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authorWladimir J. van der Laan <laanwj@gmail.com>2015-08-25 20:12:08 +0200
committerWladimir J. van der Laan <laanwj@gmail.com>2015-11-10 17:29:56 +0100
commit8f4e67f152a9625a1c66c20de00679286b2c187c (patch)
tree69a6b3f08d8dc830139ed169858be5f75dd20206 /src/torcontrol.cpp
parentb56953e9bb5a32bc35365d1f0c5de5528c0650dd (diff)
net: Automatically create hidden service, listen on Tor
Starting with Tor version 0.2.7.1 it is possible, through Tor's control socket API, to create and destroy 'ephemeral' hidden services programmatically. https://stem.torproject.org/api/control.html#stem.control.Controller.create_ephemeral_hidden_service This means that if Tor is running (and proper authorization is available), bitcoin automatically creates a hidden service to listen on, without user manual configuration. This will positively affect the number of available .onion nodes. - When the node is started, connect to Tor through control socket - Send `ADD_ONION` command - First time: - Make it create a hidden service key - Save the key in the data directory for later usage - Make it redirect port 8333 to the local port 8333 (or whatever port we're listening on). - Keep control socket connection open for as long node is running. The hidden service will (by default) automatically go away when the connection is closed.
Diffstat (limited to 'src/torcontrol.cpp')
-rw-r--r--src/torcontrol.cpp573
1 files changed, 573 insertions, 0 deletions
diff --git a/src/torcontrol.cpp b/src/torcontrol.cpp
new file mode 100644
index 0000000000..bb72315c8e
--- /dev/null
+++ b/src/torcontrol.cpp
@@ -0,0 +1,573 @@
+#include "torcontrol.h"
+#include "utilstrencodings.h"
+#include "net.h"
+#include "util.h"
+#include "init.h" // Just for ShutdownRequested
+
+#include <vector>
+#include <deque>
+#include <set>
+#include <stdlib.h>
+
+#include <boost/function.hpp>
+#include <boost/bind.hpp>
+#include <boost/signals2/signal.hpp>
+#include <boost/foreach.hpp>
+#include <boost/algorithm/string/predicate.hpp>
+#include <boost/algorithm/string/split.hpp>
+#include <boost/algorithm/string/classification.hpp>
+
+#include <event2/bufferevent.h>
+#include <event2/buffer.h>
+#include <event2/util.h>
+#include <event2/event.h>
+
+const std::string DEFAULT_TOR_CONTROL = "127.0.0.1:9051";
+
+/****** Low-level TorControlConnection ********/
+
+/** 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 boost::function<void(TorControlConnection&)> ConnectionCB;
+ typedef boost::function<void(TorControlConnection &,const TorControlReply &)> ReplyHandlerCB;
+
+ /** Create a new TorControlConnection.
+ */
+ TorControlConnection(struct event_base *base);
+ ~TorControlConnection();
+
+ /**
+ * Connect to a Tor control port.
+ * target is address of the form host:port.
+ * connected is the handler that is called when connection is succesfully established.
+ * disconnected is a handler that is called when the connection is broken.
+ * Return true on success.
+ */
+ bool Connect(const std::string &target, const ConnectionCB& connected, const ConnectionCB& disconnected);
+
+ /**
+ * Disconnect from Tor control port.
