;
403 0 : }
404 :
405 : /****** Bitcoin specific TorController implementation ********/
406 :
407 : /** Controller that connects to Tor control socket, authenticate, then create
408 : * and maintain an ephemeral onion service.
409 : */
410 : class TorController
411 : {
412 : public:
413 : TorController(struct event_base* base, const std::string& target);
414 : ~TorController();
415 :
416 : /** Get name of file to store private key in */
417 : fs::path GetPrivateKeyFile();
418 :
419 : /** Reconnect, after getting disconnected */
420 : void Reconnect();
421 : private:
422 : struct event_base* base;
423 : std::string target;
424 : TorControlConnection conn;
425 : std::string private_key;
426 : std::string service_id;
427 : bool reconnect;
428 : struct event *reconnect_ev;
429 : float reconnect_timeout;
430 : CService service;
431 : /** Cookie for SAFECOOKIE auth */
432 : std::vector<uint8_t> cookie;
433 : /** ClientNonce for SAFECOOKIE auth */
434 : std::vector<uint8_t> clientNonce;
435 :
436 : /** Callback for ADD_ONION result */
437 : void add_onion_cb(TorControlConnection& conn, const TorControlReply& reply);
438 : /** Callback for AUTHENTICATE result */
439 : void auth_cb(TorControlConnection& conn, const TorControlReply& reply);
440 : /** Callback for AUTHCHALLENGE result */
441 : void authchallenge_cb(TorControlConnection& conn, const TorControlReply& reply);
442 : /** Callback for PROTOCOLINFO result */
443 : void protocolinfo_cb(TorControlConnection& conn, const TorControlReply& reply);
444 : /** Callback after successful connection */
445 : void connected_cb(TorControlConnection& conn);
446 : /** Callback after connection lost or failed connection attempt */
447 : void disconnected_cb(TorControlConnection& conn);
448 :
449 : /** Callback for reconnect timer */
450 : static void reconnect_cb(evutil_socket_t fd, short what, void *arg);
451 : };
452 :
453 0 : TorController::TorController(struct event_base* _base, const std::string& _target):
454 0 : base(_base),
455 0 : target(_target), conn(base), reconnect(true), reconnect_ev(0),
456 0 : reconnect_timeout(RECONNECT_TIMEOUT_START)
457 0 : {
458 0 : reconnect_ev = event_new(base, -1, 0, reconnect_cb, this);
459 0 : if (!reconnect_ev)
460 0 : LogPrintf("tor: Failed to create event for reconnection: out of memory?\n");
461 : // Start connection attempts immediately
462 0 : if (!conn.Connect(_target, std::bind(&TorController::connected_cb, this, std::placeholders::_1),
463 0 : std::bind(&TorController::disconnected_cb, this, std::placeholders::_1) )) {
464 0 : LogPrintf("tor: Initiating connection to Tor control port %s failed\n", _target);
465 : }
466 : // Read service private key if cached
467 0 : std::pair<bool,std::string> pkf = ReadBinaryFile(GetPrivateKeyFile());
468 0 : if (pkf.first) {
469 0 : LogPrint(BCLog::TOR, "tor: Reading cached private key from %s\n", GetPrivateKeyFile().string());
470 0 : private_key = pkf.second;
471 : }
472 0 : }
473 :
474 0 : TorController::~TorController()
475 0 : {
476 0 : if (reconnect_ev) {
477 0 : event_free(reconnect_ev);
478 0 : reconnect_ev = nullptr;
479 0 : }
480 0 : if (service.IsValid()) {
481 0 : RemoveLocal(service);
482 : }
483 0 : }
484 :
485 0 : void TorController::add_onion_cb(TorControlConnection& _conn, const TorControlReply& reply)
486 : {
487 0 : if (reply.code == 250) {
488 0 : LogPrint(BCLog::TOR, "tor: ADD_ONION successful\n");
489 0 : for (const std::string &s : reply.lines) {
490 0 : std::map<std::string,std::string> m = ParseTorReplyMapping(s);
491 0 : std::map<std::string,std::string>::iterator i;
492 0 : if ((i = m.find("ServiceID")) != m.end())
493 0 : service_id = i->second;
494 0 : if ((i = m.find("PrivateKey")) != m.end())
495 0 : private_key = i->second;
496 0 : }
497 0 : if (service_id.empty()) {
498 0 : LogPrintf("tor: Error parsing ADD_ONION parameters:\n");
499 0 : for (const std::string &s : reply.lines) {
500 0 : LogPrintf(" %s\n", SanitizeString(s));
501 : }
502 0 : return;
503 : }
504 0 : service = LookupNumeric(std::string(service_id+".onion"), Params().GetDefaultPort());
505 0 : LogPrintf("tor: Got service ID %s, advertising service %s\n", service_id, service.ToString());
506 0 : if (WriteBinaryFile(GetPrivateKeyFile(), private_key)) {
507 0 : LogPrint(BCLog::TOR, "tor: Cached service private key to %s\n", GetPrivateKeyFile().string());
508 : } else {
509 0 : LogPrintf("tor: Error writing service private key to %s\n", GetPrivateKeyFile().string());
510 : }
511 0 : AddLocal(service, LOCAL_MANUAL);
512 : // ... onion requested - keep connection open
513 0 : } else if (reply.code == 510) { // 510 Unrecognized command
514 0 : LogPrintf("tor: Add onion failed with unrecognized command (You probably need to upgrade Tor)\n");
515 0 : } else {
516 0 : LogPrintf("tor: Add onion failed; error code %d\n", reply.code);
517 : }
518 0 : }
519 :
520 0 : void TorController::auth_cb(TorControlConnection& _conn, const TorControlReply& reply)
521 : {
522 0 : if (reply.code == 250) {
523 0 : LogPrint(BCLog::TOR, "tor: Authentication successful\n");
524 :
525 : // Now that we know Tor is running setup the proxy for onion addresses
526 : // if -onion isn't set to something else.
527 0 : if (gArgs.GetArg("-onion", "") == "") {
528 0 : CService resolved(LookupNumeric("127.0.0.1", 9050));
529 0 : proxyType addrOnion = proxyType(resolved, true);
530 0 : SetProxy(NET_ONION, addrOnion);
531 0 : SetReachable(NET_ONION, true);
532 0 : }
533 :
534 : // Finally - now create the service
535 0 : if (private_key.empty()) // No private key, generate one
536 0 : private_key = "NEW:RSA1024"; // Explicitly request RSA1024 - see issue #9214
537 : // Request onion service, redirect port.
538 : // Note that the 'virtual' port is always the default port to avoid decloaking nodes using other ports.
539 0 : _conn.Command(strprintf("ADD_ONION %s Port=%i,127.0.0.1:%i", private_key, Params().GetDefaultPort(), GetListenPort()),
540 0 : std::bind(&TorController::add_onion_cb, this, std::placeholders::_1, std::placeholders::_2));
541 0 : } else {
542 0 : LogPrintf("tor: Authentication failed\n");
543 : }
544 0 : }
545 :
546 : /** Compute Tor SAFECOOKIE response.