+ */
+ bool 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);
+
+ /** Response handlers for async replies */
+ boost::signals2::signal<void(TorControlConnection &,const TorControlReply &)> async_handler;
+private:
+ /** Callback when ready for use */
+ boost::function<void(TorControlConnection&)> connected;
+ /** Callback when connection lost */
+ boost::function<void(TorControlConnection&)> disconnected;
+ /** Libevent event base */
+ struct event_base *base;
+ /** Connection to control socket */
+ struct bufferevent *b_conn;
+ /** Message being received */
+ TorControlReply message;
+ /** Response handlers */
+ std::deque<ReplyHandlerCB> reply_handlers;
+
+ /** Libevent handlers: internal */
+ static void readcb(struct bufferevent *bev, void *ctx);
+ static void eventcb(struct bufferevent *bev, short what, void *ctx);
+};
+
+TorControlConnection::TorControlConnection(struct event_base *base):
+ base(base), b_conn(0)
+{
+}
+
+TorControlConnection::~TorControlConnection()
+{
+ if (b_conn)
+ bufferevent_free(b_conn);
+}
+
+void TorControlConnection::readcb(struct bufferevent *bev, void *ctx)
+{
+ TorControlConnection *self = (TorControlConnection*)ctx;
+ struct evbuffer *input = bufferevent_get_input(bev);
+ size_t n_read_out = 0;
+ char *line;
+ assert(input);
+ // If there is not a whole line to read, evbuffer_readln returns NULL
+ while((line = evbuffer_readln(input, &n_read_out, EVBUFFER_EOL_CRLF)) != NULL)
+ {
+ std::string s(line, n_read_out);
+ free(line);
+ if (s.size() < 4) // Short line
+ continue;
+ // <status>(-|+| )<data><CRLF>
+ self->message.code = atoi(s.substr(0,3).c_str());
+ self->message.lines.push_back(s.substr(4));
+ char ch = s[3]; // '-','+' or ' '
+ if (ch == ' ') {
+ // Final line, dispatch reply and clean up
+ if (self->message.code >= 600) {
+ // Dispatch async notifications to async handler
+ // Synchronous and asynchronous messages are never interleaved
+ self->async_handler(*self, self->message);
+ } else {
+ if (!self->reply_handlers.empty()) {
+ // Invoke reply handler with message
+ self->reply_handlers.front()(*self, self->message);
+ self->reply_handlers.pop_front();
+ } else {
+ LogPrintf("[tor] Received unexpected sync reply %i\n", self->message.code);
+ }
+ }
+ self->message.Clear();
+ }
+ }
+}
+
+void TorControlConnection::eventcb(struct bufferevent *bev, short what, void *ctx)
+{
+ TorControlConnection *self = (TorControlConnection*)ctx;
+ if (what & BEV_EVENT_CONNECTED) {
+ LogPrintf("[tor] Succesfully connected!\n");
+ self->connected(*self);
+ } else if (what & (BEV_EVENT_EOF|BEV_EVENT_ERROR)) {
+ if (what & BEV_EVENT_ERROR)
+ LogPrintf("[tor] Error connecting to Tor control socket\n");
+ else
+ LogPrintf("[tor] End of stream\n");
+ self->Disconnect();
+ self->disconnected(*self);
+ }
+}
+
+bool TorControlConnection::Connect(const std::string &target, const ConnectionCB& connected, const ConnectionCB& disconnected)
+{
+ if (b_conn)
+ Disconnect();
+ // Parse target address:port
+ struct sockaddr_storage connect_to_addr;
+ int connect_to_addrlen = sizeof(connect_to_addr);
+ if (evutil_parse_sockaddr_port(target.c_str(),
+ (struct sockaddr*)&connect_to_addr, &connect_to_addrlen)<0) {
+ perror("evutil_parse_sockaddr_port\n");
+ return false;
+ }
+
+ // Create a new socket, set up callbacks and enable notification bits
+ b_conn = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE);
+ if (!b_conn)
+ return false;
+ bufferevent_setcb(b_conn, TorControlConnection::readcb, NULL, TorControlConnection::eventcb, this);
+ bufferevent_enable(b_conn, EV_READ|EV_WRITE);
+ this->connected = connected;
+ this->disconnected = disconnected;
+
+ // Finally, connect to target
+ if (bufferevent_socket_connect(b_conn, (struct sockaddr*)&connect_to_addr, connect_to_addrlen) < 0) {
+ perror("bufferevent_socket_connect");
+ return false;
+ }
+ return true;
+}
+
+bool TorControlConnection::Disconnect()
+{
+ if (b_conn)
+ bufferevent_free(b_conn);
+ b_conn = 0;
+ return true;
+}
+
+bool TorControlConnection::Command(const std::string &cmd, const ReplyHandlerCB& reply_handler)
+{
+ if (!b_conn)
+ return false;
+ struct evbuffer *buf = bufferevent_get_output(b_conn);
+ if (!buf)
+ return false;
+ evbuffer_add(buf, cmd.data(), cmd.size());
+ evbuffer_add(buf, "\r\n", 2);
+ reply_handlers.push_back(reply_handler);
+ return true;
+}
+
+/****** General parsing utilities ********/
+
+/* Split reply line in the form 'AUTH METHODS=...' into a type
+ * 'AUTH' and arguments 'METHODS=...'.
+ */
+static std::pair<std::string,std::string> SplitTorReplyLine(const std::string &s)
+{
+ size_t ptr=0;
+ std::string type;
+ while (ptr < s.size() && s[ptr] != ' ') {
+ type.push_back(s[ptr]);
+ ++ptr;
+ }
+ if (ptr < s.size())
+ ++ptr; // skip ' '
+ return make_pair(type, s.substr(ptr));
+}
+
+/** Parse reply arguments in the form 'METHODS=COOKIE,SAFECOOKIE COOKIEFILE=".../control_auth_cookie"'.
+ */
+static std::map<std::string,std::string> ParseTorReplyMapping(const std::string &s)
+{
+ std::map<std::string,std::string> mapping;
+ size_t ptr=0;
+ while (ptr < s.size()) {
+ std::string key, value;
+ while (ptr < s.size() && s[ptr] != '=') {
+ key.push_back(s[ptr]);
+ ++ptr;
+ }
+ if (ptr == s.size()) // unexpected end of line
+ return std::map<std::string,std::string>();
+ ++ptr; // skip '='
+ if (ptr < s.size() && s[ptr] == '"') { // Quoted string
+ ++ptr; // skip '='
+ bool escape_next = false;
+ while (ptr < s.size() && (!escape_next && s[ptr] != '"')) {
+ escape_next = (s[ptr] == '\\');
+ value.push_back(s[ptr]);
+ ++ptr;
+ }
+ if (ptr == s.size()) // unexpected end of line
+ return std::map<std::string,std::string>();
+ ++ptr; // skip closing '"'
+ /* TODO: unescape value - according to the spec this depends on the
+ * context, some strings use C-LogPrintf style escape codes, some
+ * don't. So may be better handled at the call site.
+ */
+ } else { // Unquoted value. Note that values can contain '=' at will, just no spaces
+ while (ptr < s.size() && s[ptr] != ' ') {
+ value.push_back(s[ptr]);
+ ++ptr;
+ }
+ }
+ if (ptr < s.size() && s[ptr] == ' ')
+ ++ptr; // skip ' ' after key=value
+ mapping[key] = value;
+ }
+ return mapping;
+}
+
+/** Read full contents of a file and return them in a std::string. */
+static std::pair<bool,std::string> ReadBinaryFile(const std::string &filename)
+{
+ FILE *f = fopen(filename.c_str(), "rb");
+ if (f == NULL)
+ return std::make_pair(false,"");
+ std::string retval;
+ char buffer[128];
+ size_t n;
+ while ((n=fread(buffer, 1, sizeof(buffer), f)) > 0)
+ retval.append(buffer, buffer+n);
+ fclose(f);
+ return std::make_pair(true,retval);
+}
+
+/** Write contents of std::string to a file.
+ * @return true on success.
+ */
+static bool WriteBinaryFile(const std::string &filename, const std::string &data)
+{
+ FILE *f = fopen(filename.c_str(), "wb");
+ if (f == NULL)
+ return false;
+ if (fwrite(data.data(), 1, data.size(), f) != data.size())
+ return false;
+ fclose(f);
+ return true;
+}
+
+/****** Bitcoin specific TorController implementation ********/
+
+/** Controller that connects to Tor control socket, authenticate, then create
+ * and maintain a ephemeral hidden service.