547 : *
548 : * ServerHash is computed as:
549 : * HMAC-SHA256("Tor safe cookie authentication server-to-controller hash",
550 : * CookieString | ClientNonce | ServerNonce)
551 : * (with the HMAC key as its first argument)
552 : *
553 : * After a controller sends a successful AUTHCHALLENGE command, the
554 : * next command sent on the connection must be an AUTHENTICATE command,
555 : * and the only authentication string which that AUTHENTICATE command
556 : * will accept is:
557 : *
558 : * HMAC-SHA256("Tor safe cookie authentication controller-to-server hash",
559 : * CookieString | ClientNonce | ServerNonce)
560 : *
561 : */
562 0 : 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)
563 : {
564 0 : CHMAC_SHA256 computeHash((const uint8_t*)key.data(), key.size());
565 0 : std::vector<uint8_t> computedHash(CHMAC_SHA256::OUTPUT_SIZE, 0);
566 0 : computeHash.Write(cookie.data(), cookie.size());
567 0 : computeHash.Write(clientNonce.data(), clientNonce.size());
568 0 : computeHash.Write(serverNonce.data(), serverNonce.size());
569 0 : computeHash.Finalize(computedHash.data());
570 : return computedHash;
571 0 : }
572 :
573 0 : void TorController::authchallenge_cb(TorControlConnection& _conn, const TorControlReply& reply)
574 : {
575 0 : if (reply.code == 250) {
576 0 : LogPrint(BCLog::TOR, "tor: SAFECOOKIE authentication challenge successful\n");
577 0 : std::pair<std::string,std::string> l = SplitTorReplyLine(reply.lines[0]);
578 0 : if (l.first == "AUTHCHALLENGE") {
579 0 : std::map<std::string,std::string> m = ParseTorReplyMapping(l.second);
580 0 : if (m.empty()) {
581 0 : LogPrintf("tor: Error parsing AUTHCHALLENGE parameters: %s\n", SanitizeString(l.second));
582 0 : return;
583 : }
584 0 : std::vector<uint8_t> serverHash = ParseHex(m["SERVERHASH"]);
585 0 : std::vector<uint8_t> serverNonce = ParseHex(m["SERVERNONCE"]);
586 0 : LogPrint(BCLog::TOR, "tor: AUTHCHALLENGE ServerHash %s ServerNonce %s\n", HexStr(serverHash), HexStr(serverNonce));
587 0 : if (serverNonce.size() != 32) {
588 0 : LogPrintf("tor: ServerNonce is not 32 bytes, as required by spec\n");
589 0 : return;
590 : }
591 :
592 0 : std::vector<uint8_t> computedServerHash = ComputeResponse(TOR_SAFE_SERVERKEY, cookie, clientNonce, serverNonce);
593 0 : if (computedServerHash != serverHash) {
594 0 : LogPrintf("tor: ServerHash %s does not match expected ServerHash %s\n", HexStr(serverHash), HexStr(computedServerHash));
595 0 : return;
596 : }
597 :
598 0 : std::vector<uint8_t> computedClientHash = ComputeResponse(TOR_SAFE_CLIENTKEY, cookie, clientNonce, serverNonce);
599 0 : _conn.Command("AUTHENTICATE " + HexStr(computedClientHash), std::bind(&TorController::auth_cb, this, std::placeholders::_1, std::placeholders::_2));
600 0 : } else {
601 0 : LogPrintf("tor: Invalid reply to AUTHCHALLENGE\n");
602 : }
603 0 : } else {
604 0 : LogPrintf("tor: SAFECOOKIE authentication challenge failed\n");
605 : }
606 0 : }
607 :
608 0 : void TorController::protocolinfo_cb(TorControlConnection& _conn, const TorControlReply& reply)
609 : {
610 0 : if (reply.code == 250) {
611 0 : std::set<std::string> methods;
612 0 : std::string cookiefile;
613 : /*
614 : * 250-AUTH METHODS=COOKIE,SAFECOOKIE COOKIEFILE="/home/x/.tor/control_auth_cookie"
615 : * 250-AUTH METHODS=NULL
616 : * 250-AUTH METHODS=HASHEDPASSWORD
617 : */
618 0 : for (const std::string &s : reply.lines) {
619 0 : std::pair<std::string,std::string> l = SplitTorReplyLine(s);
620 0 : if (l.first == "AUTH") {
621 0 : std::map<std::string,std::string> m = ParseTorReplyMapping(l.second);
622 0 : std::map<std::string,std::string>::iterator i;
623 0 : if ((i = m.find("METHODS")) != m.end())
624 0 : boost::split(methods, i->second, boost::is_any_of(","));
625 0 : if ((i = m.find("COOKIEFILE")) != m.end())
626 0 : cookiefile = i->second;
627 0 : } else if (l.first == "VERSION") {
628 0 : std::map<std::string,std::string> m = ParseTorReplyMapping(l.second);
629 0 : std::map<std::string,std::string>::iterator i;
630 0 : if ((i = m.find("Tor")) != m.end()) {
631 0 : LogPrint(BCLog::TOR, "tor: Connected to Tor version %s\n", i->second);
632 : }
633 0 : }
634 0 : }
635 0 : for (const std::string &s : methods) {
636 0 : LogPrint(BCLog::TOR, "tor: Supported authentication method: %s\n", s);
637 : }
638 : // Prefer NULL, otherwise SAFECOOKIE. If a password is provided, use HASHEDPASSWORD
639 : /* Authentication:
640 : * cookie: hex-encoded ~/.tor/control_auth_cookie
641 : * password: "password"
642 : */
643 0 : std::string torpassword = gArgs.GetArg("-torpassword", "");
644 0 : if (!torpassword.empty()) {
645 0 : if (methods.count("HASHEDPASSWORD")) {
646 0 : LogPrint(BCLog::TOR, "tor: Using HASHEDPASSWORD authentication\n");
647 0 : boost::replace_all(torpassword, "\"", "\\\"");
648 0 : _conn.Command("AUTHENTICATE \"" + torpassword + "\"", std::bind(&TorController::auth_cb, this, std::placeholders::_1, std::placeholders::_2));
649 0 : } else {
650 0 : LogPrintf("tor: Password provided with -torpassword, but HASHEDPASSWORD authentication is not available\n");
651 : }
652 0 : } else if (methods.count("NULL")) {
653 0 : LogPrint(BCLog::TOR, "tor: Using NULL authentication\n");
654 0 : _conn.Command("AUTHENTICATE", std::bind(&TorController::auth_cb, this, std::placeholders::_1, std::placeholders::_2));
655 0 : } else if (methods.count("SAFECOOKIE")) {
656 : // Cookie: hexdump -e '32/1 "%02x""\n"' ~/.tor/control_auth_cookie
657 0 : LogPrint(BCLog::TOR, "tor: Using SAFECOOKIE authentication, reading cookie authentication from %s\n", cookiefile);
658 0 : std::pair<bool,std::string> status_cookie = ReadBinaryFile(cookiefile, TOR_COOKIE_SIZE);
659 0 : if (status_cookie.first && status_cookie.second.size() == TOR_COOKIE_SIZE) {
660 : // _conn.Command("AUTHENTICATE " + HexStr(status_cookie.second), std::bind(&TorController::auth_cb, this, std::placeholders::_1, std::placeholders::_2));
661 0 : cookie = std::vector<uint8_t>(status_cookie.second.begin(), status_cookie.second.end());
662 0 : clientNonce = std::vector<uint8_t>(TOR_NONCE_SIZE, 0);
663 0 : GetRandBytes(clientNonce.data(), TOR_NONCE_SIZE);
664 0 : _conn.Command("AUTHCHALLENGE SAFECOOKIE " + HexStr(clientNonce), std::bind(&TorController::authchallenge_cb, this, std::placeholders::_1, std::placeholders::_2));
665 0 : } else {
666 0 : if (status_cookie.first) {
667 0 : LogPrintf("tor: Authentication cookie %s is not exactly %i bytes, as is required by the spec\n", cookiefile, TOR_COOKIE_SIZE);
668 : } else {
669 0 : LogPrintf("tor: Authentication cookie %s could not be opened (check permissions)\n", cookiefile);
670 : }
671 : }
672 0 : } else if (methods.count("HASHEDPASSWORD")) {
673 0 : LogPrintf("tor: The only supported authentication mechanism left is password, but no password provided with -torpassword\n");
674 : } else {
675 0 : LogPrintf("tor: No supported authentication method\n");
676 : }
677 0 : } else {
678 0 : LogPrintf("tor: Requesting protocol info failed\n");
679 : }
680 0 : }
681 :
682 0 : void TorController::connected_cb(TorControlConnection& _conn)
683 : {
684 0 : reconnect_timeout = RECONNECT_TIMEOUT_START;
685 : // First send a PROTOCOLINFO command to figure out what authentication is expected
686 0 : if (!_conn.Command("PROTOCOLINFO 1", std::bind(&TorController::protocolinfo_cb, this, std::placeholders::_1, std::placeholders::_2)))
687 0 : LogPrintf("tor: Error sending initial protocolinfo command\n");
688 0 : }
689 :
690 0 : void TorController::disconnected_cb(TorControlConnection& _conn)
691 : {
692 : // Stop advertising service when disconnected
693 0 : if (service.IsValid())
694 0 : RemoveLocal(service);
695 0 : service = CService();
696 0 : if (!reconnect)
697 : return;
698 :
699 0 : LogPrint(BCLog::TOR, "tor: Not connected to Tor control port %s, trying to reconnect\n", target);
700 :
701 : // Single-shot timer for reconnect. Use exponential backoff.