+ */
+class TorController
+{
+public:
+ TorController(struct event_base* base, const std::string& target);
+ ~TorController();
+
+ /** Get name fo file to store private key in */
+ std::string GetPrivateKeyFile();
+
+ /** Reconnect, after getting disconnected */
+ void Reconnect();
+private:
+ struct event_base* base;
+ std::string target;
+ TorControlConnection conn;
+ std::string private_key;
+ std::string service_id;
+ bool reconnect;
+ struct event *shutdown_poll_ev;
+ struct event *reconnect_ev;
+ float reconnect_timeout;
+
+ /** Callback for ADD_ONION result */
+ void add_onion_cb(TorControlConnection& conn, const TorControlReply& reply);
+ /** Callback for AUTHENTICATE result */
+ void auth_cb(TorControlConnection& conn, const TorControlReply& reply);
+ /** Callback for PROTOCOLINFO result */
+ void protocolinfo_cb(TorControlConnection& conn, const TorControlReply& reply);
+ /** Callback after succesful connection */
+ void connected_cb(TorControlConnection& conn);
+ /** Callback after connection lost or failed connection attempt */
+ void disconnected_cb(TorControlConnection& conn);
+
+ /** Callback for shutdown poll timer */
+ static void shutdown_poll_cb(evutil_socket_t fd, short what, void *arg);
+ /** Callback for reconnect timer */
+ static void reconnect_cb(evutil_socket_t fd, short what, void *arg);
+};
+
+/** Exponential backoff configuration - initial timeout in seconds */
+static const float RECONNECT_TIMEOUT_START = 1.0;
+/** Exponential backoff configuration - growth factor */
+static const float RECONNECT_TIMEOUT_EXP = 1.5;
+
+TorController::TorController(struct event_base* base, const std::string& target):
+ base(base),
+ target(target), conn(base), reconnect(true), shutdown_poll_ev(0), reconnect_ev(0),
+ reconnect_timeout(RECONNECT_TIMEOUT_START)
+{
+ // Start connection attempts immediately
+ if (!conn.Connect(target, boost::bind(&TorController::connected_cb, this, _1),
+ boost::bind(&TorController::disconnected_cb, this, _1) )) {
+ LogPrintf("[tor] Initiating connection to Tor control port %s failed\n", target);
+ }
+ // Read service private key if cached
+ std::pair<bool,std::string> pkf = ReadBinaryFile(GetPrivateKeyFile());
+ if (pkf.first) {
+ LogPrintf("[tor] Reading cached private key from %s\n", GetPrivateKeyFile());
+ private_key = pkf.second;
+ }
+ // Periodic timer event to poll for shutdown
+ // The same 200ms as in bitcoind. This is not the nicest solution, but we cannot exactly use
+ // boost::interrupt here.
+ struct timeval time;
+ time.tv_usec = 200000;
+ time.tv_sec = 0;
+ shutdown_poll_ev = event_new(base, -1, EV_PERSIST, shutdown_poll_cb, this);
+ event_add(shutdown_poll_ev, &time);
+}
+
+TorController::~TorController()
+{
+ if (shutdown_poll_ev)
+ event_del(shutdown_poll_ev);
+ if (reconnect_ev)
+ event_del(reconnect_ev);
+}
+
+void TorController::add_onion_cb(TorControlConnection& conn, const TorControlReply& reply)
+{
+ if (reply.code == 250) {
+ LogPrintf("[tor] ADD_ONION succesful\n");
+ BOOST_FOREACH(const std::string &s, reply.lines) {
+ std::map<std::string,std::string> m = ParseTorReplyMapping(s);
+ std::map<std::string,std::string>::iterator i;
+ if ((i = m.find("ServiceID")) != m.end())
+ service_id = i->second;
+ if ((i = m.find("PrivateKey")) != m.end())
+ private_key = i->second;
+ }
+
+ CService service(service_id+".onion", GetListenPort(), false);
+ LogPrintf("[tor] Got service ID %s, advertizing service %s\n", service_id, service.ToString());
+ if (WriteBinaryFile(GetPrivateKeyFile(), private_key)) {
+ LogPrintf("[tor] Cached service private key to %s\n", GetPrivateKeyFile());
+ } else {
+ LogPrintf("[tor] Error writing service private key to %s\n", GetPrivateKeyFile());
+ }
+ AddLocal(service, LOCAL_MANUAL);
+ // ... onion requested - keep connection open
+ } else {
+ LogPrintf("[tor] Add onion failed\n");
+ }
+}
+
+void TorController::auth_cb(TorControlConnection& conn, const TorControlReply& reply)
+{
+ if (reply.code == 250) {
+ LogPrintf("[tor] Authentication succesful\n");
+ // Finally - now create the service
+ if (private_key.empty()) // No private key, generate one
+ private_key = "NEW:BEST";
+ // Request hidden service, redirect port.
+ // Note that the 'virtual' port doesn't have to be the same as our internal port, but this is just a convenient
+ // choice. TODO; refactor the shutdown sequence some day.
+ conn.Command(strprintf("ADD_ONION %s Port=%i,127.0.0.1:%i", private_key, GetListenPort(), GetListenPort()),
+ boost::bind(&TorController::add_onion_cb, this, _1, _2));
+ } else {
+ LogPrintf("[tor] Authentication failed\n");
+ }
+}
+
+void TorController::protocolinfo_cb(TorControlConnection& conn, const TorControlReply& reply)
+{
+ if (reply.code == 250) {
+ std::set<std::string> methods;
+ std::string cookiefile;
+ /*
+ * 250-AUTH METHODS=COOKIE,SAFECOOKIE COOKIEFILE="/home/x/.tor/control_auth_cookie"
+ * 250-AUTH METHODS=NULL
+ * 250-AUTH METHODS=HASHEDPASSWORD
+ */
+ BOOST_FOREACH(const std::string &s, reply.lines) {
+ std::pair<std::string,std::string> l = SplitTorReplyLine(s);
+ if (l.first == "AUTH") {
+ std::map<std::string,std::string> m = ParseTorReplyMapping(l.second);
+ std::map<std::string,std::string>::iterator i;
+ if ((i = m.find("METHODS")) != m.end())
+ boost::split(methods, i->second, boost::is_any_of(","));
+ if ((i = m.find("COOKIEFILE")) != m.end())
+ cookiefile = i->second;
+ } else if (l.first == "VERSION") {
+ std::map<std::string,std::string> m = ParseTorReplyMapping(l.second);
+ std::map<std::string,std::string>::iterator i;
+ if ((i = m.find("Tor")) != m.end()) {
+ LogPrintf("[tor] Connected to Tor version %s\n", i->second);
+ }
+ }
+ }
+ BOOST_FOREACH(const std::string &s, methods) {
+ LogPrintf("[tor] Supported authentication method: %s\n", s);
+ }
+ // Prefer NULL, otherwise COOKIE. If a password is provided, use HASHEDPASSWORD
+ // We do not support SAFECOOKIE
+ /* Authentication:
+ * cookie: hex-encoded ~/.tor/control_auth_cookie
+ * password: "password"