702 0 : struct timeval time = MillisToTimeval(int64_t(reconnect_timeout * 1000.0));
703 0 : if (reconnect_ev)
704 0 : event_add(reconnect_ev, &time);
705 0 : reconnect_timeout *= RECONNECT_TIMEOUT_EXP;
706 0 : }
707 :
708 0 : void TorController::Reconnect()
709 : {
710 : /* Try to reconnect and reestablish if we get booted - for example, Tor
711 : * may be restarting.
712 : */
713 0 : if (!conn.Connect(target, std::bind(&TorController::connected_cb, this, std::placeholders::_1),
714 0 : std::bind(&TorController::disconnected_cb, this, std::placeholders::_1) )) {
715 0 : LogPrintf("tor: Re-initiating connection to Tor control port %s failed\n", target);
716 0 : }
717 0 : }
718 :
719 0 : fs::path TorController::GetPrivateKeyFile()
720 : {
721 0 : return GetDataDir() / "onion_private_key";
722 0 : }
723 :
724 0 : void TorController::reconnect_cb(evutil_socket_t fd, short what, void *arg)
725 : {
726 0 : TorController *self = static_cast<TorController*>(arg);
727 0 : self->Reconnect();
728 0 : }
729 :
730 : /****** Thread ********/
731 : static struct event_base *gBase;
732 640 : static std::thread torControlThread;
733 :
734 0 : static void TorControlThread()
735 : {
736 0 : TorController ctrl(gBase, gArgs.GetArg("-torcontrol", DEFAULT_TOR_CONTROL));
737 :
738 0 : event_base_dispatch(gBase);
739 0 : }
740 :
741 0 : void StartTorControl()
742 : {
743 0 : assert(!gBase);
744 : #ifdef WIN32
745 : evthread_use_windows_threads();
746 : #else
747 0 : evthread_use_pthreads();
748 : #endif
749 0 : gBase = event_base_new();
750 0 : if (!gBase) {
751 0 : LogPrintf("tor: Unable to create event_base\n");
752 0 : return;
753 : }
754 :
755 0 : torControlThread = std::thread(std::bind(&TraceThread<void (*)()>, "torcontrol", &TorControlThread));
756 0 : }
757 :
758 529 : void InterruptTorControl()
759 : {
760 529 : if (gBase) {
761 0 : LogPrintf("tor: Thread interrupt\n");
762 0 : event_base_once(gBase, -1, EV_TIMEOUT, [](evutil_socket_t, short, void*) {
763 0 : event_base_loopbreak(gBase);
764 0 : }, nullptr, nullptr);
765 0 : }
766 529 : }
767 :
768 529 : void StopTorControl()
769 : {
770 529 : if (gBase) {
771 0 : torControlThread.join();
772 0 : event_base_free(gBase);
773 0 : gBase = nullptr;
774 0 : }
775 529 : }
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