+ */
+ if (methods.count("NULL")) {
+ LogPrintf("[tor] Using NULL authentication\n");
+ conn.Command("AUTHENTICATE", boost::bind(&TorController::auth_cb, this, _1, _2));
+ } else if (methods.count("COOKIE")) {
+ // Cookie: hexdump -e '32/1 "%02x""\n"' ~/.tor/control_auth_cookie
+ LogPrintf("[tor] Using COOKIE authentication, reading cookie authentication from %s\n", cookiefile);
+ std::string cookie = ReadBinaryFile(cookiefile).second;
+ if (!cookie.empty()) {
+ conn.Command("AUTHENTICATE " + HexStr(cookie), boost::bind(&TorController::auth_cb, this, _1, _2));
+ } else {
+ LogPrintf("[tor] Authentication cookie not found\n");
+ }
+ } else {
+ /* TODO HASHEDPASSWORD w/ manual auth */
+ LogPrintf("[tor] No supported authentication method\n");
+ }
+ } else {
+ LogPrintf("[tor] Requesting protocol info failed\n");
+ }
+}
+
+void TorController::connected_cb(TorControlConnection& conn)
+{
+ reconnect_timeout = RECONNECT_TIMEOUT_START;
+ // First send a PROTOCOLINFO command to figure out what authentication is expected
+ if (!conn.Command("PROTOCOLINFO 1", boost::bind(&TorController::protocolinfo_cb, this, _1, _2)))
+ LogPrintf("[tor] Error sending initial protocolinfo command\n");
+}
+
+void TorController::disconnected_cb(TorControlConnection& conn)
+{
+ if (!reconnect)
+ return;
+ LogPrintf("[tor] Disconnected from Tor control port %s, trying to reconnect\n", target);
+ // Single-shot timer for reconnect. Use exponential backoff.
+ struct timeval time = MillisToTimeval(int64_t(reconnect_timeout * 1000.0));
+ reconnect_ev = event_new(base, -1, 0, reconnect_cb, this);
+ event_add(reconnect_ev, &time);
+ reconnect_timeout *= RECONNECT_TIMEOUT_EXP;
+}
+
+void TorController::Reconnect()
+{
+ /* Try to reconnect and reestablish if we get booted - for example, Tor
+ * may be restarting.
+ */
+ if (!conn.Connect(target, boost::bind(&TorController::connected_cb, this, _1),
+ boost::bind(&TorController::disconnected_cb, this, _1) )) {
+ LogPrintf("[tor] Re-initiating connection to Tor control port %s failed\n", target);
+ }
+}
+
+std::string TorController::GetPrivateKeyFile()
+{
+ return (GetDataDir() / "onion_private_key").string();
+}
+
+void TorController::shutdown_poll_cb(evutil_socket_t fd, short what, void *arg)
+{
+ TorController *self = (TorController*)arg;
+ if (ShutdownRequested()) {
+ // Shutdown was requested. Stop timers, and request control connection to terminate
+ LogPrintf("[tor] Thread interrupt\n");
+ if (self->shutdown_poll_ev)
+ event_del(self->shutdown_poll_ev);
+ self->shutdown_poll_ev = 0;
+ if (self->reconnect_ev)
+ event_del(self->reconnect_ev);
+ self->reconnect_ev = 0;
+ self->reconnect = false;
+ self->conn.Disconnect();
+ }
+}
+
+void TorController::reconnect_cb(evutil_socket_t fd, short what, void *arg)
+{
+ TorController *self = (TorController*)arg;
+ self->Reconnect();
+}
+
+/****** Thread ********/
+
+static void TorControlThread()
+{
+ struct event_base *base = event_base_new();
+ if (!base) {
+ LogPrintf("[tor] Unable to create event_base_new");
+ return;
+ }
+ TorController ctrl(base, GetArg("-torcontrol", DEFAULT_TOR_CONTROL));
+
+ event_base_dispatch(base);
+ event_base_free(base);
+}
+
+void StartTorControl(boost::thread_group& threadGroup, CScheduler& scheduler)
+{
+ threadGroup.create_thread(boost::bind(&TraceThread<void (*)()>, "torcontrol", &TorControlThread));
+}
+
+void StopTorControl()
+{
+ /* Nothing to do actually. Everything is cleaned up when thread exits */
+}
+